Solar panels are designed to sit outside for 25+ years, and in the process they may get quite dirty. We usually get asked “how do I clean my solar panels?”, but the first question you should ask is “do I need to clean my solar panels?”
For most solar homeowners, especially those living in Virginia (that’s where we operate), cleaning is not necessary. That said, dirt and debris will lower your systems performance, so if you want to get the absolute most out of your system, read on!
Safety first
Before you start cleaning your solar panels, first make sure you can do it safely. We like climbing on roofs, but doing it safely is difficult. If you can’t safely access your solar panels, getting an extra smidge of efficiency isn’t worth getting injured over! The efficiency gains from cleaning panels is generally in the 1-4% range, depending on how soiled they are. Make sure it’s worth it, and that you can do it safely before risking life & limb.
Note: I can’t stress enough how much we don’t recommend climbing on a roof. Standing on the ground & setting the garden hose at the roof should get the job done.
When to clean solar panels
In most climates (Virginia included) rain will do most of the cleaning for you, but if you are going to clean your panels anyways, the best times to clean are these:
- Late Spring: After the pollen has settled, you’ll probably see a familar layer of yellow dust on all your panels. Once the trees stop dropping pollen, give your panels a spray.
- Late Fall: Once the leaves have settled, there may be a few stuck on your solar array.
- Signs Your Panels Need Cleaning: Look for visible dirt, dust, bird droppings, or leaves. If you notice a significant drop in energy production across all your panels, it might be time to clean your panels.
- Dry spells: If there are prolonged dry-spells, panels can collect dust, especially if you live on or near a gravel road. If you live in California or arid areas with lots of dust, cleaning can help bring back lost performance.
How to protect your solar panels while cleaning
Solar panels are generally pretty tough, but there are a few things you should be aware of to ensure that you do not damage them while cleaning:
- Solar panels have anti-reflective coatings on the glass. Make sure you do not clean with chemicals, as it could damage the coatings, and decrease the efficiency & longevity of your panels
- The tempered glass front is joined to the frame with adhesives. Make sure not to use a high-pressure sprayer, as high pressure could break the seal between the frame and the glass. A compromised seal, due to chemical or physical damage can greatly decrease the life of your solar panels
- Don’t walk on your solar panels. While you probably won’t shatter your panels, excessive flexion of the panels can cause micro-cracks in the cells, leading to increased degredation.
How to clean solar panels
Use a garden hose with a gentle stream of water to rinse off the panels. Soaking soiled areas, and then spraying them off later can help loosen some of the dirt. If you need to scrub off bird poop or other tough spots, use a very soft brush that won’t scratch the glass or coatings.
Never use chemicals to clean your solar panels.
Other solar maintenance tips
Here are a few other tips to get the most out of your solar system:
- Regular Inspection: Periodically inspect your panels for dirt, damage, or shading issues caused by growing trees.
- Light Cleaning: Perform light cleaning as needed, especially after periods of heavy pollen, dust storms, or bird activity.
- Keep Surrounding Areas Clean: Trim nearby trees and clean gutters to minimize debris falling onto your panels.
- Monitor your Solar System Regularly: It’s easy to lose track over the years, but setting a monthly or quarterly reminder to check your solar monitoring software can ensure everything is working properly. If you have a system with a string inverter, this is especially important, as older inverters have higher failure rates, and will stop the entire system’s production if they fail.
