The 20-25 years seems too long for life expectancy also. You're being overly confident. My experience in designing, selling and installing energy management systems in my own business is that people overestimate the ROI. There are factors people never think about. For example, what about roof replacement during that time and the additional cost if you have panels installed on top of the roof? Someone has to remove the solar panels and re-install when the roof is replaced. Who's going to guarantee the panels work after replacement? What does that do to the roof guarantee? If the solar panel installation company guarantees the roof, will they be there when there is a failure? Most of these firms haven't been in business long and have little likelihood they be around for thirty years. So the guarantee is worthless.
My solar panels are about 7 years old. If they last for 20 years without maintenance costs, I'll be very pleased. However, it's the inverters that tend to be the problem. My inverter had only a 5 year warranty. After 4 years it malfunctioned. I wasn't aware it had malfunctioned until I received the next electricity bill and noticed there were no credits for the feed-into-the-grid of surplus electricity. (I now check my meter box regularly).
The inverter was replaced under warranty, but the new inverter gave up the ghost about 2 years later. There was a lot of confusion about the warranty period because the initial 5-year warranty had expired. However, I was pleased that the Australian manufacturer of the replacement inverter (the first one was Chinese) honoured their 5 year warranty and repaired it at no charge.
The best inverters, probably made in Germany, tend to have a 10 year warranty.
However, the main problem with renewable energy is its reliability. Imagine whole cities with their many suburbs relying upon solar power. The roof of each house is decked with solar panels. The surplus electricity generated from thousands of roofs recharges electric vehicles and supplies various industrial needs.
Isn't that wonderful! Thank God for those AGW alarmists. Oops! What happens when a devastating storm occurs? A hurricane rips off most of those solar panels, and huge areas are without power, (for how long?) Imagine the reconstruction costs and the huge delay before power is restored.
I recall a few years ago reading about the devastating effects of Hurricanes Katrina and Sandy in the US. I'm sure there would have been a lot of news reports blaming human emissions of CO2 for the severity of these storms.
However, some time later I recall reading an interesting article in Scientific American about a previous storm which occurred in December 1861, which appears to have been much worse than Katrina or Sandy.
We tend to judge the severity of a storm by the number of deaths that result, and the cost of the damage, but that's purely emotional and tends to create the false impression that storms are becoming more severe, as a result of rising CO2 levels. It's very doubtful that they are becoming more extreme, globally, but the damage to life and property is more extreme due to increased population and development.
What I also find interesting in the following article, is the narrative that the local Indians were able to recognise the signs of an impending storm and flood and quickly moved out of the area. The Western immigrants were stuck; too proud to take the advice of the Indians.
It is reasonable to presume that the Indians were able to recognise the signs of an impending storm because such storms had occurred in the past and descriptions of the circumstances were passed down from father to son. I can't see any connection with CO2 emissions here.
The great danger of CO2 alarmism is that people will become complacent about the dangers of extreme weather events when alternative energy supplies are in place. They will tend to think, "We've behaved responsibly and have accepted the advice of climate scientists and spent huge sums of money on solar panels and windmills, so now everything should be all right. No need to worry about extreme weather events." Dear me!
https://www.scientificamerican.com/article/atmospheric-rivers-california-megaflood-lessons-from-forgotten-catastrophe/