Re: [HACK-ADL] Mains power measurement

[Ken]

No, I don't have solar panels yet.  Have to do some sums to see if it is worth it for me.
If the same LED flashes on both import and export, you wouldn't know which way the power was going.
That seems pretty useless.
But don't you get a totally different meter if you have solar?
Presumably you can get info out of your solar system, but maybe not easily.
A guy at work has a Bluetooth output from his, but that cost him heaps.
He logs power level and sends it to a public website for such data.  Then he can see graphs etc of his generation as well as that of other people.

(I've changed the subject in case this thread continues on for a bit.)

Ken.

On 9 July 2012 16:33, Scott B <solar....@gmail.com> wrote:

yep 100W load would be 36 seconds between flashes.

so if you counted flashes per (say) 5 minute period, you would have about a 12W accuracy - which should be plenty accurate enough to know whats going on.

Generally a house will run at 50 - 100W background (a couple TV's etc on standby, a PVR, a modem, perhaps a second wireless router, clock radio's etc), if a fridge kicks in it that will be another 100 - 150W, and as soon as a TV goes on, heaters cooking appliances etc it sky-rockets from there.

Do you have solar panels? I haven't checked mine yet, but i suspect the same LED flashed for import and export, so this could make things a little more complex.

On Monday, July 9, 2012 3:40:19 PM UTC+9:30, Ken wrote:

Sorry, yes Scott.
So at 100W load, the updates would be every 36 seconds.  (Please check my maths.)
It is probable that most of the time I'll be using enough juice to get reasonably short update periods.
I'll give it a go to find out.

On 9 July 2012 15:27, Scott B <solar....@gmail.com> wrote:

are you sure its one pulse per kWh? not 1 pulse per Wh?

On Monday, July 9, 2012 11:57:59 AM UTC+9:30, Ken wrote:

Well I've moved into my new house and had a peek at the electricity meter.
It has a one-pulse-per-kwhr LED, and another one whose purpose I'm not too sure of.

But when I think on it more, while it would be nice to graph the exact usage over time, the LED isn't going to update too often under light load/usage.

So I'd still like a power reading that updates frequently.
The unit I have does it every 6 seconds, but isn't hugely accurate, and doesn't interface usefully to a computer.  (Only gives a history, in a proprietary format.)

I think the electronics and maths etc are too much hassle to do from scratch (for a lazy person like me).
-Needs to measure 3 phases of current, power factor, voltage, calculate instantaneous power on each, then send to a remote point.

So if anyone is aware of any gear that can be bought for this purpose (at hobby type prices), I'd like to hear from you.
Failing a bought unit, I'd need a fairly fast micro to measure all those values, compare phase and calculate, 3 times over.

Ken.

On 28 June 2012 13:23, Ken <k...@waggies.net> wrote:

Does anyone have experience with modern electicity meters?

Silicon Chip magazine has a circuit-ideas article on reading, sending, & displaying, the one pulse per watthour LED on electricity meters.
(I didn't know there was one!)
It uses a Picaxe to send over 433MHz, and display on 7-segment digits.

My current electricity meter has the old turning disk.
The one in my new house is modern.

I have a gadget that measures the currents in three phases and sends to a console inside.
But it is not too accurate (doesn't measure voltage or current phase), and doesn't connect to a PC too well.

I feel a project coming on.

Ken.

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[Scott B]

you do get a different power meter, but it looks pretty much the same, you just get a few more functions to scroll through.

He is probably using PVoutput.org? my systems are hooked up to it for live data (along with most of the guys at work and some of our commercial buildings- something like 70kW in total).

I am using CMS inverters, which has a RS-232 port, I ended up buying a cheap ($250) 7" laptop that polls the two inverters and uploads the data, I have also got an arduino to upload data, but haven't had time to make it talk to the inverter yet.

The laptop wakes itself every 5 minutes in daylight hours to take the reading then goes back to sleep, so it end up using bugger all power - on batteries it will last 2-3 days.

as for are panels worth it... I got mine while the 52c feed in was still available, and I was on target to pay off the first (1.6kW) system in under 3 years, and the second (1.9kW) in about 4 - they were not cheap 'no-name' systems either. However as I'll be moving house in about 12 months (the feed in rate will halve), and the wife is now at home most of the time looking after the 10month old daughter it is probably going to take more like 5 years to pay itself off (or less if prices keep rising).