How many panels will I need?
Here's a simplified worksheet to help you get a general idea of the number of panels you will need. Be sure to crosscheck the number of panels with the California EPBB calculator for the most accurate results. You will need to get the panel CEC-AC rating here by downloading the PV Module List - Full Data. This is a very large list, and takes a few minutes to download. If you are in a hurry, you could assume the CEC-AC rating is about 86% of the panel watt size; e.g., a 250 watt panel is about 215 watts CEC-AC. (CEC is abbrev for Calif Energy Commission). In the chart below, the 4.6 hours is the approximate hours of daylight based on the CA EPBB calculator. In can vary, but that's a good rule of thumb when you are estimating without getting into specifics. I can help you with that, if you contact me. You can also get it by using the calculator: You can find the EPBB calculator by clicking here.
How much should they cost?
The State of California has listed the average pricing for solar panel installations. It is a charted amount. When you go to the page to see this amount, you will need to enter in PG&E and Residential for the chart to correctly display the information you are looking to find. Below is the extracted chart for the information as of May 10, 2018:
Therefore, if you were to use 300 watt panels, and you needed 30 panels, your cost would average 300 x 30 x $4.70, or an average price of $42,300. There would be a tax credit possible that would reduce the cost by 30% to $29,610. If 30 panels reduced your power from PG&E to zero, your energy costs would end after you paid off the $29,610.
My price would be much lower.
My price would be much lower.