With no moving parts, no fuel piping and so on...
ITS TO DO WITH THE PRODUCTION PROCESS
The only way I know of is to invest the money in the stock market. Most savings accounts only pay 3% intrest. While stocks float and if you don't know what you are doing you will never make as much money as you could save on your electric bill. Then the fact that you have to pay the electric bill out of the money. In the end you rented electric and can never get your money back. You can always sell the solar electric system and get your money back plus a profit. Not many people live in the same house even 20 years so it will sell. Toss the coin. It is what ever is best for you.
They are made of costly materials and require expensive manufacturing processes. The market has been limited because people are not catching on very well to the new idea. The more we buy and use solar panels, the more the price will come down.
It's all in the production process that uses materials and processes that are not yet cheap because of the little infrastructure in this field. You can make cheaper solar panels, but it restricts their efficiency, so you get less energy. The reason individuals haven't been catching on to it is because it is not yet entirely cost effective. For a normal 3-person home to be powered completely by solar, depending on many conditions, especially where you live, the payback period is something over 50 years. I live in Boston and for my house to be powered by solar I wouldn't see it making money for over 75 years! What people have to realize is that the point of solar is not to completely power your house cheaply, but to lessen the strain on the electrical grid, and if enough people do this the cost will certainly come down. That and the technology of solar panels has been developing unbelievably fast with all of the green energy buzz going around, so you should see the cost dropping in the next few years as new discoveries are made.
