[The MAGA-Deplorian]

Ery logical. Question for you because I’ve never seen a real answer. What is the expected life span of a solar panel and does its energy output degrade over time? So you are getting 50% return now. Will it be that way by the time it pays for itself in 10 years? And what the maintenance required for it (i.e. windex the panels twice a year? Replace batteries?)
Thanks

[Tell It Right]

My math on it paying for itself in a decade assumes the degradation in efficiency you speak of.

My solar batteries have a 19-year warranty (really it's 7,000 depths of discharges, but since that happens once per day that's 7,000 days which is slightly over 19 years) with a gradual degradation to 50% capacity at the end of the warranty. And the warranty requires I don't discharge them more than 80% (making my 30 kWh of storage a usuable 24 kWh storage), but I discharge them only 70% to get more life out of them (making it effective 21 kWh storage). At the end of the 19 years it'll be 15 kWh (12 kWh usable).

My panels have a 25-year warranty with a gradual decline in efficiency to 70% at the end of the warranty. So my current 10 kW of solar will be 7 kW at the end of 25 years.

As far as maintenance goes, it depends. I have no trees near my house -- no sap or such dripping on them requiring me to clean them. Plus, my roof that they're on is at a steep pitch -- making it so that pollen and such doesn't build up as much. A rain cleans them, particularly at the steep pitch. Plus, snow and ice gives it a deep clean when the snow melts and washes off. I've had them a year and they still produce 10 kW like they did originally with no cleaning.

Windex is a bad substance for solar panels. The best cleanser is plain water. I expect to have to clean them every few years with water and a soft rubber brush. I can reach them from my deck with a ladder with this: https://www.amazon.com/dp/B07HGJ9TRP/ref=redir_mobile_desktop?_encoding=UTF8&aaxitk=b98379cc14aaca8ef5fcc6424885f81a&hsa_cr_id=1036087300401&pd_rd_plhdr=t&pd_rd_r=f86ea3e2-ea65-4322-a976-15a1982af7b0&pd_rd_w=iCRgk&pd_rd_wg=rxQQh&ref_=sbx_be_s_sparkle_mcd_asin_2_title.

If I upgrade it and add solar panels (something I might do if I get an EV to help me hedge against gasoline price inflation like I'm already hedged against power price inflation and natural gas inflation), the only roof space I left for more panels is on a slight pitch (not a steep pitch), which means they might need cleaning once per year. Because of the slight pitch they're out of reach from a pole, even on a ladder. I'd have to get on the roof (not a big deal if you grew up cleaning gutters at a house with trees all around it like I did).

[Tell It Right]

One other thing, my math on it paying for itself assumes something else changing over time: energy rates. I assume a 3% inflation rate on power rate, natural gas rate, (and my math on whether or not to get an EV), gasoline price. Even though I no longer have natural gas (because I converted my gas appliances to electric ones), the more natural gas goes up each year the more I save each year by not having to buy natural gas. Also, the more power rates go up the more I save (because I'm saving 52% of my power, according to my solar inverter that tracks how much power I consume and how much power had to be pulled from the grid because my solar system didn't provide it).

Of course power, natural gas, and gasoline prices have all inflated more than 3% lately. If the Dims keep getting their wish and keep inflating them more, my system will pay for itself sooner.