Updated
Solar panel cleaning in Washington, DC typically costs $15 to $35 per panel, or $150 to $350 for a whole system, per Angi 2026 data. Low-tilt panels on flat rowhouse roofs do not rinse clean in the rain the way steep panels do, so pollen, soot and bird droppings build up into a film that cuts output.
When cleaning actually matters
Rain washes steep panels reasonably well. Flat-roof arrays at low tilt, panels near busy roads and arrays under trees or pigeons collect a film that rain only moves around. The loss shows up as a slow drift down in production.
We check the monitoring first to see whether soiling is really the cause, then clean with soft brushes and deionized water that dries without spots. No pressure washers, no detergents that can void warranties, no walking on the panels.
Pollen and soot film
Spring pollen and city soot settle as a fine film that the rain turns into a muddy layer at the bottom edge of each panel. That edge shading matters more than it looks, because it can affect a whole row of cells. A gentle brush and purified water lift it without scratching the glass or the anti-reflective coating. We clean after the heaviest pollen weeks if you want one visit a year to count, and we note whether nearby trees or traffic make a second visit worthwhile.
Bird droppings
Droppings are worse than dust because they block light completely over a few cells and bake onto the glass in summer heat. A few spots on one panel can pull down a whole string on systems without panel-level electronics. We soften and remove them without scraping, then look under the array for nesting. If birds are living under the panels, the cleaning is a short-term fix, and we will tell you so and price bird proofing separately. Gutters and drains below the array get cleared on the same visit.
Low-tilt panels that never self-rinse
Arrays kept low behind a parapet look tidy from the street, but at shallow tilt the rain sheets slowly and leaves grime along the lower frame. Water can pool against the frame edge, leaving a dirty line that shades the bottom cells. We clean the frame edges as well as the glass, clear debris from the racking and drains, and check that nothing is trapping water against the panels. On these roofs, a yearly cleaning usually earns its keep, and we can time it with the annual inspection to save a trip.
Cleaning a typical DC array
EnergySage data puts the average DC solar system at about 10.61 kW, which on a typical rowhouse is a few dozen panels, so per-panel cleaning prices add up quickly on larger arrays. That is why we check the monitoring before booking a clean: if the system is producing close to what it should, a cleaning can wait. When it is not, we clean, check the array while we are there, and compare the next weeks of production to confirm the cleaning made the difference.
Sources: energysage.com
Signs your panels need a cleaning
A slow production drift
Output sliding month after month without a fault.
A visible film or grime line
Dirt built up along the lower edge of each panel.
Droppings on the glass
Spots that block light over individual cells.
Leaves or debris on the array
Common under nearby trees after storms.
One panel lower than its neighbors
Heavy soiling on a single panel shows in panel-level data.
More than a year since the last cleaning
Especially on low-tilt flat-roof arrays.
How a cleaning visit runs
- 1
You call
Tell us the panel count and the roof type.
- 2
Data check
We look at production to confirm soiling is the cause.
- 3
Rinse
Loose debris is cleared from glass and racking.
- 4
Clean
Soft brushes and purified water on every panel.
- 5
Inspect
We note cracks, loose wiring or nesting.
- 6
Compare
Production after cleaning shows the gain.
What sets the cost of a cleaning
Panel count and access move the price most.
Panel count
Many cleaners price per panel.
Roof access
Steep or high roofs need more setup.
How dirty
Baked-on droppings and heavy film take longer.
Minimum visit
Small systems may hit a minimum charge.
Combined service
Cleaning during an inspection shares the trip.
Planning range: solar panel cleaning runs about $15 to $35 per panel, or $150 to $350 for a system, per Angi 2026 cost data.
Source: angi.com, 2026. A planning range, not a quote; your price follows the site visit.
Hosing them off yourself, or calling us
If you clean them yourself
- Rinse from the ground with a garden hose only
- Clean early or late in the day, never on hot glass
- Skip soap, scrapers and pressure washers
- Never climb onto a roof or walk on panels
When to call us
- Panels you cannot reach safely from the ground
- Baked-on droppings or a heavy film
- Arrays on flat roofs behind a parapet
- When you want the array checked while it is cleaned
Panel cleaning questions
Most need a yearly cleaning at most. Low-tilt, tree-shaded or pigeon-prone arrays may need more.
On steep roofs, partly. On low-tilt flat roofs, rain often leaves a grime line.
Pressure washers, harsh soap and scrapers can. We use soft brushes and purified water.
Not when done with the methods panel makers allow, which is how we clean.
It varies. We compare your production before and after to show the real difference.
Yes, with proper roof safety gear and setup.