with no maintenance to speak of. I may have hosed the dust off two or three times in that 20 years, otherwise they only get washed when it rains. They have been sitting out in the sun's rays, wind, rain, moisture, corrosion, dust and bird droppings all that time. Last year they survived a hail storm that was so bad everyone in my neighborhood, including me, had our roofs replaced.

They are still putting out the current they did 20+ years ago. Old Solarex SX-60 panels.

Any man made machinery will eventually have breakdowns, and he has listed many that may possibly happen to and PV solar installation. And poor design, manufacturing, installation or monitoring and maintenance will make it worse. (I know, I had an 1974 Chevy Vega.) Hail, lightning, hurricanes and tornadoes as well as damage from critters (birds, rodents) do happen, but those kinds of damages are what insurance is for. It is why my house is insured.

But a quality install of a PV solar equipment will have the lowest failure rate over 20 years of any power generating system I can think of. Do you think that a coal fired steam generator will run 20 or 30 years without downtime or repairs? Prieto is correct that all costs current and future must be fairly accounted for, but this should apply to all possible electrical energy sources.

And his "Energy Return on Investment" has it place, but how about just a real Money return on investment. In my personal case I installed 10kwdc of solar panes just under two years ago, and have been monitoring them closely.

They have put out 12 thousand Kilowatt-Hours (AC metered) of real electricity each year. At my current rate from AEP that is $1,440.00 worth of electricity per year. I spent about $15,000 on the equipment and installed it myself so it was a very low price. But without any other subsidies, and a super simple return calculation. I will pay for the system in 10.4 years. If it does last 20 years, the next 10 years will be "free" energy to me.

I had been paying AEP about 2 thousand dollars a year for energy on my all electric home. I would be paying this out every year for the rest of my life, certainly over the next 20 years if I live this long.

So the real question is can I pay less than this fixed situation of buying energy from AEP.

And of course the actual cost analysis is a bit more complicated as the cost per KWH from AEP will keep rising, there are interest costs in borrowing the money, There will be some maintenance costs, and other subsidies do apply at the whim of politicians.

Again in my case I took the income tax credit which lowered my cost from 15 thousand to about 10 thousand up front. The energy my system makes "creates" about 12 SREC s (Solar Renewable Energy credit) per year. Before Governor Kasich and the Repubs got hold of them they were worth over $300 each, or $3,600 per year in SREC production. At that rate, my system would have been paid for in less than 3 years! (and then made me a profit after that). But SRECS have fallen to about $30 each (90%), and only worth about $360 per year. The SRECS income and interest costs are probably about a wash now.

So ignoring interest charges and AEP increases, my system will pay for itself in less than 6 years!
Instead of paying AEP $40,000 total over the next 20 years, I will be paying them about 10,000 for the extra power I needed, and the 10,000 I paid after tax incentives.
I will pay about half in total of what I would have had to pay to AEP anyway. I will be happy to keep a thousand a year in my pocket instead of AEP's.

This is why the big power utilities are coming after rooftop solar tooth and nail.