Paging FOAK; solar systems/immersion heater diverters/CT clamps

[Stephen Packer]

So... after waiting for around 7 months my solar system is finally installed.

15 panels giving 6kWp and a 5.6kWh battery.

It's been operating for a few days now (I had been using the battery for time
shifting my consumption to buy off peak and use on peak for a few weeks
though).

What I've found is at peak times with the sun shining the system is
delivering far more electricity than I can use and over the last few days it's always managed to charge the battery and run the house (even having a bit
left over on really sunny days to charge the car). But it's still exporting about a third of what's generated to the grid.

I've seen devices for sale that sense when you're exporting to the grid (through a CT clamp on the incoming cable) and then use the excess solar power to heat water through an immersion heater.

The existing system has a CT clamp on the incoming cable.

So... I assume that I can't do anything with the existing CT clamp to feed a 'solar diverter'.

I also presume that I could fit another CT clamp on the same piece of wire but probably with a reasonable distance from the original clamp to feed a solar diverter and allow it to make decisions about when to switch power on to the immersion heater. I think they're just a coil so I don't believe they are *that* likely to massively interfere with each other if they have some distance between them.

Anything I'm missing?

I'm relatively competent with home wiring and would place the diverter between the original feed to the hot water cylinder and the immersion element with the manual timer switched to 'on' all the time and the diverter 'doing the decision making' based on the input from the CT clamp.


Thanks in advance...

[RustyHinge]

I'll watch this thread with interest - I'm likely to install a similar
system soon.

--
Rusty Hinge
To err is human. To really foul things up requires a computer and the BOFH.

[siwilson]

On 12/10/2022 13:09, Stephen Packer wrote:

Dunno how he does it but my cousin dumps as much as he can into hot
water rather than back to the grid. I know he has the temp set very
high, and probably/hopefully[1] something to mix it automatically with cold.

[1] knowing his attitude to risk he may not have anything.

--
/Simon

[Paul Carmichael]

El Wed, 12 Oct 2022 15:57:02 +0100, siwilson escribió:

> Dunno how he does it but my cousin dumps as much as he can into hot
> water rather than back to the grid.

You see thaat 60a fuse...

I've been off grid for about 6 years now. A few weeks ago somebody came
and took the meter away. Well, I wasn't paying rental on it.

--
Paul.

https://paulc.es/elpatio

[Stephen Packer]

That's the 'solar diverter' gizmo I think.

On a dull day like today I've generated about 10kWh and this has resulted
in a charged battery, a dishwasher cycle, a loaf of bread and... 2.5kWh going to the
grid.

In the small hours the immersion timer will come on (off peak, 7.5p/kWh) and I'll
extract 2.5kWh from the grid to heat water. Much better if I could have just
dumped the excess power into my immersion heater today and not buy the electricity
in the small hours.

[Gyp]

On 12/10/2022 13:09, Stephen Packer wrote:

> Anything I'm missing?

I've got a Solar iBoost+ that clamps on and diverts the extra to the
immersion thingy which I suspect is what you are looking at.

I suspect the tech that's in use for your battery charger is basically
the same; monitor how much is leaving and adjust the charge to just
below the outgoing and track that until the battery is full.

Connecting the iBoost or similar with a second clamp would work in the
same way but there would be an ongoing variation in the amount of
electricity being directed to each throughout the charging period.

They are unlikely to "fight" each other but simply track as they would
with varying solar and consumption within the house.

The only downside that I can see is that, without additional switching,
there would be no way to prioritise where the electricity goes, so you
couldn't for example always fill up the hot water first.

I'm sure you're familiar with the way it works

[url=https://imgur.com/5BgIha0][img]http://i.imgur.com/5BgIha0.jpg[/img][/url]

iBoost tracks the solar from sunrise until the tank is up to temp
(10am-ish in this case), just keeps topping it up as necessary through
the day and then a big top up after the hot tap is run for a while.

In this example there would be loads to fill the battery up too

--
Gyp

[Stephen Packer]

On Wednesday, 12 October 2022 at 19:02:12 UTC+1, Gyp wrote:
> On 12/10/2022 13:09, Stephen Packer wrote:
> > Anything I'm missing?
>
> I've got a Solar iBoost+ that clamps on and diverts the extra to the
> immersion thingy which I suspect is what you are looking at.

It is, one of the products I considered also.

> I suspect the tech that's in use for your battery charger is basically
> the same; monitor how much is leaving and adjust the charge to just
> below the outgoing and track that until the battery is full.

Pretty much; with the exception that it's diverting some of the solar
panel DC straight to the battery rather than first putting it through the
inverter into 240v AC. It always seems to be exporting something
when there is sufficient sun; 14w or something silly like that.

> Connecting the iBoost or similar with a second clamp would work in the
> same way but there would be an ongoing variation in the amount of
> electricity being directed to each throughout the charging period.
>
> They are unlikely to "fight" each other but simply track as they would
> with varying solar and consumption within the house.
>
> The only downside that I can see is that, without additional switching,
> there would be no way to prioritise where the electricity goes, so you
> couldn't for example always fill up the hot water first.

I'm not sure I'd really worry too much about it. There are some devices
that have a timer on them so it needs a few seconds of sustained export
before it starts boiling water, maybe that would give 'battery priority'.

> I'm sure you're familiar with the way it works
>
> [url=https://imgur.com/5BgIha0][img]http://i.imgur.com/5BgIha0.jpg[/img][/url]
>
> iBoost tracks the solar from sunrise until the tank is up to temp
> (10am-ish in this case), just keeps topping it up as necessary through
> the day and then a big top up after the hot tap is run for a while.
>
> In this example there would be loads to fill the battery up too

Hmm. Link didn't work but rest of the post made sense. Thanks.

[marika]

Interesting stuff

Last week, after Florida experienced the very damaging hurricane and serious power loss, The news programs featured a community, which was powered by solar. They were right in the path, but were the only community that did not lose power

I was watching the report with my friend. It was quite cold there already. Drafty old farmhouse. Sitting before a propane fireplace , blankets and pet kittens on our knees, drinking hot beverages, anxiously anticipating the massive oil furnace heating bill

She was considering solar

She got sold on solar after that report
https://www.npr.org/2022/10/05/1126900340/florida-community-designed-weather-hurricane-ian-babcock-ranch-solar

[Boots]

On 13/10/2022 06:32 marika penned these words:

> anxiously anticipating the massive oil furnace heating bill

If I understood correctly[1] the use of both oil & propane for domestic heating
in the UK is verboten from 2026. Your friend may want to start looking into
alternatives now.

[1] Quite possible I have got the wrong end of the stick.
--
Ian

"Man will never be free until the last king is strangled with the entrails of
the last priest"

[marika]

On Wednesday, October 12, 2022 at 7:03:05 PM UTC-5, Boots wrote:
> On 13/10/2022 06:32 marika penned these words:
> > anxiously anticipating the massive oil furnace heating bill
> If I understood correctly[1] the use of both oil & propane for domestic heating
> in the UK is verboten from 2026. Your friend may want to start looking into
> alternatives now.
>
> [1] Quite possible I have got the wrong end of the stick.
> --

Lol
I was visiting northerly state of Maine USA, right near the Canada border.

I have no clue what the laws on that might be, but she bought it well over ten years ago, and if there is a law, older properties might be “grandfathered” to allow it

[Turby]

On 10/12/2022 5:09 AM, Stephen Packer wrote:
> So... after waiting for around 7 months my solar system is finally installed.
>
> 15 panels giving 6kWp and a 5.6kWh battery.
>

Here in San Diego it's illegal to go off grid, meaning I have to stay
connected to the independent SD Gas&Electric company, and they impose a
charge for that service. When I had solar cells installed ~7 years ago,
the installer asked what my yearly usage was, and put in 8 panels to
zero out my bill. (This year, I used 250kwh in Dec and -110kwh in Jul.)
My gas usage also peaks in Dec. I'd like to get a few more panels, but
seeing how my gas and electric usage peaks at the same time, it may be a
problem. I'd like to eliminate my gas usage totally. That means an
electric vehicle, cookers, and water heater. Batteries would be good,
but maybe not workable at those extremes. I dunno. You might have got me
going.


--
The erstwhile Thomas
FJR1300, R1200GS & ST1100 (in memoriam)

[ajh]

On 12/10/2022 13:09, Stephen Packer wrote:

> I've seen devices for sale that sense when you're exporting to the grid (through a CT clamp on the incoming cable) and then use the excess solar power to heat water through an immersion heater.

This guy, Gary does solar, doesn't reckon they pay back well:
https://youtu.be/1yAwgye-NVQ

I think the same, as the 400 quid cost would not be recouped here, I
walk upstairs and switch the immersion on when my battery is above 85%
SOC and as we do not draw hot water till evening it switches itself off
when up to temperature. I just have to remember to turn it off in the
evening but I'm working on a simple system to do that more automagically.

We are just entering the 5 month period when there will be no excess nor
will the solar provide enough for a full charge of the battery. I have
no off peak tariff to charge the battery at night.

I will be spending about £1.25/day on inefficiently heating the water by
gas with a 25 year old boiler.

I think things like the iboost and eddi are probably worthwhile in the
absence of a battery or an EV plugged in.

I assume the ct clamps actually measure phase relative to the grid but
am unsure.

[Paul Carmichael]

El Wed, 12 Oct 2022 15:32:49 -0700, marika escribió:

> Last week, after Florida experienced the very damaging hurricane and
> serious power loss, The news programs featured a community, which was
> powered by solar. They were right in the path, but were the only
> community that did not lose power

This was my main reason for going off-grid. I live in a 3rd world country
where all the cables are above ground and power cuts are frequent.

