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Is there a reason you did the math with a 13.5kWh battery? Do you heat a large house electrically? Do you need to charge an EV at night off that battery? Most

Is there a reason you did the math with a 13.5kWh battery? Do you heat a large house electrically? Do you need to charge an EV at night off that battery? Most people can get away with a significantly smaller battery - if your goal is to just get a normal house through a single night. That goal can be achieved pretty economically, especially if you're willing to use grid electricity on mornings with little sun on your panels or nights with unusually high demand.

gwd 3y ago
Basically the quote we got from the local company gave us the option of a 10kWh non-Tesla battery for about £10k and a 13.5kWh Tesla battery for £12k. The math doesn't change that much between the two. I had also looked into battery sizing previously based on our annual usage; but that was over 3 years ago so I don't remember what I came up with.
XorNot 3y ago
What is the point of a grid battery if you don't heat your house electrically, particularly from the point of view of climate change which is meant to be the real reason we're doing this.
- pbmonster 3y ago
  The difference is mostly financial. Lots of people around me install/upgrade their rooftop PV system right now, and most of them get a small battery to make it through the night. Both a new PV system and a battery is subsidized, and the money is easy to get. Heatpump upgrades to existing houses are much more expensive, and for some reason the subsidies are incredibly complicated to get, and there's no guarantees for exactly how much you'll get approved. Baby steps, I guess. Financial incentives (and the extreme price drop in batteries and PV modules) mean we're starting with switching normal household electricity consumption to renewables. We'll do household heating... some other time.
  - XorNot 3y ago
    I'm pretty skeptical "energy through the night" is financially viable for anyone. Whenever I've looked into it, the cost-per-kwh on a battery blows away any savings over the cost of just paying for off-peak electricity. Which makes sense of course: if it didn't, then it would be more cost-effective for larger players to simply build grid batteries and arbitrage the power cost down to parity. The only real value I've seen is when your selling your own battery capacity under grid-stabilization programs (where some other power company is managing virtual power plants). And I'm still fairly skeptical if that's even a sensible business model (i.e. how much real estate cost can you be saving versus the costs of installing distributed batteries as opposed to centralizing them?)

gwd 3y ago

Basically the quote we got from the local company gave us the option of a 10kWh non-Tesla battery for about £10k and a 13.5kWh Tesla battery for £12k. The math doesn't change that much between the two. I had also looked into battery sizing previously based on our annual usage; but that was over 3 years ago so I don't remember what I came up with.

XorNot 3y ago

What is the point of a grid battery if you don't heat your house electrically, particularly from the point of view of climate change which is meant to be the real reason we're doing this.

pbmonster 3y ago
The difference is mostly financial. Lots of people around me install/upgrade their rooftop PV system right now, and most of them get a small battery to make it through the night. Both a new PV system and a battery is subsidized, and the money is easy to get. Heatpump upgrades to existing houses are much more expensive, and for some reason the subsidies are incredibly complicated to get, and there's no guarantees for exactly how much you'll get approved. Baby steps, I guess. Financial incentives (and the extreme price drop in batteries and PV modules) mean we're starting with switching normal household electricity consumption to renewables. We'll do household heating... some other time.
- XorNot 3y ago
  I'm pretty skeptical "energy through the night" is financially viable for anyone. Whenever I've looked into it, the cost-per-kwh on a battery blows away any savings over the cost of just paying for off-peak electricity. Which makes sense of course: if it didn't, then it would be more cost-effective for larger players to simply build grid batteries and arbitrage the power cost down to parity. The only real value I've seen is when your selling your own battery capacity under grid-stabilization programs (where some other power company is managing virtual power plants). And I'm still fairly skeptical if that's even a sensible business model (i.e. how much real estate cost can you be saving versus the costs of installing distributed batteries as opposed to centralizing them?)