Ever considered solar power?

[Brian Howell]

I'm posting this as much because I think it's cool, as I am because I am a proponent of solar electricity:

https://www.google.com/get/sunroof#p=0

[vince koloski]

We installed solar about 3 years ago. The ten 245 watt (24 volt 10 amp) panels, microinverters (which is standard now and it is actually difficult to find a commercial installer who will install an old style inverter), racks and wiring came in at $15,000 gross and $10,000 net after the 30% federal and much smaller state tax credits. The panels settle in at about an 80% efficiency which works out to just a hair over 2k peak generation. We have not paid an electric bill since the installation (save for the $4.85 per month we pay to be hooked into the grid). 

We generate just about 1100k of surplus electricity back into the grid on a yearly basis which PG&E buys back from us. The down side is that they buy it back at wholesale which is 3.5 - 4 cents per KW meaning we make about $40/year from our setup. 

The project sunroof calculator indicates that a 20 year lease would generate $14,000 in savings. 

My back of the envelope calculations indicate that our array will generate about $9,000 in savings over the same time frame. 

I know that they are basing their calculations on heavier electrical usage than ours (we have no children, started using compact fluorescents 25 years ago, have gas stove/water heater/furnace). We also hang our clothes to dry (though I confess to using the 25 year old 110 volt dryer for socks and undies). Our electric bill averaged about $35 a month making our yearly savings including the $40 buyback about $460/year. They are also factoring in a steady 3-5% rise in electricity rates which may be problematic in the near future of cheap natural gas. 

Another downside is the microinverters. They operate by sensing the sine wave from the grid and then releasing the power from the panels. In the case of a power outage, no sine wave from the grid no microinverter power and you have an expensive hood ornament (or roof comb - nod to the Mayans) but are not going to get power. Unless you have a battery backup installed http://www2.enphase.com/global/files/Enphase_Application-Note_AC-Coupled-Battery-Based-Systems.pdf

or have worked out a pre-inverter tap to a few of your panels that sends  24 volt power into your own inverter/charger you are as SOL as any PG&E customer. 

So while we are not going to pay it off in less than 20 years (I will be 79 when that happens), we do have a certain bit of satisfaction in reducing our carbon footprint. I also have a few real estate friends who have told me that solar arrays return 80+% of their cost in increased value to the house. 

Vince Koloski

415-822-8194

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From: Brian Howell <bdho...@gmail.com>
To: Ipse Dixit <Ipse-...@googlegroups.com>
Sent: Tuesday, August 18, 2015 11:30 AM
Subject: [Ipse Dixit] Ever considered solar power?

I'm posting this as much because I think it's cool, as I am because I am a proponent of solar electricity:

https://www.google.com/get/sunroof#p=0

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[Craig Good]

On Aug 18, 2015, at 11:30 AM, Brian Howell <bdho...@gmail.com> wrote:

>
> https://www.google.com/get/sunroof#p=0
>


I’m definitely considering it for my next house, as I plan to do my driving with electricity. The Sunroof calculator came up with what seems like the right number for my square footage (if a bit on the generous side) even though the golden blob connects my roof to the neighbor’s. Such is life in Albany, the city built at 4/5th scale.

Vince:

Am I understanding correctly that you just (ironically) need enough backup battery to generate sine waves for the inverters if you want to not lose power during a daylight blackout?

I guess this just argues for getting a Powerwall as well.