We also have a water tank with pump.

We hear people talking about the incessant power and water cuts and we
snigger.

--
Paul.

https://paulc.es/elpatio

[Paul Carmichael]

El Thu, 13 Oct 2022 10:17:19 +0100, ajh escribió:

> On 12/10/2022 13:09, Stephen Packer wrote:
>
>> I've seen devices for sale that sense when you're exporting to the grid
>> (through a CT clamp on the incoming cable) and then use the excess
>> solar power to heat water through an immersion heater.
>
>
> This guy, Gary does solar, doesn't reckon they pay back well:
> https://youtu.be/1yAwgye-NVQ
>
> I think the same, as the 400 quid cost would not be recouped here, I
> walk upstairs and switch the immersion on when my battery is above 85%
> SOC and as we do not draw hot water till evening it switches itself off
> when up to temperature. I just have to remember to turn it off in the
> evening but I'm working on a simple system to do that more
> automagically.

Our water heater is on a timer. It is only on during sunny hours. Works
fine for just 2 people.


--
Paul.

https://paulc.es/elpatio

[Paul Carmichael]

El Wed, 12 Oct 2022 15:19:43 +0000, Paul Carmichael escribió:

> El Wed, 12 Oct 2022 15:57:02 +0100, siwilson escribió:
>
>> Dunno how he does it but my cousin dumps as much as he can into hot
>> water rather than back to the grid.
>
> You see thaat 60a fuse...
>
> I've been off grid for about 6 years now. A few weeks ago somebody came
> and took the meter away. Well, I wasn't paying rental on it.

Just checked - Nov 2015. So almost 7 years at 150€ per month. It is now
half paid for. Trouble is I may soon have to fork out for new batteries -
unless Putin removes that need.


--
Paul.

https://paulc.es/elpatio

[ajh]

I suspect you have a bit better sunshine than SE England but in the last
220 days a timer on for a couple of hours each side of midday would
have worked for all but a hand full of days. Trouble is on those few
days there was not excess sunshine it would have whacked the battery so
we would have needed to buy electricity in the evening for cooking,
lighting etc.

As I said once you have a battery or EV you just need a simple logic
system rather than an expensive diverter that tries to match the excess
and divert it. This means you can use the battery to drive and buffer a
full power switched load rather than the diverter to modulate the load.

Okay this could potentially lessen the life of the battery but most of
the time the battery is hardly discharging.

[YTC#1]

On 13/10/2022 10:40, Paul Carmichael wrote:
> El Wed, 12 Oct 2022 15:32:49 -0700, marika escribió:
>
>> Last week, after Florida experienced the very damaging hurricane and
>> serious power loss, The news programs featured a community, which was
>> powered by solar. They were right in the path, but were the only
>> community that did not lose power
>
> This was my main reason for going off-grid. I live in a 3rd world country
> where all the cables are above ground and power cuts are frequent.

That's a harsh re-alignment of Spain. Based on where the cables are.
At least you have celectricty and ables, unlike some that are desinated
3rd world (which seems to be too losely used these days).

<checks the uk>
We have cables above ground as well.
</cuk>




--
Bruce Porter
"The internet is a huge and diverse community but mainly friendly"
http://ytc1.blogspot.co.uk/
There *is* an alternative! http://www.openoffice.org/

[RustyHinge]

On 13/10/2022 11:22, YTC#1 wrote:
>
>
> On 13/10/2022 10:40, Paul Carmichael wrote:
>> El Wed, 12 Oct 2022 15:32:49 -0700, marika escribió:
>>
>>> Last week, after Florida experienced the very damaging hurricane and
>>> serious power loss, The news programs featured a community,  which was
>>> powered by solar. They were right in the path, but were the only
>>> community that did not lose power
>>
>> This was my main reason for going off-grid. I live in a 3rd world country
>> where all the cables are above ground and power cuts are frequent.
>
> That's a harsh re-alignment of Spain. Based on where the cables are.
> At least you have celectricty and ables, unlike some that are desinated
> 3rd world (which seems to be too losely used these days).
>
> <checks the uk>
> We have cables above ground as well.
> </cuk>

Plenty - I'm supplied by noverhead cables and there are many azards to
that: main one is storms or gales blowing trees down on lines. Another
one is roadside runs being mown down by jamjars - the usual suspects
manage to hit a run nearby, and that means traffic is diverted down
unsuitable roads - noften past my house...

Another hazard is ploughs getting caught in the steel cable braces of poles.

[Paul Carmichael]

El Thu, 13 Oct 2022 11:22:07 +0100, YTC#1 escribió:

> On 13/10/2022 10:40, Paul Carmichael wrote:
>> El Wed, 12 Oct 2022 15:32:49 -0700, marika escribió:
>>
>>> Last week, after Florida experienced the very damaging hurricane and
>>> serious power loss, The news programs featured a community, which was
>>> powered by solar. They were right in the path, but were the only
>>> community that did not lose power
>>
>> This was my main reason for going off-grid. I live in a 3rd world
>> country where all the cables are above ground and power cuts are
>> frequent.
>
> That's a harsh re-alignment of Spain. Based on where the cables are. At
> least you have celectricty and ables, unlike some that are desinated 3rd
> world (which seems to be too losely used these days).

Anywhere with an underdeveloped infrastructure gets referred to as
"tercermundista" - so I'm guilty of mangling up cultures :-)

>
> <checks the uk>
> We have cables above ground as well.
> </cuk>

In the towns? We have 3 phase cabling everywhere (cables pretty thin).
For a new connection it's a case of "pick a phase, any phase". Max power
usually 5.6kW. We dream of 60 amp supply fuses. I think the max fuse to
protect the town cabling is 35a.


--
Paul.

https://paulc.es/elpatio

[Champ]

On Wed, 12 Oct 2022 05:09:47 -0700 (PDT), Stephen Packer
<stephen...@gmail.com> wrote:

>Anything I'm missing?

Dunno if you are, but I certainly am. Most of this is greek to me :-(
--
Champ
neal at champ dot org dot uk

I don't know, but I been told
You never slow down, you never grow old

[Andy Burns]

Boots wrote:

> If I understood correctly[1] the use of both oil & propane for domestic heating
> in the UK is verboten from 2026. Your friend may want to start looking into
> alternatives now.

The installation of new gas/oil systems is (supposedly) banned from that date,
existing systems are fine, personally I think they'll back-pedal anyway, just
like i think they'll back-pedal on petrol/diesel vehicles.

[Andy Burns]

ajh wrote:

> I think things like the iboost and eddi are probably worthwhile in the absence
> of a battery or an EV plugged in.
>
> I assume the ct clamps actually measure phase relative to the grid but am unsure.

If your inverter was out of phase with the grid, the magic smoke would have been
let out long ago ...

[ajh]

Could you explain it then? I thought to export the inverter has to
instantaneously have a higher voltage than the grid. As the grid is 50Hz
ac then at any moment in time the inverter has to lead the grid
fractionally for current to flow out.

[siwilson]

On 13/10/2022 11:22, YTC#1 wrote:
>
>

> On 13/10/2022 10:40, Paul Carmichael wrote:
>> El Wed, 12 Oct 2022 15:32:49 -0700, marika escribió:
>>
>>> Last week, after Florida experienced the very damaging hurricane and
>>> serious power loss, The news programs featured a community,  which was
>>> powered by solar. They were right in the path, but were the only
>>> community that did not lose power
>>
>> This was my main reason for going off-grid. I live in a 3rd world country
>> where all the cables are above ground and power cuts are frequent.
>
> That's a harsh re-alignment of Spain. Based on where the cables are.
> At least you have celectricty and ables, unlike some that are desinated
> 3rd world (which seems to be too losely used these days).
>
> <checks the uk>
> We have cables above ground as well.
> </cuk>
>

Yep, we had a 4 hour power cut this Monday due to trees.

--
/Simon

[Stephen Packer]

<snip>

Hmm. Thanks.

Bearing in mind I've only got a week's worth of operation experience I'm just
looking at how things are.

The water heating has been done at 3:00-4:30 AM when I've got the 7.5pp kWh
tariff, that's burning through (about) 2kWh a night, so that's 15p, or 55 quid a year.

However, a long shower or bath first thing and then the hot water is diluted with cold
and come the evening it's often luke warm.

I like the idea of switching the immersion on around mid-day for an hour or so to top
up since most days there has been an excess of solar power around this time resulting
in exporting since the battery is close to full. Even if it isn't full at this point there would
probably be (at the moment at least) sufficient time to top up the battery after the
immersion has switched off. However... I don't like the idea of this happening when there
isn't sufficient sun/battery since that'll result in using 'full price' electricity.

I've been 'sort of' doing this manually- plugging the car into charge when it's sunny and
the system has switched from charge to export, alternatively switching on the immersion
heater/washing machine/dishwasher/tumble drier; the battery really helps with this since
it adds the additional power needed at times the sun isn't quite bright enough/obscured by
a cloud etc. again avoiding using 'full price' electricity from the mains.

I suspect I'll end up getting a diverter for convenience^w laziness. Will watch and think for
a week or two more though.

[Andy Burns]

ajh wrote:

> Andy Burns wrote:
>
>> If your inverter was out of phase with the grid, the magic smoke would have
>> been let out long ago ...
>
> Could you explain it then? I thought to export the inverter has to
> instantaneously have a higher voltage than the grid. As the grid is 50Hz ac then
> at any moment in time the inverter has to lead the grid fractionally for current
> to flow out.

