Yep, rewarding me for behavior I was going to pretty much do anyway? God bless America.
My ROI was 8-10 years, but it’s difficult to model because of electric rates, non-linear panel degradation over time, changing time-of-use windows, and possible usage increases over time (like do you have aging parents moving in?)
This is how I modeled it (simplistic):
Total electricity usage 1yr ~10,000 kWh
Average price of electricity: $0.22/kWh
(Range $0.18-$0.36 depending on time of day, we do a really good job of not using anything 1pm-7pm).
Total cost per month: $183.33 ($2200/yr)
Total cost solar panels after tax credit: $16,520 (7.2kW) - two systems purchased 3yrs apart (current Tesla price is $14,430 for 7.6kW)
“Monthly payment”* for panels @ 4% interest x 9 years = $182.40.
*paid cash
So break even is 9 years with no changes.
A 10% increase in my electric cost ($0.22 to $0.242) = break even at year 8
A 10% increase in electric usage AND 10% increase in electric costs = break even point at year 7
My utility (PG&E) is in bankruptcy and has multiple liabilities for causing wildfires, it is highly likely ratepayers will be required to face some additional rate increases in the coming years. Adding a second solar system was a hedge against that (and increased usage, possible EV car in a few years).
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