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drees
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Re: How to increase the *fraction* of roofs covered?

Mon Feb 24, 2014 1:09 am

Randy wrote:If your scenario was true and in the daytime each and every customer generated their electricity and did not rely on the grid at all during the daylight hours, that would (of course) result in a near zero flow on the grid during those hours. Existing large scale generating plants, however, would still need to be running at minimum output because as the sun starts to go down and solar output drops off, a "new" system peak is created from a utility generation perspective as people get home from work and fire up everything at home....In fact, my personal opinion is that this evening peak will just be a little bit less in the future than the current peak load we see in the afternoon.

Yes, the evening peak is easily seen in California during non-summer months and it's quite predictable. In the summer, the evening peak is drawfed by the mid-afternoon peak caused by peak air conditioning loads.

http://www.caiso.com/Pages/TodaysOutlook.aspx

Between the two of them, though, it's pretty clear that not a lot of storage will be required to substantially smooth that out. 2-3 hours of storage is going to go a long ways towards smoothing that peak out.

What is exciting is that all the solar hitting the grid will soon make electricity cheap in the middle of the day. As far as power plants and having to ramp up - the spread between min/max is around 10 GW to 27 GW on a hot summer day. Solar isn't going to be reducing this spread, but it will be reducing the amount of time spent at higher loads. Modern gas turbines (which California has a lot of) are very good at ramping up and down quickly, so I'm not convinced that solar is going to be a big problem for some time to come yet.

As far as how much solar PV could fit on my house, currently I only have about 3.2 kW (DC) of solar PV, but if I could completely cover my roof I probably could get at least 12 kW of PV up on the roof with standard efficiency modules with about half facing south and the other half facing east. Annually, this would generate close to 20,000 kWh of electricity a year, or about double my current annual electricity usage (which includes the LEAF). The extra would be enough to more than offset all our natural gas usage (assuming it was replaced with plain resistance heating, heat pumps would be far more efficient) and electrify our other vehicle, too, with lots of electricity to spare.

But is there any financial incentive to even get close to that level of production? Not really. At the most, I might add another 2-3 kW of PV at some point in time, but that would require an expensive main service panel upgrade which would cost as much as the additional PV system would cost due to the trenching that has to be done to upgrade the underground utility feed.
'11 LEAF SL Powered By 3.24 kW Enphase Solar PV

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RegGuheert
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Location: Northern VA

Re: How to increase the *fraction* of roofs covered?

Mon Feb 24, 2014 6:45 am

DNAinaGoodWay wrote:http://www.solarroadmap.com/producing-your-own-energy-with-a-community-solar-garden/

Here's a starting point for you. Now that I look into it, there are several states that are allowing this to happen, and more coming on board, so see if you can get it going where you are. Wave of the future baby!
Wow! Thanks!

That's a great article which points to workable solutions to the barriers we all face toward utilizing as much of our available roof space as possible.

I'll have to see how to try to promote something like this in VA.
RegGuheert
2011 Leaf SL Demo vehicle
10K mi. on 041413; 20K mi. (55.7Ah) on 080714; 30K mi. (52.0Ah) on 123015; 40K mi. (49.8Ah) on 020817; 50K mi. (47.2Ah) on 120717; 60K mi. (43.66Ah) on 091918.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

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