Yes the inverter does have to a slightly higher voltage than local mains to
actually "push" its output onto the grid, and in areas with large concentrations
of houses with solar, this can lead to them raising the local supply over the
magic 253 volts (230 + 10%) and therefore all the inverters shutdown.

But that just means they're higher voltage at all parts of the cycle, not that
they're out of phase with the grid, the inverter will be higher as the sine wave
is rising, and higher when it's falling, which is subtly different than saying
it's leading the phase of the grid ... more like leading on the rise and lagging
on the fall?

[ajh]

Thanks for the correction, clever stuff in these inverters.

[YTC#1]

On 13/10/2022 12:02, Paul Carmichael wrote:
> El Thu, 13 Oct 2022 11:22:07 +0100, YTC#1 escribió:
>
>> On 13/10/2022 10:40, Paul Carmichael wrote:
>>> El Wed, 12 Oct 2022 15:32:49 -0700, marika escribió:
>>>

>> That's a harsh re-alignment of Spain. Based on where the cables are. At
>> least you have celectricty and ables, unlike some that are desinated 3rd
>> world (which seems to be too losely used these days).
>
> Anywhere with an underdeveloped infrastructure gets referred to as
> "tercermundista" - so I'm guilty of mangling up cultures :-)

Typical Spanish, doing themselves down :-)

>
>>
>> <checks the uk>
>> We have cables above ground as well.
>> </cuk>
>
> In the towns? We have 3 phase cabling everywhere (cables pretty thin).
> For a new connection it's a case of "pick a phase, any phase". Max power
> usually 5.6kW. We dream of 60 amp supply fuses. I think the max fuse to
> protect the town cabling is 35a.
>
>

Sounds like Mexico City, and they don't have water 24 hours.
That must make them 4th world :-)

Maybe it is just Spanish/Latin speaking countries that have this issue.

[ajh]

On 13/10/2022 16:01, Stephen Packer wrote:
> I suspect I'll end up getting a diverter for convenience^w laziness. Will watch and think for
> a week or two more though.

Yes I agree but as you have an EV (I doubt I ever will) I would expect a
solar diverter car charger like the Zappi would be a better bet for
soaking up excess, unless electricity is your only means of heating water.


I think I will only spend £1.30/day in the 5 winter months on gas for
hot water plus £0.30/day 220 days of the year standing charge, when a
diverter simply wouldn't work, so £400 plus fitting doesn't look good
for me, although I'm all for leaving it all to just work, which it has
for a whole year.

[ajh]

On 13/10/2022 10:43, Paul Carmichael wrote:

> Our water heater is on a timer. It is only on during sunny hours. Works
> fine for just 2 people.

What I meant to ask you; my mate has just taken up residence[1] in his
grandparent's home near Vigo, which he has a share in because of the
inheritance regime in Spain. He says he cannot have solar PV because it
is taxed there, is this still so. When my late girlfriend moved 20 miles
north of Malaga in 2020 the solar profile looked absolutely ideal for
electricity for lighting, cooking plus heating and cooling with a split
aircon unit.

[1] to bring it on topic for the group I helped him out by riding his 25
year old CBR600 with 128k miles on the clock back round the M25 as he
left. It ran well but you do have to rev it to get it going, quite a
difference from my MT07.

I now wonder how long it will languish in my shed, MOT ran out last
month and I must top up the battery this month. At 58 I doubt he will be
back.

[Boots]

On 13/10/2022 20:14 Andy Burns penned these words:

Thanks I missed the new bit in the clip I was listening too or they glossed over
it since they were pushing heat pumps. I knew that new mains gas boilers are
supposed to be discontinued at some point 2030? I've just this year had a new
one in Liz's gaff whereas I no longer own a UK property so it is a moot point.

[Boots]

On 13/10/2022 17:45 Paul Carmichael penned these words:

The standing charge / meter rental or whatever you call it is madness.
Fortunately not something I have to suffer just pay for what you use and that's
banded the first 200Kwh are cheaper.

[Boots]

On 13/10/2022 20:30 Andy Burns penned these words:

I got caught out on that many moons ago. We had a bunch of kit installed in a BT
building they'd inadvertently put it onto the protected supply rather than
separate mains as a 3rd party. At one of their regular generator tests instead
of switching the generator in-phase the numptys managed to put it in anti phase
which cooked most of our rectifiers. I along with others was running around
London swiping from other sites so we could replace sufficient to keep the kit
up before the batteries keeled over.

[Paul Carmichael]

El Fri, 14 Oct 2022 08:57:35 +0800, Boots escribió:

> On 13/10/2022 17:45 Paul Carmichael penned these words:
>> El Wed, 12 Oct 2022 15:19:43 +0000, Paul Carmichael escribió:
>>
>>> El Wed, 12 Oct 2022 15:57:02 +0100, siwilson escribió:
>>>
>>>> Dunno how he does it but my cousin dumps as much as he can into hot
>>>> water rather than back to the grid.
>>>
>>> You see thaat 60a fuse...
>>>
>>> I've been off grid for about 6 years now. A few weeks ago somebody
>>> came and took the meter away. Well, I wasn't paying rental on it.
>>
>>
>> Just checked - Nov 2015. So almost 7 years at 150€ per month. It is now
>> half paid for. Trouble is I may soon have to fork out for new batteries
>> -
>> unless Putin removes that need.
>
> The standing charge / meter rental or whatever you call it is madness.
> Fortunately not something I have to suffer just pay for what you use and
> that's banded the first 200Kwh are cheaper.

In France and Spain we are charged a minimum based on the max wattage
contracted. As you say, madness.


--
Paul.

https://paulc.es/elpatio

[Paul Carmichael]

El Thu, 13 Oct 2022 22:15:59 +0100, ajh escribió:

> On 13/10/2022 10:43, Paul Carmichael wrote:
>> Our water heater is on a timer. It is only on during sunny hours. Works
>> fine for just 2 people.
>
> What I meant to ask you; my mate has just taken up residence[1] in his
> grandparent's home near Vigo, which he has a share in because of the
> inheritance regime in Spain. He says he cannot have solar PV because it
> is taxed there, is this still so.

That was imposed by a rogue minister and was scrapped. There is still
some paperwork (taxes?) if you generate over 15kW, but it would have to
be a pretty big house. We generate up to 6kW. The gov is even giving
grants now. Everyone that has any spare cash is chucking it at solar
panels.

The only issue is what type of installation to install. Mine is off grid
so I can do what I like. My holiday home, down the road, has just 12
panels to feed the pool pump/heater. No batteries. That has a certificate
stating that it doesn't inject into the grid, so as not to kill the
repair workers when they're a patching up the latest outage. If the mains
goes off, that system shuts down.

Tell him to speak to the leccy provider. They are all offering schemes.


--
Paul.

https://paulc.es/elpatio

[siwilson]

On 12/10/2022 13:09, Stephen Packer wrote:

> So... after waiting for around 7 months my solar system is finally installed.
>

<swerve>

My panels on the MoHo have been great during the summer.

But, today, my 2x300W panels are generating... 15W.

The trickle chargers for the other batteries, plus running a Raspberry
PI and 4g router consume 20W. So the main battery is still discharging.
It can probably run for a few more days like that but then I'll need to
plug it into something if the sun doesn't shine :(

--
/Simon

[Paul Carmichael]

El Fri, 14 Oct 2022 11:02:59 +0100, siwilson escribió:

> My panels on the MoHo have been great during the summer.
>
> But, today, my 2x300W panels are generating... 15W.
>
> The trickle chargers for the other batteries, plus running a Raspberry
> PI and 4g router consume 20W. So the main battery is still discharging.
> It can probably run for a few more days like that but then I'll need to
> plug it into something if the sun doesn't shine :(

I know we'd be a tad fucked without it, but we are really sick of the sun
this year. Bring on the rain.

Send me an empty sun box and I'll send it back full for you :-)

My MPPTs are currently strangling throughput as the batteries are almost
charged. Right now we're getting a measly 4kW.

The down side of lead/acid batteries is the need to top up every 40 days
(in the loft - really cramped).


--
Paul.

https://paulc.es/elpatio

[Mike Fleming]

Fear the trees!

Oh, wrong newsgroup. Never mind.

[Turby]

On 10/13/2022 2:40 AM, Paul Carmichael wrote:
> El Wed, 12 Oct 2022 15:32:49 -0700, marika escribió:
>

>> Last week, after Florida experienced the very damaging hurricane and
>> serious power loss, The news programs featured a community, which was
>> powered by solar. They were right in the path, but were the only
>> community that did not lose power
>
> This was my main reason for going off-grid. I live in a 3rd world country
> where all the cables are above ground and power cuts are frequent.
>

> We also have a water tank with pump.
>
> We hear people talking about the incessant power and water cuts and we
> snigger.
>
A significant cause of catastrophic wildfires in California is above
ground power lines being hit by falling trees. There is a movement to
bury the lines, but it's very expensive.

--
The erstwhile Thomas
FJR1300, R1200GS & ST1100 (in memoriam)

[jeremy]

On 12 Oct 2022 at 17:13:45 BST, "Stephen Packer" <stephen...@gmail.com>
wrote:

>
> On a dull day like today I've generated about 10kWh and this has resulted
> in a charged battery, a dishwasher cycle, a loaf of bread and... 2.5kWh going
> to the
> grid.

So this time of year - approximately 12 hours of daylight - 10kwh generated on
a dull day - how much do you consume in a day (24 hours) typically at this
time of year?

I may be missing something important here - like is there a commitment that
you have to send x% back to the grid (or is it only above an agreed
threshold)?


