4 ms·

Shift usage to daytime and rely on battery storage.

by newsclues 11mo ago

UltraSane 11mo ago
Batteries are very expensive.
- newsclues 11mo ago
  Couple used car batteries or usb batteries are cheap. Enough to keep the lights on, a fan or charging a phone. Not to run an AC or dishwasher but enough for the basics.
- triceratops 11mo ago
  They're cheap and getting cheaper. Your info is from 2021. Things change quickly in this industry.
  - UltraSane 11mo ago
    Batteries are absolutely not cheap for what they store.
    - triceratops 11mo ago
      How much do you think they cost?
      - UltraSane 11mo ago
        Installed costs for residential battery storage typically range from $800-1,200/kWh in the US market as of 2024-2025. ROI for 24/7 solar+battery is negative in almost all residential cases using current technology and prices.
        triceratops 11mo ago
        Let's assume the lower end of that range - $800/kWh and take the example of Arizona. https://www.aps.com/en/Residential/Service-Plans/Compare-Service-Plans/Time-of-Use-4pm-7pm-Weekdays https://www.aps.com/en/Residential/Service-Plans/Compare-Ser... The difference between off-peak and on-peak rates there is about $0.21/kWh in the summer and $0.29/kWh in the winter, so assume an average delta of $0.25/kWh. Assuming no solar panels, if you charge the battery on the grid at off-peak rates and discharge it completely at on-peak rates, you break even after using about 3200kWh. Assuming 2 kWh used every day during peak rates that's a breakeven period of 4.38 years. Maybe my calculations are wrong somewhere, and I'd love to learn if that's the case. I also acknowledge some big assumptions: namely, that you will always need to use all your stored energy day at the peak time (reasonable in the summer when the AC is running) and that you can use all your battery power for those loads instead of grid power. On the other hand electricity rates tend to go up over time and batteries last for years.
        UltraSane 11mo ago
        3.5 cents per KWh is exceptionally cheap and does seem to give a reasonable payback period for cheap enough batteries.
        triceratops 11mo ago
        No I goofed a bit too, by assuming 2kWh used every day but $800 in installation cost (which is for 1kWh). Fixing that error increases the payback to 8.76 years/kWh of installed battery. But only if you assume rates don't change for all of those ~9 years. But rates will likely increase. So will the delta between off-peak and on-peak rates. I think the true payback period is between 5 and 8 years.
davyAdewoyin 11mo ago
For my experience a lot of installations really doesn't have much battery capacity cause batteries are pretty expensive at least here in Nigeria, but a lot of people are really happy with the system as long as they get electricity even if it's only during the day.

Shift usage to daytime and rely on battery storage.

UltraSane 11mo ago

Batteries are very expensive.

newsclues 11mo ago
Couple used car batteries or usb batteries are cheap. Enough to keep the lights on, a fan or charging a phone. Not to run an AC or dishwasher but enough for the basics.
triceratops 11mo ago
They're cheap and getting cheaper. Your info is from 2021. Things change quickly in this industry.
- UltraSane 11mo ago
  Batteries are absolutely not cheap for what they store.
  - triceratops 11mo ago
    How much do you think they cost?
    - UltraSane 11mo ago
      Installed costs for residential battery storage typically range from $800-1,200/kWh in the US market as of 2024-2025. ROI for 24/7 solar+battery is negative in almost all residential cases using current technology and prices.
      - triceratops 11mo ago
        Let's assume the lower end of that range - $800/kWh and take the example of Arizona. https://www.aps.com/en/Residential/Service-Plans/Compare-Service-Plans/Time-of-Use-4pm-7pm-Weekdays https://www.aps.com/en/Residential/Service-Plans/Compare-Ser... The difference between off-peak and on-peak rates there is about $0.21/kWh in the summer and $0.29/kWh in the winter, so assume an average delta of $0.25/kWh. Assuming no solar panels, if you charge the battery on the grid at off-peak rates and discharge it completely at on-peak rates, you break even after using about 3200kWh. Assuming 2 kWh used every day during peak rates that's a breakeven period of 4.38 years. Maybe my calculations are wrong somewhere, and I'd love to learn if that's the case. I also acknowledge some big assumptions: namely, that you will always need to use all your stored energy day at the peak time (reasonable in the summer when the AC is running) and that you can use all your battery power for those loads instead of grid power. On the other hand electricity rates tend to go up over time and batteries last for years.
        UltraSane 11mo ago
        3.5 cents per KWh is exceptionally cheap and does seem to give a reasonable payback period for cheap enough batteries.
        triceratops 11mo ago
        No I goofed a bit too, by assuming 2kWh used every day but $800 in installation cost (which is for 1kWh). Fixing that error increases the payback to 8.76 years/kWh of installed battery. But only if you assume rates don't change for all of those ~9 years. But rates will likely increase. So will the delta between off-peak and on-peak rates. I think the true payback period is between 5 and 8 years.

davyAdewoyin 11mo ago

For my experience a lot of installations really doesn't have much battery capacity cause batteries are pretty expensive at least here in Nigeria, but a lot of people are really happy with the system as long as they get electricity even if it's only during the day.