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I couldn't make the math work on home battery storage. The difference between peak and non-peak is 37 cents, so if I shift 5KW of usage from peak to non-peak, t

I couldn't make the math work on home battery storage. The difference between peak and non-peak is 37 cents, so if I shift 5KW of usage from peak to non-peak, that's $675/year in power savings, but the cost to install a whole house system that could shift my home's peak usage would be in the $10,000 range. If my next EV can act as a battery for the house, that may shift the economics since I'd have a "free" 80KWh+ battery (and inverter? Not sure if the car acts as an inverter too), so would only be paying for the wiring. As far as I know, my utility won't buy back power at peak rates, the best I could get is a credit to offset my power usage, which only makes sense if I have solar (which is not simple since I live in a condo without a lot of roof area even if I could get permission for solar)

oliwarner 3y ago
Yeah, having a functional energy market definitely helps make these things make sense. We have half-hourly, bidirectional metering, and being able to save solar and sell it at a good rate means the payback period is looking like 7 years for us. Our grid is also experimenting with paying people to borrow their batteries for predicted high usage events, up to £25 for one event. I guess this means nothing if you can't access it but hopefully it's a model that spreads.
romski 3y ago
Ya agreed about that cost for a backup install - there are some interesting new options that should be less labor from an electrician. https://us.ecoflow.com/products/delta-pro-transfer-switch https://us.ecoflow.com/products/delta-pro-transfer-switch
- Johnny555 3y ago
  Yeah, there are a lot of more affordably priced solutions out there, but they still need a subpanel or similar cutover switch to be installed and that's where a lot of the electrician's cost is. Plus, the inexpensive ones like this $3300 Ecoflow are 120VAC (up to 3600W), so if you want to be able to power larger household loads like an oven or heat pump, you need to buy two (or more) of them (or a bigger unit), which doubles the price and gets you into the price ranger of other whole-house systems like a Powerwall or Enphase. With the 120VAC unit, about all I could power in my house is lights, TV's, and maybe some small kitchen appliances, which limits how much power I could shift off of peak, maybe a KWh or two, which makes it harder to get any payback on the investment. Unless the spread between peak/offpeak power prices becomes larger, I'm not sure that battery storage is going to be a worthwhile investment (for me). Or maybe if the utility bought back power at a reasonable rate during peak periods as the other poster's power company does...But the California PUC doesn't seem to be interested in incentivizing that model.

oliwarner 3y ago

Yeah, having a functional energy market definitely helps make these things make sense. We have half-hourly, bidirectional metering, and being able to save solar and sell it at a good rate means the payback period is looking like 7 years for us. Our grid is also experimenting with paying people to borrow their batteries for predicted high usage events, up to £25 for one event. I guess this means nothing if you can't access it but hopefully it's a model that spreads.

romski 3y ago

Ya agreed about that cost for a backup install - there are some interesting new options that should be less labor from an electrician. https://us.ecoflow.com/products/delta-pro-transfer-switch https://us.ecoflow.com/products/delta-pro-transfer-switch

Johnny555 3y ago
Yeah, there are a lot of more affordably priced solutions out there, but they still need a subpanel or similar cutover switch to be installed and that's where a lot of the electrician's cost is. Plus, the inexpensive ones like this $3300 Ecoflow are 120VAC (up to 3600W), so if you want to be able to power larger household loads like an oven or heat pump, you need to buy two (or more) of them (or a bigger unit), which doubles the price and gets you into the price ranger of other whole-house systems like a Powerwall or Enphase. With the 120VAC unit, about all I could power in my house is lights, TV's, and maybe some small kitchen appliances, which limits how much power I could shift off of peak, maybe a KWh or two, which makes it harder to get any payback on the investment. Unless the spread between peak/offpeak power prices becomes larger, I'm not sure that battery storage is going to be a worthwhile investment (for me). Or maybe if the utility bought back power at a reasonable rate during peak periods as the other poster's power company does...But the California PUC doesn't seem to be interested in incentivizing that model.