Does Paying Someone to Clean Home Solar Panels Pay Off?
Summary
On a typical house, the electricity lost to dirt adds up to tens of dollars a year. PVWatts assumes a 2% soiling loss by default. On a 7.7 kW system, the median size for U.S. homes installed in 2025, that is about 199 kWh a year in New York, or about $36 at the June 2026 national average residential price. Cleaning robots appear in IEA PVPS research as a tool for large power plants in dry regions.
Putting a dollar figure on 2%
The PVWatts manual sets 14% as the default for all system losses combined, and its breakdown gives soiling 2% of that. Lawrence Berkeley National Laboratory's 2026 data update puts the median U.S. residential system installed in 2025 at 7.7 kW. We ran that size for a south-facing roof at a 20-degree tilt in three cities and priced the 2% at EIA's June 2026 average residential rate of 18.34 cents per kWh.
| City | Annual output, 7.7 kW | 2% of it | At 18.34¢/kWh |
|---|---|---|---|
| Phoenix | about 13,514 kWh | about 270 kWh | about $50 |
| New York | about 9,941 kWh | about 199 kWh | about $36 |
| Seattle | about 8,378 kWh | about 168 kWh | about $31 |
The 2% is a flat assumption PVWatts applies everywhere, not a measurement from anyone's roof, and the rate is a national average that moves with the state and the rate plan. A quote for one professional cleaning can be set against these yearly amounts to see how many years of lost output it would cost.
Where cleaning robots actually work
A December 2022 report from the IEA's photovoltaic program (IEA PVPS) estimates that soiling cut global annual PV output by at least 3 to 4% in 2018, an economic loss on the order of three to five billion euros. It lists wet and dry brushes, cleaning robots, and electrodynamic cleaning among the methods, and describes the equipment market as moving strongly toward fully robotic dry cleaning, especially where water is scarce and temperatures are high.
The program's summary page frames the problem around large utility-scale plants in arid regions. There, investment in anti-soiling coatings or cleaning robots, and their maintenance, is counted among the costs that soiling creates.
Sources
- NREL — PVWatts Version 5 Manual (NREL/TP-6A20-62641, 2014)
- NLR Developer Network — PVWatts API Version 8 (queried by the editors on September 23, 2026: 1 kW, south-facing, 20° tilt, fixed roof mount, standard module, 14% losses; scaled to 7.7 kW)
- Lawrence Berkeley National Laboratory — U.S. Distributed Solar and Storage 2026 Data Update (August 2026)
- U.S. Energy Information Administration — Electricity Monthly Update, End Use (June 2026 data, released August 26, 2026)
- IEA PVPS — Soiling Losses: Impact on the Performance of Photovoltaic Power Plants (Report T13-21:2022)
- IEA PVPS — Soiling Losses (summary page)
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