Payback on solar can vary wildly based on a couple of items...
Where are you? Further north, less power. Days of clear days etc.
What is your price per KW? Some parts of the country have cheap power, others... not so much.
My buddy in Hawaii ended up below 5 years. That is why you see so many there.
Even our condo complex(in Hawaii) purchased solar for the common use areas. You know they looked at the payback pretty hard when you have to justify.
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