In mid-June it rained. Hard. In Davis, California. Call it what you’d like: Weird weather, climate change, global warming. One thing’s for sure with the unseasonal rains: Solar panels (and their owners) were smiling on a rainy June day. Now that the rains have subsided and peak-solar generation season is in full swing, our solar panels are collecting dust and pollen and bird droppings. The panels are increasingly frowning.
What’s a solar owner to do?
Solar PV systems require modest maintenance (read: cleaning) to maximize production efficiency. Below are a few tips that will help guide your steps over the life of the system. First, the warnings: exercise great care in accessing the panels. Roof materials get unexpectedly slick. And it’s easy to damage many roofs.
Keep in mind that many owners do nothing for the entire time they own the system. Equipment failures are rare and when they occur, it’s within six months of the installation. Panels are designed to last 25-years or more; inverters last at least 12 years. In short, none of the conditions mentioned below impacts many owners. Still, for those seeking full information, keep reading.
If your home or business is powered by solar, there are three options:
1. Do nothing (i.e., let the rain cleanse your panels).
2. Do it yourself (periodically clean your panels).
3. Hire a cleaning service.
Option #1 (do nothing), obviously, generates the least amount of electricity. Option #3 (hire a professional to clean your panels) optimizes efficiency, but can be quite expensive; the cost of doing so oftentimes exceeds the value of your increased solar generation. (Researchers at UC San Diego concluded, “You definitely wouldn’t get your money back after hiring someone to wash your rooftop panels.”) Herein we focus on the most common alternative: Do it yourself.
As solar panels have no moving parts, the main area of maintenance is to keep them clean. We recommend to check the panels periodically especially during dry periods when precipitating dust occurs with the morning dew. Dirty panels can reduce electricity production as much as 8-12% (results from Department of Energy studies vary). Most dirt can be easily removed with water sprayed from a hose or from rainfall. (Do NOT use high-pressure sprayers as it can damage the seals around the frame.) Important: Wash/spray the panels in the morning to reduce drastic temperature changes. If you cannot ascend your roof, simply spray from the ground and let gravity do the trick … a small wave of water will cleanse most dust. Do not scrub the panels with any harsh materials. If a brush is needed, make sure it has soft bristles, or opt for a common window squeegee. If you notice rapid dirt build up—or bird droppings—then more frequent cleanings are warranted.
Generally, we recommend cleaning your panels every six weeks, commencing in early June (given that our last rains, typically, occur around Picnic Day) and continuing through early September. Hence, 3-4 cleanings every six weeks will suffice.
We monitor the production of 100+ solar systems in our community. Thereby, we can tell when a homeowner has cleaned their panels … solar production increases 5-6%, and then gradually decreases. In addition to our general rule-of-thumb — cleaning every six weeks during peak production season (late May through mid-September — it’s worthy to keep an eye on your web-based monitoring system to gauge if/when your panels would like a bath.
And, of course, feel free to contact us if you have questions.