--
jeremy

[Stephen Packer]

Generally I'm consuming around 14-20kWh a day depending on how much
cooking gets done. On top of this there's probably another 20-30kWh to
charge the car during the week (obviously depends on usage).

On an even duller day (yesterday) the system only generated 7kWh.

Although on a bright day (last Saturday) it generated 29kWh.

I've no commitment to send anything to the grid, I paid outright for the
system. But anything I don't consume (or charge my battery with) will
go to the grid and once I've got the paperwork in place I'll be paid for this.

It's a little complicated with 'tariffs'[1] but I suspect I'll end up selling it for
around 4-5p a unit, this week's export would have been about 40 units, so
maybe 2 quid.


[1] I'm with Octopus 'Go' for car charging reasons (7.5p/kWh between
00:30 and 04:30) which limits what I can sell to Octopus for (just their
SEG tariff at 4.1p/kWh). I could sell to someone else though.
To be studied. and studied...

[YTC#1]

It's the old capex V opex isn't it.

Cheap to put up during that years budget.
Expensive over time as they are damaged/cause damage.

But if buried initially, high cost out of that budget.
Cheaper to maintain over time.

[YTC#1]

On 15/10/2022 11:31, Stephen Packer wrote:
> On Saturday, 15 October 2022 at 10:23:54 UTC+1, jeremy wrote:
>> On 12 Oct 2022 at 17:13:45 BST, "Stephen Packer" <stephen...@gmail.com>
>> wrote:
>>
>>>
>>> On a dull day like today I've generated about 10kWh and this has resulted
>>> in a charged battery, a dishwasher cycle, a loaf of bread and... 2.5kWh going
>>> to the
>>> grid.
>>
>> So this time of year - approximately 12 hours of daylight - 10kwh generated on
>> a dull day - how much do you consume in a day (24 hours) typically at this
>> time of year?
>>
>> I may be missing something important here - like is there a commitment that
>> you have to send x% back to the grid (or is it only above an agreed
>> threshold)?
>
> Generally I'm consuming around 14-20kWh a day depending on how much
> cooking gets done. On top of this there's probably another 20-30kWh to
> charge the car during the week (obviously depends on usage).

I'm new to the smart meter lark, but 1 month in I am using less than
7Kw/day.

Still awaiting a quote to see if I can have solar fitted.

[jeremy]

On 15 Oct 2022 at 11:31:54 BST, "Stephen Packer" <stephen...@gmail.com>

Thanks, good explanation. I assume the quantity of electricity generated is
directly proportional to the sq metres of panels you have (and I suppose the
quality of the panels) - in which case, roof surface area is your limiting
factor (or upfront cost) - like if you could double your generation then you
could approach (save for the car charging) near self-sufficiency from the
solar power.

With daily average of 20kwh if level across the year (which it won't be of
course but assuming it does) if my maths is right that's (@ 34p/kwh) around
£2,500 annual cost.

I hven't considered this before but looking at a few sites now - one
(https://www.greenmatch.co.uk/solar-energy/solar-system/6kw-solar-panel-syste
m#output) says this:

> "The performance of your 6 kW solar system depends on several things such as
> the direction your roof is facing, its angling and of course the quality of
> the materials used.
>
> With a south facing roof and the right angling, the system will generate
> approximately 4.5 kWh for each kW installed, minus some minor losses that are
> likely to occur. Such efficiency losses might appear from weather conditions
> or some slight shading over your panels."

I assume this 4.5kwh is over the course of a day - and therefore such a
solution could generate 6 x 4.5 = 27kwh per day - am I reading this right?

The same website suggests 9-11k install cost and £430 annual electricity bill
savings - I'm misunderstanding something here - if I drew an average of
20kwh/day then we know the cost of this is circa £2,500 - I guess the
difference here is that I may be generating it but not consuming it at the
time of generation and without a battery it just flows back to the grid (for a
lower price than what I pay for it) - is my understanding correct? If so it
sounds like having the battery within the solution is quite important.


--
jeremy

[RustyHinge]

Whereabouts are you? If appropriate I can send you the emu of an
approved fitter.
--
Rusty Hinge
To err is human. To really foul things up requires a computer and the BOFH.

[Stephen Packer]

On Saturday, 15 October 2022 at 18:08:15 UTC+1, jeremy wrote:
<snip>

> Thanks, good explanation. I assume the quantity of electricity generated is
> directly proportional to the sq metres of panels you have (and I suppose the
> quality of the panels) - in which case, roof surface area is your limiting
> factor (or upfront cost) - like if you could double your generation then you
> could approach (save for the car charging) near self-sufficiency from the
> solar power.
>

Yes, surface area is proportional to panels (and orientation/quality).

I've got them ground mounted rather than roof due to wind here (on
the top of a hill and the wind blows hard).

> With daily average of 20kwh if level across the year (which it won't be of
> course but assuming it does) if my maths is right that's (@ 34p/kwh) around
> £2,500 annual cost.

Somewhere around that, yes and dependent on tariff. Due to the electric car I'm
on Octopus Go and try to do all the 'juicy' things overnight, well at least I used to
pre-solar.

> I hven't considered this before but looking at a few sites now - one
> (https://www.greenmatch.co.uk/solar-energy/solar-system/6kw-solar-panel-syste
> m#output) says this:
>
> > "The performance of your 6 kW solar system depends on several things such as
> > the direction your roof is facing, its angling and of course the quality of
> > the materials used.
> >
> > With a south facing roof and the right angling, the system will generate
> > approximately 4.5 kWh for each kW installed, minus some minor losses that are
> > likely to occur. Such efficiency losses might appear from weather conditions
> > or some slight shading over your panels."
>
> I assume this 4.5kwh is over the course of a day - and therefore such a
> solution could generate 6 x 4.5 = 27kwh per day - am I reading this right?

That's how I read it and I assume that's an average over the year so some
months it'll be less (due to short days, low angle of sun, clouds) and others
it'll be more.

> The same website suggests 9-11k install cost and £430 annual electricity bill
> savings - I'm misunderstanding something here - if I drew an average of
> 20kwh/day then we know the cost of this is circa £2,500 - I guess the
> difference here is that I may be generating it but not consuming it at the
> time of generation and without a battery it just flows back to the grid (for a
> lower price than what I pay for it) - is my understanding correct? If so it
> sounds like having the battery within the solution is quite important.

Yes, if you don't consume it by burning it in the house; washing, cooking
water heating, car charging whatever it'll be sent to the grid where it will
net a small amount depending on who you sell it to (and there is a limit of
around 3.5kW of what can be pushed back without special approval so
the peak size of the solar array needs to take this into account; although the
inverter output can be 'throttled' to comply with the limit at 'peak
production' while having a larger array for a larger generation at less
favourable production times.

Batteries are expensive I calculated a small one (6kWh give or take) would
be worthwhile. To add just 6kWh would cost me 'about'
2.5-3k. This would enable me to avoid buying about 5kWh of power a
day and to instead offset this with not selling 5kWh of power (on a day
with plenty of sun; 32p-5p = 27p/unit = £1.35 a day saving) or on a dull day I'd
buy at 7.5 p rather than 32p ; saving £1.22 a day.
So assuming a quarter of the days were the 1.22 saving the blended
saving's something like £1.30 a day.

£2,500/£1.30 = 5 and a bit years pay back.

I am tempted to add the second battery... but want to watch the system work
for a bit before I commit.

It's expensive but it's the whole spend CAPEX to avoid OPEX thing that I
sort of remember from the days when I ran budgets with other people's
money!

[siwilson]

On 15/10/2022 19:10, Stephen Packer wrote:

>
> Batteries are expensive I calculated a small one (6kWh give or take) would
> be worthwhile. To add just 6kWh would cost me 'about'
> 2.5-3k.

Please show your working? A 5kWh pylontech - ~£1,500 (when they arrive,
that is)

--
/Simon

[Stephen Packer]

Solax triple power 5.8kWh 'slave' battery is around that price.

I'm stuck with that since the inverter and the 'master' battery is Solax.


I should have added in the previous calculation email that the reasons
I didn't go for the 11.6kWh option (or larger) were:

a) I was told to expect less power generated than I've seen so I didn't think
I'd necessarily be able to fully charge the batteries from the panels (to
date I think I would about 5/8 days this month). I guess as the days
shorten it'll be more likely I won't have the 'spare' solar to charge the
second battery; so maybe it's something like 1/3 of the year that I
won't be able to do this?

b) I'm not convinced it's safe to rely on very cheap off-peak electricity
like Octopus Go! to make the 'business case' for a second battery to
work.

So if I run the numbers assuming I make a £1.30 daily saving 2/3 of the
year that's around £320 quid giving payback of almost 8 years. If it's
half of the year then payback stretches out to about 10 years.

People expect Lithium batteries to have a life span of around ten years
and that their capacity will drop with age/use. The Nissan Leaf's battery
is pretty crude and seems to be doing better than expected[1], so maybe this
is pessimistic. But either way I need to get more 'generation experience'
before I decide if I drop the money on extra battery.


[1] Mine's a 2017 model with around 42k that's still giving full capacity and
the same mileage as when new.

