These articles may help :-
Here is a video on how to build them: https://www.youtube.com/watch?v=8f10hVL-y0o
Check out mother Earth news.
We had ours, 44 panels, installed professionally about 10 years ago, and we've had negative bills a few times. Our highest bill, one August, pre-panels was $699. (OMG!) Since then, our highest bill has been less than $300. So, whatever you do, go for it!