What's charging up the battery?
Normally, the utility, PG&E.
Is it there just for emergencies? Just long enough for the generator to kick in?
The primary purpose is a behind-the-meter (no export capability) uninterruptible power system. We didn’t want to run the generator continuously for a small load, but we did want continuous power. So the batteries facilitate that. Once installed, however, it turns out I can volunteer to participate in the "OhmConnect" program and get paid for reducing utility load when supply is short. I hope to automate that... my first attempt worked, but was cumbersome to keep online. We have enough storage for about 24 hours of background load (no air conditioning or electric oven use... just fridge, freezer, lights, etc.) When PG&E goes away for a PSPS (public safety power shutdown, AKA the wing is blowing 40 MPH or more) then the generator can run 2 hours a day to recharge the batteries for another 24 hours.
I would have thought with the power rates in CA that solar would have made more sense there.
It would have... but as I noted above, once you're on the Electric Vehicle rate (EV rate), off-peak power is about 1/3 the cost of peak power... it's a simple matter of programming to have the batteries shallow cycle daily to run the house on the inverter during the six-hour peak period, and recharge during the off-peak period. That cuts cost of electricity by about 2/3.
Has CA cut out the incentives for solar?
There's no unified answer for California, as we have a polymorphous system. The three, large IOUs (investor owned utilities) are regulated by the CPUC, California Public Utilities Commission. The CPUC has a significant progressive agenda with transfer payments galore, making incremental use for deemed-to-be wealthy people quite expensive. If you're paying that tier three rate, then solar is a bargain. But yes, the IOUs are doing everything they can to reduce solar incentives, both up front and ongoing.
The rest of the state has municipal utilities, including the enormous Los Angeles Department of Water and Power. They are very loosely regulated by the state legislature, and it's almost laissez faire: they are autonomous municipal authorities that make up their own rules, often as they go along... and rates vary widely from REALLY cheap, like Imperial Irrigation District, where power is a byproduct, to really not cheap, like Silicon Valley's municipal utility, or Alameda Island's, where admin costs are significant compared to kilowatt-hours delivered.
Solar would be helpful here to a point. In the summer the rates go up after so many kWh, which means as it gets hotter we pay more for electricity as the AC is running more, so we go over the kWh threshold.
Depending on the rate structure, battery storage might be a viable economic solution.
If one uses the Georgia Power pricing rate for EV vehicles, solar would really help as they give you power at night (1 cent / kWh), but you pay 20 cents/kWh during the hot part of the day. I was wondering if that delta in rate would pay for batteries (charge up at night and discharge during the day), but the Tesla batteries are rather pricey.
Yeah, Tesla is uneconomic. I think we provided more capability (more features) than Tesla, at about 1/3 the price per kiloWatt. But then... it's not as sleek and pretty a cabinet. I guess if that was important, I could buy a sleeker cabinet, but I had a suitable basement room, so that's where the batteries and charger/inverter live. The transfer switch and NG generator are outdoors, near the service entrance.
I was thinking about solar, but we need something somewhat custom, as we have a standing rib roof that's a design feature of our home. Flexible panels that fit between the standing ribs would be cool looking, but are more difficult to obtain (possibly only via custom fabrication, which is more expensive but not unconscionable). But, with storage in place, and looking at EV rates... well, solar isn't cost-effective until/unless the EV price structure changes.
What the entire system needs is more storage, as the California grid goes infeasible without PAYING Arizona to take our power at times. That's just goofy. The Germans did this better, I think... they thought it through, and created incentives for both storage *and* solar/wind... recognizing that success with non-conventional generation would create a necessity of storage... so why not build out the generation and storage systems logically and together. We have yet to come to that "aha!" realization here, it seems... in fact, the utilities fight consumers on storage, assuming you want to arbitrage them, buying cheap power and selling back expensive power, but at margins greater than they'd like to pay, and without a profit incentive for them. Those are fixable problems, but not readily in a polymorphous system, unless someone in the legislature (or California Energy Commission) wants to set aside politics (!) and put on their engineering/public policy hat. I'm not optimistic that will happen short of grid collapse crises.
Paul
