My panels look dirty, do I need to clean them?

A common question people ask is do they need to clean their solar panels? The answer is generally no. Lets look into the details.

What you should know before getting your solar panels cleaned.

Solar panel manufacturers have specific instructions for cleaning and maintenance, it’s outlined in the installation manual and varies per manufacturer. Since we install Maxeon Solar panels, lets take a look at what they say.

6.0 Maintenance and Cleaning

Trained Maxeon dealer or trained Maxeon support personnel should inspect all modules annually for safe electrical connections, sound mechanical connections, and freedom from corrosion. Periodic cleaning of module glass has resulted in improved performance levels, especially in regions with low levels of annual precipitation; therefore Maxeon recommends periodic cleaning of the modules. To clean a module, wash its glass surface with potable, non-heated water. Normal water pressure is adequate when cleaning the AR glass. Some fingerprints, stains, or accumulations of dirt on the glass may be removed with over-the-counter glass cleaners (such as Windex® or equivalent), or with a 3% soap-and-water solution. For smaller systems, wet the module glass with the solution, let it stand for five minutes, and then wet them again and use a soft sponge or seamless cloth to wipe the glass surface in a circular motion. For large systems, wet the modules with the cleaning solution, let them stand for five minutes, and then rinse them with high-pressure water or a soft squeegee. Do not use harsh industrial-strength cleaning materials such as scouring powder, steel wool, scrapers, blades, or other sharp instruments to clean the module glass. Use of such materials will void the product warranty.

Many companies will use harsh chemicals, stiff bristle scrub brushes, squeegees, and high-pressure water to clean solar panels. In most cases, this could void your solar panel’s warranty. So if you hire someone to clean your solar panels, or clean them yourselves. You need to be aware of this.

Let’s get cleaning

We have a Customer who’s neighborhood has a major pigeon issue. All the solar panel installations in the neighborhood are quite filthy with pigeon droppings. Despite the pigeon netting we installed when we put the solar in the pigeons still found a way under the array, so we went back to add more netting, spikes, and a reflective spinner to deter the pigeons.

While there we cleaned the panels and we’ll compare the before and after to see if cleaning your solar panels is worth the cost.

These photos show how dirty the solar panels were before cleaning. They have az lot of pigeon droppings on them.

The solar panels look very dirty, so we’d expect that they aren’t going to perform very well. Since these solar panels are top of the line Maxeon Solar panels they still perform exceptionally well with shading and soiling.

Lets look at the solar production from the system the day before cleaning. Since we installed Enphase Micro inverters on each panel, we can see exactly how much power each panel produced. For the day, it produced 77kWh.

View of the electrical production per panel and micro inverter on the day before cleaning.

Photo of solar panels after cleaning.

After the cleaning, they look much better, but how does the electrical production compare?

This was the solar production on the day after cleaning with the same weather conditions. It only produced 0.5 kwh more.

After cleaning, the energy produced only increased by 0.5 kWh or 0.65%. With the cost of solar panel cleaning being roughly $300, if we assume cleaning adds 0.5 kwh per day for 365 days, that would only be an extra 182.5 kWh for the year. Assuming a grid electricity price of 13 cents per kwh, that’s only an improvement of $23.72.

So even though it doesn’t rain much here in Las Vegas, we still recommend most people don’t need, and won’t benefit from paying for cleaning their solar panels.