[Turby]

On 10/15/2022 9:04 AM, YTC#1 wrote:
> On 15/10/2022 01:19, Turby wrote:
>> On 10/13/2022 2:40 AM, Paul Carmichael wrote:
>>> El Wed, 12 Oct 2022 15:32:49 -0700, marika escribió:
>>>
>>>> Last week, after Florida experienced the very damaging hurricane and
>>>> serious power loss, The news programs featured a community,  which was
>>>> powered by solar. They were right in the path, but were the only
>>>> community that did not lose power
>>>
>>> This was my main reason for going off-grid. I live in a 3rd world
>>> country
>>> where all the cables are above ground and power cuts are frequent.
>>>
>>> We also have a water tank with pump.
>>>
>>> We hear people talking about the incessant power and water cuts and we
>>> snigger.
>>>
>> A significant cause of catastrophic wildfires in California is above
>> ground power lines being hit by falling trees. There is a movement to
>> bury the lines, but it's very expensive.
>>
>
> It's the old capex V opex isn't it.
>
> Cheap to put up during that years budget.
> Expensive over time as they are damaged/cause damage.
>
> But if buried initially, high cost out of that budget.
> Cheaper to maintain over time.
>
>

Pacific Gas & Electric is California's largest but not only power
company. They have admitted culpability for some fires and will pay over
$55 million in one case. They have committed to undergrounding at least
10,000 miles of cables at a cost of over $3 million per mile.

[Turby]

On 10/13/2022 4:25 AM, Champ wrote:
> On Wed, 12 Oct 2022 05:09:47 -0700 (PDT), Stephen Packer
> <stephen...@gmail.com> wrote:
>
>> Anything I'm missing?
>
> Dunno if you are, but I certainly am. Most of this is greek to me :-(

Oh. I thought it was Farsi.

[YTC#1]

Yep, cheaper to pay out claims (via insurance).
With all that cheap labour over there, someone is making a mint.

[YTC#1]

Merseyside.
Getting one as part of this
<url:https://www.liverpoolcityregion-ca.gov.uk/what-we-do/energy-environment/solar-together/>

[Mark Olson]

YTC#1 <b...@ytc1-spambin.co.uk> wrote:
> I'm new to the smart meter lark, but 1 month in I am using less than
> 7Kw/day.

Here, have an 'h;. Your units as stated are power/time, not joules.

--
FJR1300A, GL1000, KLR650A6F, EX250J9A, DR200SE, Vespa Ciao

[Stephen Packer]

On Sunday, 16 October 2022 at 15:53:25 UTC+1, Mark Olson wrote:
> YTC#1 <b...@ytc1-spambin.co.uk> wrote:
> > I'm new to the smart meter lark, but 1 month in I am using less than
> > 7Kw/day.
> Here, have an 'h;. Your units as stated are power/time, not joules.

If you're going to be unkind you might as well mention it's kW, not Kw.

Easy mistake to make in the UK though since no one can get Kwasi Kwarteng
out of their minds, or pensions / mortgages etc.

[Paul Carmichael]

El Sun, 16 Oct 2022 08:35:38 -0700, Stephen Packer escribió:

> On Sunday, 16 October 2022 at 15:53:25 UTC+1, Mark Olson wrote:
>> YTC#1 <b...@ytc1-spambin.co.uk> wrote:
>> > I'm new to the smart meter lark, but 1 month in I am using less than
>> > 7Kw/day.
>> Here, have an 'h;. Your units as stated are power/time, not joules.
>
> If you're going to be unkind you might as well mention it's kW, not Kw.

And it's really not worth trying to explain to people that 1 kW = 1 kWh/h.

Yesterday I thought I'd missed learning about another use of the word
lechuga (lettuce) until I saw the picture.

Strange how different cultures have different funny-bones.

--
Paul.

https://paulc.es/elpatio

[Mark Olson]

Stephen Packer <stephen...@gmail.com> wrote:
> On Sunday, 16 October 2022 at 15:53:25 UTC+1, Mark Olson wrote:
>> YTC#1 <b...@ytc1-spambin.co.uk> wrote:
>> > I'm new to the smart meter lark, but 1 month in I am using less than
>> > 7Kw/day.
>> Here, have an 'h;. Your units as stated are power/time, not joules.
>
> If you're going to be unkind you might as well mention it's kW, not Kw.

I did notice the incorrect K and w but felt the lack of hours was
the most egregious fault.

> Easy mistake to make in the UK though since no one can get Kwasi Kwarteng
> out of their minds, or pensions / mortgages etc.

Check out Sally Cruickshank's video from 1975, "Quasi at the
Quackadero". I can't help thinking of it every time I hear the ex-CX's
name mentioned.

I really do feel for folks in the UK. Not only have your investments
suffered as ours have, from Putin's mad adventurism, but you've got
a double whammy from your own clown show masquerading as a government.

[Stephen Packer]

On Sunday, 16 October 2022 at 17:57:59 UTC+1, Mark Olson wrote:

> I really do feel for folks in the UK. Not only have your investments
> suffered as ours have, from Putin's mad adventurism, but you've got
> a double whammy from your own clown show masquerading as a government.

Sadly many of the population need to feel a significant amount of pain
to shake them out of their torpor. This shit is what the largest minority
voted for in 2019; a country laid low by little more than racism.

[RustyHinge]

Oh. The folk I'm in contact withoperate in East Anglia.

get in touch with us via the contact form
http://emailclick.ichoosr.com/ls/click?upn=jb1H6e690HPTNFWjt-2Bx-2FKma2-2F0OIEi8rL75nc0YCFFZoaItG2NeLh8X3PwV8D6Ag5tenVbJJZqGRBvR-2BLtKB6A-3D-3DwJkZ_Ni3H6W0bYIdvQJCdK3WbBOjsu-2FArJB2Lj16t2uZ22rQmmNCsiv8sfQcrrerH96wRa7GNquhakd-2BHIz8mdfjLsWddCtE8Y1Y87edxcfXFzDyqcuHlzoN8RucBgvg2CiCDJDJaghNt7jnpy4-2BAJqYPAzGfsON6vVsgztmGyLc-2FGk-2BeGCBe1P0EuAuEp-2BjfIj0zwoj7C33F7NfcnkoAT-2FiT3YdwrIqfcJqrJlhUu9OG0xxuU-2BGW18XWTYmy8Qv3g5fU28KqFIydjzm9TRhq5bDRSRfYtXh9-2FpZgAsjrBxutK-2FHBjECpYPDIltBJBvRModb8ydshqGJYBdm-2BkeEprFo1cm2IK67q1nA9yHlomL0gX4dFbUR8RlbDONqKHZp4h42EUAFpxHhGWr2F5Z-2BVeK6tetuWu8KInYDj-2F5Chj8vs147iDQ9TvYZyNLO3I1kOVbbtI-2FVDN9CCEn4Tai27V2r-2FlBlDTvMlLZy-2FbR5wxSQKQm3-2BvqzP449Wcfw8lrCUKzGzXtJ6r6Ad6rC-2F-2BZM2e1WGG2t2pjBnVyQCgGQSfAwI1oHGZUUbHtpUli77J7kDP5xKSfy3-2BlkhEFhZMA2KZKXCcM-2BCB3zXpKKAGxujk-2BGxrNFvcPhYbemPdKRA9mxlR3OVLxDm5l09amjYLkH7-2BsnwWyUgrtBIC4V0NfHsBzOlQ6cvgktmPtpobdY08iISgyIgZ44m1QAEo9DK9c7BesO737iuWRSzyvtR-2Fwtc-2FQz00IM-3D

These people may be able to point you at something useful.

[Turby]

On 10/16/2022 11:32 AM, RustyHinge wrote:
>
>
> get in touch with us via the contact form
> http://emailclick.ichoosr.com/ls/click?upn=jb1H6e690HPTNFWjt-2Bx-2FKma2-2F0OIEi8rL75nc0YCFFZoaItG2NeLh8X3PwV8D6Ag5tenVbJJZqGRBvR-2BLtKB6A-3D-3DwJkZ_Ni3H6W0bYIdvQJCdK3WbBOjsu-2FArJB2Lj16t2uZ22rQmmNCsiv8sfQcrrerH96wRa7GNquhakd-2BHIz8mdfjLsWddCtE8Y1Y87edxcfXFzDyqcuHlzoN8RucBgvg2CiCDJDJaghNt7jnpy4-2BAJqYPAzGfsON6vVsgztmGyLc-2FGk-2BeGCBe1P0EuAuEp-2BjfIj0zwoj7C33F7NfcnkoAT-2FiT3YdwrIqfcJqrJlhUu9OG0xxuU-2BGW18XWTYmy8Qv3g5fU28KqFIydjzm9TRhq5bDRSRfYtXh9-2FpZgAsjrBxutK-2FHBjECpYPDIltBJBvRModb8ydshqGJYBdm-2BkeEprFo1cm2IK67q1nA9yHlomL0gX4dFbUR8RlbDONqKHZp4h42EUAFpxHhGWr2F5Z-2BVeK6tetuWu8KInYDj-2F5Chj8vs147iDQ9TvYZyNLO3I1kOVbbtI-2FVDN9CCEn4Tai27V2r-2FlBlDTvMlLZy-2FbR5wxSQKQm3-2BvqzP449Wcfw8lrCUKzGzXtJ6r6Ad6rC-2F-2BZM2e1WGG2t2pjBnVyQCgGQSfAwI1oHGZUUbHtpUli77J7kDP5xKSfy3-2BlkhEFhZMA2KZKXCcM-2BCB3zXpKKAGxujk-2BGxrNFvcPhYbemPdKRA9mxlR3OVLxDm5l09amjYLkH7-2BsnwWyUgrtBIC4V0NfHsBzOlQ6cvgktmPtpobdY08iISgyIgZ44m1QAEo9DK9c7BesO737iuWRSzyvtR-2Fwtc-2FQz00IM-3D
>

Is that the world's longest link?