--
--Craig WWJGD?
clg...@me.com http://www.craig-good.com

"It is one of the maladies of our age to profess a frenzied allegiance
to truth in unimportant matters, and to refuse consistently to face
her where graver issues are at stake."
--Norman Douglas

[Matt Fish]

We have solar power through Solar City. I'm not nearly as technical as Vince (wish I was) but bills-wise we essentially break even. On balance we might save $10/month during summer months when it's not excessively hot. If it is excessively hot (like last weekend) we have to use some city power as we run air conditioning. We lease our system for just around $50/month. Our electric bill was around $58/month (averaged over 12 months). We never have excess to sell back to the city, which was how Solar City designed the system. We gain almost nothing, we lose nothing. The earth gains ...? Maybe Brian can help me calculate how little good we are actually doing the earth. :)

 

We have amazing insulation (closed cell spray foam layer with bats, double pane windows) so our A/C doesn't have to work excessively hard. (We aced our blower door test.) It's a 13 or 14 seer rated A/C if I remember correctly, which could have been more efficient for sure. We have a white-ish roof. We failed to add a radiant barrier on the roof during construction (five years ago). That was a huge oversight. For probably no more than a hundred bucks or so, we could have reduced our interior temps about 10 degrees if we'd been smarter and installed a radiant barrier. (Home depot sells OSB panels with a radiant barrier on them for a couple bucks more than regular OSB panels.) 

Just like Vince, we are totally out of luck when there is a power outage. All that power and no way to use it. Enter Elon Musk (who started Solar City) again with a Tesla-style home battery system. I wish for one of these as a stocking stuffer next christmas. 

If we ever sell our house I guess that having solar panels would be at least a nice-to-have for almost all buyers. 

Note to anyone thinking about leasing a system: Get one large enough to cover any future electrical usage, such as plug-in vehicles. Our system is just under the size we need and I wish it was slightly larger so we could sell power back to the power company. Note to anyone with a plug-in vehicle: charge the batteries in the middle of the night for the lowest electric rates. 

Like Craig, I had intended to buy a plug-in hybrid. For now those cars are too pricey for us. It's my belief that plug-in hybrids, along with a beefier home solar system that can power the vehicles, will be the most significant way we can reducing our carbon footprint. But let's be clear: The only way to make serious carbon emissions reductions is to generate everyone's power with renewables or natural gas or waves or nuclear or take your pick. Given the extremely low price of coal, I am skeptical this will happen in my lifetime. 

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[Matt Fish]

As a follow-up, I thought I'd share my electrical generation for both today and for 2015 year-to-date. Solar City has a wireless monitoring device that hooks up to our local network. There are two attached images. They are both for solar power generation on my roof. Incidentally, today is August 18, 2015, and we have 13.3 hours of daylight and 61% cloud cover in Los Angeles.  

[Craig Good]

Does Solar City do sales as well, or is it only a lease arrangement like this?

On Aug 18, 2015, at 18:00 PM, Matt Fish <mattfi...@gmail.com> wrote:

> As a follow-up, I thought I'd share my electrical generation for both today and for 2015 year-to-date. Solar City has a wireless monitoring device that hooks up to our local network. There are two attached images. They are both for solar power generation on my roof. Incidentally, today is August 18, 2015, and we have 13.3 hours of daylight and 61% cloud cover in Los Angeles.

--
--Craig WWSJD?
clg...@me.com http://www.craig-good.com
Crazee Eddee! His prices are INSANE!!

[Matt Fish]

Solar City has three flavors: Zero down lease, lease with down payment (I can't recall the precise percentages), and full purchase. Salt to taste.

[Vince Koloski]

Craig,

That's basically correct. The powerwall (or other battery system connected to you solar array/microinverters) acts as a mini-grid system that gives the inverters the right signal and they continue to supply power. In the case of battery backup systems the power shunts only to the batteries. It was explained to me that the inverters that tie into grid systems (in the old days large inverters that took your total array output, turned it into AC and dumped it into the grid; nowdays the micrinverters on each panel that do the same) all used this sensing technology to avoid "islanding." Islanding was where the power was out but your solar array was pumping power into the grid creating an island of power that could then be dangerous to anyone working on restoring power. That's also why solar arrays require a power cut off switch that can be thrown to physically stop the power from reaching the grid. 

One good news aspect of battery systems is that they can be put in place as an after install upgrade and can vary in size depending on your desires/buget