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Average US home power consumption: 30 KWh/day. Assuming an average of 4 solar hours per day, you would need a solar system capacity of approximately 7.5 kW to

Average US home power consumption: 30 KWh/day. Assuming an average of 4 solar hours per day, you would need a solar system capacity of approximately 7.5 kW to 12.5 kW. Individual solar panels produce 250-400 watts. So, conservatively, 50 panels. Installed, that's currently about $25,000, including inverter but not battery backup. Battery backup will cost maybe $15,000 more. So, the whole installation is about $40,000. This is with no grid connection, power sales, or incentives. Not too bad. Costs about the same as a car. Median US house price is $412,300.

toomuchtodo 2y ago
Did you factor in 30% federal tax credit? https://www.energy.gov/eere/solar/homeowners-guide-federal-tax-credit-solar-photovoltaics https://www.energy.gov/eere/solar/homeowners-guide-federal-t...
- Animats 2y ago
  No.
nightski 2y ago
In my state electricity costs about $0.089/kWh. We spend about $100/mo on electricity total which comes out almost exactly to your 30kWh/day figure (with a $23.15 connection charge included). Invested that 40k would conservatively cover over 2x our electricity bill without touching the principal (inflation adjusted). That's a pretty hard sell for solar. Obviously incentives will improve things but it just seems less financially risky to use grid power.
- bdhdbebebeb 2y ago
  10 years ago for me math didn't add up for batteries and offgrid but it did add up for solar. Offgrid added up if you are already offgrid so that ongrid becomes a big expense when comparing.
- fred_is_fred 2y ago
  That’s where my math went. 30k- 12 years to get back to the investment. 30k in the s&p is worth a lot more than 30k…
  - toomuchtodo 2y ago
    Residential solar PV and batteries should be treated as a bond return and performance, and not equivalent to investment in equities, as it is insulating you from future utility rate increases. https://www.bogleheads.org/forum/viewtopic.php?t=411421 https://www.bogleheads.org/forum/viewtopic.php?t=411421
bdhdbebebeb 2y ago
Not too bad. You need a lot of space for 50 panels. You need to live in a large suburbian house or rural and stick them on a barn or on the ground. Clearly to meet demand we need solar farms and grids for most people.
GaggiX 2y ago
~500$ for a 250/400W panel seems absurd, here in Italy you can buy a 500W solar panel for 100€ without effort or less. Given that you can buy a pallet of them, you can probably pay less than 100€ per 500W, I have found deals down to 77€ per 550W panel with pallets of 31 (31x550=+17k at 2405€), shipment included, and I'm talking about new half cell panels, not old stuff.
ifdefdebug 2y ago
Your numbers are way off (at least for Europe). Panels are 580 W peak now and cost < €150. Battery < €1000 per kWh. Prices still dropping.
- Animats 2y ago
  I was quoting an installed price. Panels are less than half the installed cost now. If the "solar roof" people ever get their act together, that might change.
knappe 2y ago
We are in the process of installing a 13 kwH system which is 31 panels at 430 watts with two Tesla power walls. Total cost (with snow guards) is just shy of 60k. The backup batteries are where this really shines. Our power provider had a blackout of 25 hours in April and if we were 6 blocks south, it was an entire week. The true cost of the system will be approximately half this after rebates and is more like 32k. The rebates are so good between Fed, State and the power company that we almost got the backup batteries for free.

toomuchtodo 2y ago

Did you factor in 30% federal tax credit? https://www.energy.gov/eere/solar/homeowners-guide-federal-tax-credit-solar-photovoltaics https://www.energy.gov/eere/solar/homeowners-guide-federal-t...

Animats 2y ago
No.

nightski 2y ago

In my state electricity costs about $0.089/kWh. We spend about $100/mo on electricity total which comes out almost exactly to your 30kWh/day figure (with a $23.15 connection charge included). Invested that 40k would conservatively cover over 2x our electricity bill without touching the principal (inflation adjusted). That's a pretty hard sell for solar. Obviously incentives will improve things but it just seems less financially risky to use grid power.

bdhdbebebeb 2y ago
10 years ago for me math didn't add up for batteries and offgrid but it did add up for solar. Offgrid added up if you are already offgrid so that ongrid becomes a big expense when comparing.
fred_is_fred 2y ago
That’s where my math went. 30k- 12 years to get back to the investment. 30k in the s&p is worth a lot more than 30k…
- toomuchtodo 2y ago
  Residential solar PV and batteries should be treated as a bond return and performance, and not equivalent to investment in equities, as it is insulating you from future utility rate increases. https://www.bogleheads.org/forum/viewtopic.php?t=411421 https://www.bogleheads.org/forum/viewtopic.php?t=411421

bdhdbebebeb 2y ago

Not too bad. You need a lot of space for 50 panels. You need to live in a large suburbian house or rural and stick them on a barn or on the ground. Clearly to meet demand we need solar farms and grids for most people.

GaggiX 2y ago

~500$ for a 250/400W panel seems absurd, here in Italy you can buy a 500W solar panel for 100€ without effort or less. Given that you can buy a pallet of them, you can probably pay less than 100€ per 500W, I have found deals down to 77€ per 550W panel with pallets of 31 (31x550=+17k at 2405€), shipment included, and I'm talking about new half cell panels, not old stuff.

ifdefdebug 2y ago

Your numbers are way off (at least for Europe). Panels are 580 W peak now and cost < €150. Battery < €1000 per kWh. Prices still dropping.

Animats 2y ago
I was quoting an installed price. Panels are less than half the installed cost now. If the "solar roof" people ever get their act together, that might change.

knappe 2y ago

We are in the process of installing a 13 kwH system which is 31 panels at 430 watts with two Tesla power walls. Total cost (with snow guards) is just shy of 60k. The backup batteries are where this really shines. Our power provider had a blackout of 25 hours in April and if we were 6 blocks south, it was an entire week. The true cost of the system will be approximately half this after rebates and is more like 32k. The rebates are so good between Fed, State and the power company that we almost got the backup batteries for free.