[YTC#1]

<snip>

Yes, it is a nationwide scheme, operated locally

>
> These people may be able to point you at something useful.
>


--

[YTC#1]

On 16/10/2022 23:07, Turby wrote:
> On 10/16/2022 11:32 AM, RustyHinge wrote:
>>
>>
>> get in touch with us via the contact form

<snip>

>
> Is that the world's longest link?
>
>

And it leads to .... https://solartogether.co.uk/south-norfolk/home
:-)

[YTC#1]

On 16/10/2022 15:53, Mark Olson wrote:
> YTC#1 <b...@ytc1-spambin.co.uk> wrote:
>> I'm new to the smart meter lark, but 1 month in I am using less than
>> 7Kw/day.
>
> Here, have an 'h;. Your units as stated are power/time, not joules.
>

Mb, MB. Gb,GiB....

Yeah, I'll get the drift eventually....

[Ace]

On 16 Oct 2022 16:10:45 GMT, Paul Carmichael <wibble...@gmail.com>
wrote:

>El Sun, 16 Oct 2022 08:35:38 -0700, Stephen Packer escribió:
>
>> On Sunday, 16 October 2022 at 15:53:25 UTC+1, Mark Olson wrote:
>>> YTC#1 <b...@ytc1-spambin.co.uk> wrote:
>>> > I'm new to the smart meter lark, but 1 month in I am using less than
>>> > 7Kw/day.
>>> Here, have an 'h;. Your units as stated are power/time, not joules.
>>
>> If you're going to be unkind you might as well mention it's kW, not Kw.
>
>And it's really not worth trying to explain to people that 1 kW = 1 kWh/h.

One kilowatt per hour? How does that work then?

--
Ace
http://www.chaletbeauroc.com/

[chrisnd @ukrm]

It doesn't - try re-reading Paul's comment a little more closely :-)
Chris

--
The Deuchars BBB#40 COFF#14
Yamaha XV750SE & Suzuki GS550t
http://www.Deuchars.org.uk

[ajh]

You need to factor in an inverter. A hybrid one is fine and cheap for
the solar panels but an AC coupled one is able to take charge off peak
from the grid. It also means when the sun is shining the power output of
the two inverters is added.

Personally if I were doing it all again I would go with 3 pylontech 3000
(10kWh now ~£5000 having leapt in price over the summer)batteries and
pay more to have the solar inverter a Victron one that can operate in
islanded mode. Avoid proprietary stuff that needs to "phone home" to
china constantly, although mine is faultless it hinders future expansion.

Panels are cheap so fit the maximum 6kW on a 3kW inverter will simply
limit them but in dull weather the extra is well worthwhile. The DNO
will be happy as long as the inverter self limits exports to 3.7kW and
reacts within 5 seconds to do so.

I am adding 1.5kW on a SE facing mount to compliment my current 4kW SW
facing array. This week I have started buying a few kWh from Eon for the
first time since March.

[Stephen Packer]

I'm still sucking my teeth about battery capacity (based on a week and a half's
operation). I'm guessing that in the summer because of the longer hours of
sunlight I'll have less need for large battery storage so the only time it will
really benefit me is times like now when the days are shortening but there
is still plenty of sun, or... when days are short and there is limited sun but the
ability to effectively 'time shift' consumption from on-peak use to off-peak
battery charging from the mains (but that relies on the tariffs still being around).

I think the 6kWh array is *probably* enough, I guess it's diminishing returns to add
more since most days it's more than fed the house while the sun is shining. I guess
a bigger array of panels helps when days are dull.

I think if buying again I'd also have chosen the option to have an output from my
battery/inverter when there's a power cut. I don't *think* my inverter/battery
controller supports this. Not really sure, suppose I could check.

[Ace]

On Mon, 17 Oct 2022 11:53:49 +0100, "chrisnd @ukrm"
<chr...@privacy.net> wrote:

>On 17/10/2022 11:07, Ace wrote:
>> On 16 Oct 2022 16:10:45 GMT, Paul Carmichael <wibble...@gmail.com>
>> wrote:
>>
>>> El Sun, 16 Oct 2022 08:35:38 -0700, Stephen Packer escribió:
>>>
>>>> On Sunday, 16 October 2022 at 15:53:25 UTC+1, Mark Olson wrote:
>>>>> YTC#1 <b...@ytc1-spambin.co.uk> wrote:
>>>>>> I'm new to the smart meter lark, but 1 month in I am using less than
>>>>>> 7Kw/day.
>>>>> Here, have an 'h;. Your units as stated are power/time, not joules.
>>>>
>>>> If you're going to be unkind you might as well mention it's kW, not Kw.
>>>
>>> And it's really not worth trying to explain to people that 1 kW = 1 kWh/h.
>>
>> One kilowatt per hour? How does that work then?
>
>It doesn't - try re-reading Paul's comment a little more closely :-)
>Chris

ooops, mea cupla.
--
Ace
http://www.chaletbeauroc.com/

[Sqirrel99]

RustyHinge wrote:
> I can send you the emu of an approved fitter.

That didn't do Rod Hull much good when he was messing about on his roof.

[ajh]

On 17/10/2022 12:15, Stephen Packer wrote:
>
>> first time since March.
>
> I'm still sucking my teeth about battery capacity (based on a week and a half's
> operation). I'm guessing that in the summer because of the longer hours of
> sunlight I'll have less need for large battery storage so the only time it will
> really benefit me is times like now when the days are shortening but there
> is still plenty of sun, or... when days are short and there is limited sun but the
> ability to effectively 'time shift' consumption from on-peak use to off-peak
> battery charging from the mains (but that relies on the tariffs still being around).
>
> I think the 6kWh array is *probably* enough, I guess it's diminishing returns to add
> more since most days it's more than fed the house while the sun is shining. I guess
> a bigger array of panels helps when days are dull.
>
> I think if buying again I'd also have chosen the option to have an output from my
> battery/inverter when there's a power cut. I don't *think* my inverter/battery
> controller supports this. Not really sure, suppose I could check.

Yes I agree with all you say there.

I think my 4kW array 10 years ago and the £3400 6.5kWh battery, 1 year
ago, were the optimum cost benefit for me, everything since has become
more expensive. I am adding some panels just to give an earlier bit of
generation and it may extend the "shoulder" month's generation to be
self sufficient by up to 20 days, which is probably only worth £30/year
for an investment of £1500. Whereas the battery has meant I have self
consumed nearly all the generation which is now worth about £1200, now
some of that will not have gone through the battery and a small amount
is still imported but even at £600 that will pay back before the battery
warranty expires and I expect a lot more although I am unlikely too see it.

Once you factor in an EV it looks much better and having a 10kWh battery
to buffer electricity while you are out driving seems a good thing.

There is not much benefit once past the equinox simply because unless
you charge the battery at a cheap off peak rate the battery will not
often reach capacity until the next equinox (March 5 to October 10 in my
case this summer.

I will not interfere with my current PV inverter while it works but will
replace it with a significantly more expensive Victron unit that will
run the whole PV system and house load during a daylight power cut or
until the battery is run down.

I do have a generator changeover switch, and TT earth arrangement, but
my tiny inverter generator does not have a clean enough sine
wave/voltage to keep the battery or solar inverters alive. It will run
house lights and TV etc. and the charge in the battery will still be
there when grid power comes back.

[RustyHinge]

Who he?

[Eddie]

On 17/10/2022 14:25, RustyHinge wrote:
> On 17/10/2022 13:12, Sqirrel99 wrote:
>> RustyHinge wrote:
>>> I can send you the emu of an approved fitter.
>>
>> That didn't do Rod Hull much good when he was messing about on his roof.
>
> Who he?

https://en.wikipedia.org/wiki/Rod_Hull#Death

--
Eddie ed...@deguello.org

[chrisnd @ukrm]

On 17/10/2022 14:25, RustyHinge wrote:

> On 17/10/2022 13:12, Sqirrel99 wrote:
>> RustyHinge wrote:
>>> I can send you the emu of an approved fitter.
>>
>> That didn't do Rod Hull much good when he was messing about on his roof.
>
> Who he?
>

Info here: https://en.wikipedia.org/wiki/Rod_Hull
Fall from roof here: https://www.theguardian.com/uk/1999/mar/18/2

I really don't know why I felt compelled to google that. I was never a
fan. Honest.

[Stephen Packer]

On Monday, 17 October 2022 at 14:20:32 UTC+1, ajh wrote:
<snip>

> I think my 4kW array 10 years ago and the £3400 6.5kWh battery, 1 year
> ago, were the optimum cost benefit for me, everything since has become
> more expensive. I am adding some panels just to give an earlier bit of
> generation and it may extend the "shoulder" month's generation to be
> self sufficient by up to 20 days, which is probably only worth £30/year
> for an investment of £1500. Whereas the battery has meant I have self
> consumed nearly all the generation which is now worth about £1200, now
> some of that will not have gone through the battery and a small amount
> is still imported but even at £600 that will pay back before the battery
> warranty expires and I expect a lot more although I am unlikely too see it.

<snip>

One other thing the battery allows is buffering of intermittent sun if something
very 'juicy' (e.g. car charging/immersion heater) is going on. So when the array's
generating >4kW it's happy enough with a 3.2kW or so load, but all it takes is a
cloud and the generation drops to 1-2kW and the shortfall is pulled from the mains.
With the battery, the shortfall comes from the battery until the cloud disappears
and then the excess over the house load gets dumped into the battery until it's
full again.

