Quote:
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The general range for a solar battery's useful lifespan is between 5 and 15 years. If you install a solar battery today, you will likely need to replace it at least once to match the 25 to 30 year lifespan of your PV system.
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https://www.energysage.com/solar/sol...-solar-panels/
I have provided sources showing that the average solar installation in the Phoenix area would cost $15,000 and have an ROI of eight years.
Enough batteries to run the air conditioning for three hours would also cost $15,000, making the ROI sixteen years--longer than the expected life of the batteries.
So, before you pay them off, you already replace them. If you replace them then the ROI is now twenty-four years, but that is probably longer than the batteries will last, and is approaching the anticipated life expectancy of the solar panels.
If installing batteries becomes 10% cheaper and they last 10% longer you should break even on them.