Getting solar? Clean the roof first.
Why to soft wash the roof before solar panels go on: algae keeps growing under the array, cleaning later means pulling panels, and a clean roof runs cooler and is easier to inspect. · 4 minute read
Why timing matters
Once a solar array is mounted, a large part of your roof is under panels for the next 20 to 25 years. Algae and black streaks do not stop growing because they are in the shade. In fact shade and trapped moisture help them. Cleaning the roof under an installed array means paying to detach the panels, clean, and reset them. Cleaning before install costs a normal roof wash.
What happens if you skip it
The panels cover the middle of the roof, but the streaks keep spreading around the edges and down the slopes you can see from the street. You end up with a stained roof framed around new panels, and an HOA letter that is harder and more expensive to fix.
A clean roof runs cooler
Black algae turns a light gray or tan roof dark, and darker surfaces absorb more sun. That heat moves into the attic, where your AC has to fight it. Research on roofing materials by Lawrence Berkeley National Laboratory has found that soiling and biological growth lower a roof's solar reflectance, and that cleaning restores much of it. How much it changes your bill depends on your roof color, insulation and AC, so we will not promise a number. But a clean roof is not working against your AC, or against the panels you are paying for.
Inspect before you mount
A soft wash shows the roof as it really is. Damaged shingles, lifted tabs and cracked tiles are easy to spot on a clean roof and easy to miss under algae. Fixing them before the array goes on is far cheaper than after. We photograph anything we notice and send it to you and your installer.
How to schedule it
Book the roof wash anywhere from a few days to a few weeks before your install date. We use a low pressure soft wash on shingle, tile and metal, never a pressure washer, and the roof usually dries the same day. You get before and after photos you can forward to your installer. Already have panels? We clean installed arrays with soft brushes and purified water. See solar panel cleaning.
Questions people ask about this.
Will my solar installer clean the roof?
Most do not. Installers mount panels; roof cleaning is a separate trade. Ask yours, and if they do not, book it before install day.
Does roof cleaning affect my roof or solar warranty?
A low pressure soft wash is the method shingle manufacturers recommend. High pressure washing is what can void a shingle warranty, and we never use it on roofs or panels.
How long does a clean roof stay clean?
In Central Florida a soft wash typically keeps a roof clean for 18 to 24 months. Panels then shade part of the roof, so the edges are what to watch.
Clean roof, then solar.
Text a photo of your roof with your address and your install date, and we will quote it and schedule around your installer.