Solar Panels

The product warranty comes from the solar panel manufacturer and covers your panel for manufacturing defects, premature wear and tear. Your panels could be up on your roof for a very long time so the longer your warranty, the longer you are guaranteed to be saving on electricity costs.

The performance warranty comes from the solar panel manufacturer. It guarantees a minimum output from the panel over time, typically at 10 and 25 years. Solar panels do degrade over time, so this is a really good indicator of how the manufacturer expects the panel to perform in the long run. A panel with an 80% performance warranty at 25 years will produce 10% less than the same panel with a 90% performance warranty for the 25th year of the panels operating.

The performance of solar panels actually decreases as the temperature of the panel increases. As the panels are on your roof in direct sunlight, they will be much hotter than the air temperature. The temperature coefficient indicates the percentage decrease in output for every degree above 25. For example if the panels have a temperature coefficient of -0.39% and are at 40 degrees, then the reduction in output will be 15 x 0.39 = 5.8, meaning the panel output will decrease by 5.8%.