[ajh]

Yes so we agree on all

[Scraggy]

On Wed, 12 Oct 2022 05:09:47 -0700 (PDT), Stephen Packer
<stephen...@gmail.com> wrote:

>So... after waiting for around 7 months my solar system is finally installed.
>
>15 panels giving 6kWp and a 5.6kWh battery.
>
>It's been operating for a few days now (I had been using the battery for time
>shifting my consumption to buy off peak and use on peak for a few weeks
>though).
>
>What I've found is at peak times with the sun shining the system is
>delivering far more electricity than I can use and over the last few days it's always managed to charge the battery and run the house (even having a bit
>left over on really sunny days to charge the car). But it's still exporting about a third of what's generated to the grid.
>
>I've seen devices for sale that sense when you're exporting to the grid (through a CT clamp on the incoming cable) and then use the excess solar power to heat water through an immersion heater.
>
>The existing system has a CT clamp on the incoming cable.
>
>So... I assume that I can't do anything with the existing CT clamp to feed a 'solar diverter'.
>
>I also presume that I could fit another CT clamp on the same piece of wire but probably with a reasonable distance from the original clamp to feed a solar diverter and allow it to make decisions about when to switch power on to the immersion heater. I think they're just a coil so I don't believe they are *that* likely to massively interfere with each other if they have some distance between them.
>
>Anything I'm missing?
>
>I'm relatively competent with home wiring and would place the diverter between the original feed to the hot water cylinder and the immersion element with the manual timer switched to 'on' all the time and the diverter 'doing the decision making' based on the input from the CT clamp.
>
>
>Thanks in advance...


Just a comment , to which the assembled experts may give the answer.
I only have PV solar, so, if the power goes off, so does the
solar(inverters), theoretically. I have a changeover switch that
disconnectes me from the mains, so that when my generator comes online
inverters are restored and the generator runs the house aided by the
PV.
I'm assuming that, as you have battey power, it will supply the
inverter but does this have consequences outside your property if you
are poking power into a 'dead' line or is there some sort of cutout?

[ajh]

On 18/10/2022 14:24, Scraggy wrote:

>
> Just a comment , to which the assembled experts may give the answer.
> I only have PV solar, so, if the power goes off, so does the
> solar(inverters), theoretically. I have a changeover switch that
> disconnectes me from the mains, so that when my generator comes online
> inverters are restored and the generator runs the house aided by the
> PV.

If so your generator provides a better waveform AND?OR more stable
voltage regulation than mine, the inverters stay off line if I use my
generaotor, when the changeover is switched to it.

> I'm assuming that, as you have battey power, it will supply the
> inverter but does this have consequences outside your property if you
> are poking power into a 'dead' line or is there some sort of cutout?

It should cut out until it sees a grid connection again. Many have an
Emergency Power Supply that will run some maintained loads in a grid
outage but these should not feed the incoming mains unless there is a
cut off, also as I said before there may be earthing issues which cause
RCDs not to trip.

[chrisnd @ukrm]

For the record, modern (ie double pole) RCDs should not need an earth to
trip. Some older, single pole, versions may* have done.

As ajh has said though, do check the earthing out. It is a Good Thing to
have an earth**.

HTH, Chris
*keeping the options open there :-)
**or even *the* Earth!

[Stephen Packer]

On Tuesday, 18 October 2022 at 14:24:28 UTC+1, Scraggy wrote:

> Just a comment , to which the assembled experts may give the answer.
> I only have PV solar, so, if the power goes off, so does the
> solar(inverters), theoretically. I have a changeover switch that
> disconnectes me from the mains, so that when my generator comes online
> inverters are restored and the generator runs the house aided by the
> PV.
> I'm assuming that, as you have battey power, it will supply the
> inverter but does this have consequences outside your property if you
> are poking power into a 'dead' line or is there some sort of cutout?

In short, no. A version of the inverter/battery charger I have does this (it has an
emergency output which is a dedicated circuit, not the 'normal' output.) I'm not
sure if the version I have installed is this version. It certainly doesn't have the
emergency output connected if it is. One thing I didn't really think about when I
ordered it. .

[RustyHinge]

On 18/10/2022 14:24, Scraggy wrote:

There must be (by law) a solenoid or other means of detecting a power
outage and when the system is mains-fed.

This is held 'closed' by mains potential until the power goes off.

(Counter intuitively, 'closed' means that the switch is 'on'.)

No mains power causes the solenoid to open, isolating your system.

When the mains power goes on again, the solenoid/w.h.y? first breaks the
contact between your system and the mains, and then <Tommy Cooper> just
like that </TC> either gravity or a spring switching back to mains
connection, so there's no possibility of the two systems interfering
with one-another.

[Paul Carmichael]

El Mon, 17 Oct 2022 14:20:29 +0100, ajh escribió:

> I will not interfere with my current PV inverter while it works but will
> replace it with a significantly more expensive Victron unit

This.

--
Paul.

https://paulc.es/elpatio

[Stephen Packer]

On Wednesday, 12 October 2022 at 13:09:49 UTC+1, Stephen Packer wrote:
<snip>

I ended up following Gyp's lead and using an 'Solar iBoost' diverter.

It's got no 'communication' with the inverter so all it 'knows' is when power is
flowing from my home to the grid (through a sense clamp on the supply cable).

When the battery is charged then the inverter delivers what is available, with any
excess over the house demand being 'exported' to the grid. If the export passes a
trigger point (which can be set between 100 and 500W) then the 'diverter' switches
in and uses the export power to instead heat the water.

It's quite clever how it works in that it sets up the voltage delivered to the immersion
heater to provide the amount of excess power that was being delivered to the grid;
if the sun shines harder the power going to grid goes up and is then diverted to the
immersion heater by the voltage applied to its terminals being raised. It seems to
be sampling the diverted power about once a second or so (the display shows how
much power is being diverted at any given time).

I do wonder if it could end up in a position where the solar diverter is sucking power
from the battery rather than 'solar excess', maybe if the sun disappeared behind a
cloud and the power to the immersion heater was momentarily supplied by the mains
then the inverter would step in and supply the power from the battery? However I have
not yet seen this; I set the 'trigger point' to 500W but think I'll reduce it a bit.

Anyway... after a couple of days it seems to work fine. The CT clamps are as far apart
as I can get them and don't seem to be interfering with each other. I guess the only
further modification *could* be to add a solar aware car charger... but I think that's for
the summer.

Thanks for all the thoughts.

[Gyp]

<thumb up emoji>
--
Gyp

[siwilson]

On 18/11/2022 14:42, Stephen Packer wrote:

Not sure I follow this. Why wouldn't you want *all* solar to go to the
immersion until the water was hot, and only then start exporting?

I'd like to do something similar but the scale of my solar setup in the
motorhome is much smaller of course. (Some recent days I've generated
pretty much 0 power).

The main inverter draws about 30W just at idle, so I'm not currently
using that, but have plugged in a small (300W) inverter instead. That
draws 10W on idle so .24kWh/day. What I want is this inverter to only
switch on when the solar is generating enough excess during the day so
that it will charge the other batteries (starter+separate leisure). At
the moment I'm using a timer based on sunrise+1 and sunset-1. I can't
find any simple way to measure the incoming solar power. Similarly in
the summer I'd like to power the fridge providing the solar is
generating >300W. This is one of the reasons everyone goes with Victron
of course because all of this info is readily available and can be
published to eg MQTT to do all sorts of cleverness.

--
/Simon

[RustyHinge]

The immersion heater only uses a current which is below solar input?
Excess electrickery has to go somewhere if the battery is fully charged.

[Stephen Packer]

Here's how I think it works...

The hybrid inverter is connected to the consumer unit, the solar panels
and the battery. It's setup to prioritise 'self use', then charging the battery
then exporting to the grid. It senses current flow into/out of the house
via a CT clamp on the supply cable.

The 'diverter' is connected to the consumer unit and the immersion heater.
It senses when electricity is being exported by a CT clamp on the supply
cable. The only time current flows out of the house is when the inverter
is supplying more power than the house is consuming.

The inverter samples current flow using its CT clamp and generates
whatever power the house is currently consuming either from the
panels, or the battery or some combination (there are timers to only
allow battery use at certain times of the day, but lets ignore those...).
Generally on a clear day when the sun is shining there's more power
than I can use if there's nothing going on (cooking, laundry etc.).
At the moment the panels are delivering 1.2kW and that power is split
between the house (230W), the battery (974W) and some small
amount to the grid (8W). Note the battery is DC coupled so the inverter
is only delivering about 240W.

Once the battery is charged then the inverter will dump whatever
excess power there is to the grid (up to a limit set in its config).

When the battery is enabled for 'discharge' (by the timer) then when the
house is drawing more than the inverter can supply from the panels it
supplements by drawing on the battery, slowly discharging it.
Again, the battery use relies on the inverter understanding current flow
from the CT clamp on the supply cable, the inverter delivers a slightly
higher supply voltage than the mains to maintain a small flow of power
out of the house (tens of watts).

The diverter is also sensing the flow of current (with a different
clamp but on the same cable). If it sees more power than its threshold
setting (100-500W in 50W increments) flowing out of the house it then
powers the immersion stepping up the voltage to the immersion to match
the excess power (export-threshold) being exported, until the thermostat
on the immersion trips.

The 'diverter' has no knowledge of the source of the power; solar or battery,
it's just switching based on the amount of power flowing out of the house.

The inverter has no knowledge of the diverter operation, it's just trying to
avoid any power flowing into the house from the grid based on using the
solar panels and (if enabled) the battery power.

The risk is that:
- The inverter has charged the battery and is now exporting power,
- The diverter senses this and starts drawing an appropriate amount
of power (to match the export-threshold),
- The sun goes down/is covered by a cloud,
- The inverter replaces the power from the panels with power from the
battery, discharging the battery,
- The sun goes down at the end of the day and there's a tank of hot water
that won't be (greatly) required but the battery is discharged so the house
supply in the evening is from the grid.

