5 Questions to Ask Before Purchasing a Solar Electric System

This is an edited excerpt of an article originally posted on AOL Real Estate written by Audrey Tempelsman. Audrey asked me to help her on an article you can read in full here.

There are a nerve-wracking number of solar manufacturers and installers out there, so I caught up with Shawn Roe of SRoeCo Solar, a solar advice service, and asked him to share five questions that all consumers should ask before purchasing a system. I hope you’ll find his insight as helpful as I did:

1. “How many systems has your company installed?”
Due to the recent spike in solar panel installations, and the decrease in other construction-related businesses, many roofers, fencers, and builders are attempting to start solar installation companies with no solar experience and without proper solar installation knowledge. Look for a reputable installer with at least 50 installations and a few references.

Solar Efficiency Losses Over Time

How much do solar panels decrease over time? The solar industry standard is a conservative estimate of 3% in the first year, and less than 1% per year after that. However, solar panel manufacturers are starting to realize that this is too conservative, and they are beginning to warranty their panels to more realistic degradation rates.

There are three points I want to make.

Use the solar panel’s warranty to compare output loss over time because that is the only output you are guaranteed.
Realistically expect less than a 3% decrease in output the first year, and about .5% decrease per year after that for most panels.
One solar panel from 1979 was tested in 2010 (after 30 years) and its output was better than the original factory specs.