While solar panels can continue to work on days when it is not sunny, you should not have them installed if you live in an area that is cloudy most of the time. The amount of energy you save with them will not be worth the amount you paid for them.
Before signing any agreement for installation of solar energy products, get at least three estimates. Once the estimates are in your hand, read each one carefully to ensure that the installation is up to your standards. Each estimate should include a time frame of completion, a list of materials and the estimated amount of labor charged.
Don't look at solar panels as a do it yourself project. You are putting serious funds into these panels, and any mistake can be very costly. Find the right help. Do your research online to come up with the best installers out there near you and interview a few before making any decisions.
Low prices can be very attractive but keep in mind that solar panels and their installation is not cheap. If a vendor has extremely low prices, you are probably getting low quality equipment or even second hand equipment. It is best to invest in quality solar panels and hire a trustworthy contractor to install them.