Realistically, the tank will probably only 'sink' 1-2kWh or so before tripping
the thermostat (since it's been topped up overnight on cheap electricity) and
once the thermostat has tripped then power is exported and the inverter will
step back generation to prioritise battery charging.

The instructions with the diverter suggested playing with the threshold level
to reduce the risk of the battery being discharged. I've not noticed a problem
(yet) but the days since it was installed have been sunny.

As normal I'm probably worrying about nothing. I've turned the threshold
down to 150W to see what happens.

[siwilson]

On 19/11/2022 09:22, Stephen Packer wrote:
<snip>

It's all quite complex isn't it? As usual I don't think there is a
single best way of doing things.

I know some systems (Tesla? [1]) also look at the weather forecast to
decide which item to prioritise sending power to. Eg if it's going to be
sunny tomorrow then don't worry too much about charging the backup
battery today.

[1] sorry for swearing [2]

--
/Simon

[Pete Fisher]

ROFL

Did Elon steal your other footnote?
--
Moto Morini 2C/375, Moto Morini 2C/350
Gilera 175 Sport, Husqvarna 401 Svartpilen
"Do not adjust your mind, there is a fault in the reality"

[Stephen Packer]

Ideally I'd like to have a 'system' that does just that, If I could integrate
weather forecasting into the 'system' making the decision on whether
I heat water overnight, or how much charge I put into the battery I could
'save' around 3-5kWh of overnight charging of battery/water heating.

However... with my current tariff of 7.5p/kWh off peak and my export
tariff of 4.1p/kWh that gives me, maybe, 3.4p/kWh 'cost' of making the
wrong decision; 17p per day / £60 a year.

Actually it isn't that much year round since as the days get longer I'll
probably switch the overnight battery charging/water heating off, so I
guess it ends up being £30 a year.

Of course this is all based on having a cheap overnight tariff which
could disappear, but I doubt it. I think the future is going to be time
based tariffing.

[Stephen Packer]

On Saturday, 19 November 2022 at 10:41:24 UTC, Pete Fisher wrote:
> On 19/11/2022 10:32, siwilson wrote:

> > [1] sorry for swearing [2]
> >
> ROFL
>
> Did Elon steal your other footnote?

Made 50% of footnotes redundant.

[Mark Olson]

I have a degree in Electrical Engineering and I can't make heads nor
tails of what is going on here[1].

I suspect the situation is not unlike that when I try to explain
something like a switching power supply design to my usually tolerant
but totally uninterested spouse.

In fact this (solar/renewable power & battery energy storage) is a
subject that I have a considerable interest in.

[1] I'm sure I could, if I drew it all out on paper and studied it
a bit.

--
FJR1300A, GL1000, KLR650A6F, EX250J9A, DR200SE, Vespa Ciao

[siwilson]

On 19/11/2022 13:06, Mark Olson wrote:

>
> I have a degree in Electrical Engineering and I can't make heads nor
> tails of what is going on here[1].
>
> I suspect the situation is not unlike that when I try to explain
> something like a switching power supply design to my usually tolerant
> but totally uninterested spouse.
>
> In fact this (solar/renewable power & battery energy storage) is a
> subject that I have a considerable interest in.
>
> [1] I'm sure I could, if I drew it all out on paper and studied it
> a bit.
>

I've watched a zillion youtubes on various installations and I
definitely don't understand all of it.

--
/Simon

[siwilson]

Find a way to get Home Assistant to get all the info (eg MQTT) and it
looks like they've done a lot of work in this area.

Eg https://www.home-assistant.io/integrations/forecast_solar/

--
/Simon

[siwilson]

On 19/11/2022 10:41, Pete Fisher wrote:
> On 19/11/2022 10:32, siwilson wrote:
>> On 19/11/2022 09:22, Stephen Packer wrote:
>> <snip>
>>
>> It's all quite complex isn't it? As usual I don't think there is a
>> single best way of doing things.
>>
>> I know some systems (Tesla? [1]) also look at the weather forecast to
>> decide which item to prioritise sending power to. Eg if it's going to
>> be sunny tomorrow then don't worry too much about charging the backup
>> battery today.
>>
>> [1] sorry for swearing [2]
>>
>
>
> ROFL
>
> Did Elon steal your other footnote?

Can't remember what I was going to say now. Something derogatory about
Teslas for sure. And maybe a dig at Blaney.

--
/Simon

[siwilson]

This looks fancy:

Example
Get solar production estimate per day as CSV for 52° north, 12° east,
for a installation with a declination of 37° looking south (0°) with
5.67 kWp

curl -H "Accept: text/csv"
https://api.forecast.solar/estimate/watthours/day/52/12/37/0/5.67

--
/Simon

[Stephen Packer]

On Saturday, 19 November 2022 at 13:06:49 UTC, Mark Olson wrote:
> Stephen Packer <stephen...@gmail.com> wrote:
<snip>

> I have a degree in Electrical Engineering and I can't make heads nor
> tails of what is going on here[1].

Same here...

> I suspect the situation is not unlike that when I try to explain
> something like a switching power supply design to my usually tolerant
> but totally uninterested spouse.

This bit sadly confirms what I've considered...

I always felt, when working, that if someone couldn't explain something
to me (to do with mobile telecoms/networks/security) at a level that I
could at least grasp the main concepts then *they* didn't really understand
what they were claiming to be 'expert' in.

So I suspect that I don't fully understand enough about the solar system
and the way I'm trying to prioritise the use of the solar energy
delivered to:
Firstly- Power the house
Secondly- Charge the battery
Thirdly- Heat hot water
Finally- Export anything I can't use.

I'll be honest, part of the reason I typed so much out was to put
my thoughts/understanding on 'paper' to help crystalise it in one
place.

> In fact this (solar/renewable power & battery energy storage) is a
> subject that I have a considerable interest in.

> [1] I'm sure I could, if I drew it all out on paper and studied it
> a bit.

I think I know *roughly* what I'm trying to achieve and to date it
*seems* to be roughly working. I think there is space for more
integration here in the future, especially when we come into the
summer months and there is (hopefully) a *lot* of power I can't
use or store (so I'll chuck car charging into the mix then).

[Stephen Packer]

On Saturday, 19 November 2022 at 20:09:40 UTC, siwilson wrote:
> Find a way to get Home Assistant to get all the info (eg MQTT) and it
> looks like they've done a lot of work in this area.
>
> Eg https://www.home-assistant.io/integrations/forecast_solar/

Gosh. There's fancy.

And it looks like there might be some work done to integrate with
my inverter. Hmm.

Shame that it's years (I think about 25[1]) since I actually *did* anything
with 'software'.

[1] I often used C to process data when I was trying to optimise how
new features were setup on GSM radio networks- integrating 1800MHz
on a 900MHz system, power control on the base-stations, setting handover
boundaries, steering traffic around the network etc. Happy days[2]

[2] A lie, but I was at least young(er) and the future was going to be better
than the past... (I fucking hate this time of year).

[Turby]

On 11/19/2022 5:06 AM, Mark Olson wrote:
> Stephen Packer <stephen...@gmail.com> wrote:
>> On Saturday, 19 November 2022 at 03:14:51 UTC, RustyHinge wrote:
>>> On 18/11/2022 19:36, siwilson wrote:
>>>
>>>> Not sure I follow this.
>

> I have a degree in Electrical Engineering and I can't make heads nor
> tails of what is going on here[1].
>

So I'm not alone. Usually, I'm hampered by Britspeak and obscure TLAs
and ETLAs, but technobabble adds another layer.

>
> In fact this (solar/renewable power & battery energy storage) is a
> subject that I have a considerable interest in.
>

Me too. I'm almost ready to spend some money on it.


--
The erstwhile Thomas
FJR1300, R1200GS & ST1100 (in memoriam)

[Stephen Packer]

On Saturday, 19 November 2022 at 09:22:40 UTC, Stephen Packer wrote:
<snip>
More technobabble.

Leaving the 'offset' where the solar diverter (takes excess solar power and
heats water rather than exporting to the grid) is set at 150W seems to
sometimes run power from the battery into the hot water tank, but not for
long. It seems to switch off on a regular basis and re-sample the amount
of power flowing to grid. So it's more of a problem in theory than in practise
at least, based on a few days of operation.

One slightly worrying, then not so worrying problem cropped up this week with
battery charging. There's a largeish lump (around 50kg) which contains a 5.8kWh
battery connected to the hybrid inverter. This is there (mostly) to capture excess
solar generation and then use it when the sun's gone in, extending (and ideally
removing) the period where I consume power from the grid.

At this time of year there isn't sufficient sun to charge it fully so since I've got
an off-peak period where electricity is about 20% of the cost of peak I've been
charging the battery to about 70% overnight. On Tuesday morning the battery
was only 25% full and on inspection the reason was charging was somehow
capped at 1kW (normally it reached 3.5 kW or so). Further inspection of the battery
data in the 'app' showed the temperature had dipped down to around 11 degrees
before charging started. Being a lithium battery I remember that the temperature
was quite critical to operation and charging, it's specced to work at zero but I guess
there's working and working optimally[1]. I switched the charging on and
watched it... once the temperature went above 15 degrees it started charging at
3kW again.

So putting a battery in a cold unheated loft maybe isn't the best move. I guess
I'll be insulating the exterior wall it's against and maybe adding some kingspan
foam into the roof above it. You live and you learn... plus forget more than you
knew.

[1] Looking up the specs Operating Temp is 0-45 degrees but optimal Operating
Temp is 15-30 degrees.