There are some very heavily advertised guides for sale on the Internet in the $50 range that promise that you can make PV panels that will provide “80%” of your homes power for a couple hundred dollars.
You can be sure that anyone making these kinds of claims is a scammer — don’t waste your money. You will find plenty of free and honest information below for reputable sources. Go Green Electricity An easy calculator you can use to find out how much power you will get from a PV installation in your area. Also very helpful for panel aiming studies. It calculates PV system performance based on hour by hour records for sun in your area. Version 1 is very easy to use, and works worldwide. This appears to be a good tool for estimating the economic return for installing a PV system for your area. Allows you to change location, size & cost of array, and financing. Shows details on power output, cost savings, and return on your investment. While it is offered by a company selling PV equipment, it does not appear (to me) to be overly optimistic on power generated.