How to Compare Solar Panels for Homeowners

A photovoltaic cell's efficinecy is measured in factory and real world conditions.

When comparing photovoltaic (PT) solar panels for home use, there are a few important statistics to look for at the dealers: the STC versus PTC rating, the square footage of the panel, the ratio between PTC and square footage, the warranty offered, the price, and the reliability of the dealer. There are dozens of solar panel models sold in the USA. Cutting through the chaff of statistics and deals will help you pick the best solar panel for you.

Instructions

Instructions

1. Ask for the PV USA Test Conditions (PTC) specs on the solar panel you're interested in. The dealer may list the STC, which stands for Factory Standard Test Conditions, but this doesn't reflect the real-world efficiency of the solar panel. An excellent PTC will be above 180, a good one above 177. Anything below these numbers is suspect.

2. Compare the PTC to the square footage of the panel. An excellent PTC to square footage ratio is above 14. The ratio is important because a very large panel may have a higher PTC rating, but only because it's so large. The ratio helps compare panels of different sizes.

3. Choose what the energy of the solar panels will be used for--heating pools, hot water, or home electrical use. Different systems of electrical use call for different panels and installation procedures, which lead to different prices.

4. Know how much on your electric bill you want offset by solar panels. Knowing this percentage helps you find the right installation package, which determines how many panels you actually purchase.

5. Compare the pricing of individual solar panel packages. A solar panel will cost about 150 dollars and up, depending on the quality and size. If you aren't installing them yourself, consider the different prices of installations that are offered by the solar panel dealer. The panels, however, can be installed by a company other than the manufacturer of the panel.

6. Look at the pricing of accessories in the solar panel system that are necessary to use solar panels, such as batteries, mounts, and monitoring equipment.

References

• Value Solar: STC rating versus PTC rating
• SRoeCo Solar: Most Efficient Solar Panels