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About this tool
Plan solar panel cleaning frequency from dust level, tilt and rainfall, with the yield lost and the cost-optimal interval.
A solar panel cleaning planner works out how fast dust eats your generation and how often washing is actually worth paying for. It models soiling as a daily loss rate — typically 0.1% of output per day on wet coastal sites up to about 1% per day near deserts and quarries — scaled for panel tilt and any dust source upwind, then finds the interval where the value of lost units and the cost of washing balance. That optimum follows the square-root rule T = √(2C ÷ (daily generation value × soiling rate)).
Open Solar Panel Cleaning Planner on AltFTool — it loads instantly in your browser.
Add your input to the workspace.
Adjust the options until the result looks right.
Copy or download the output and put it to work.
Compares the rupees lost to dust against the rupees spent on washing, instead of only one.
Rain of 10 mm or more washes panels free, so the planner never recommends an interval longer than that.
A near-flat terrace array fouls about 40% faster than the same panels at 25° because dust never slides off.
It depends far more on dust and rainfall than on any fixed rule, but most Indian rooftop systems land between 3 and 8 paid washes a year. In a semi-arid area losing about 0.55% of output per day, with rain every 45 days and washing costing ₹500, the cost-optimal interval works out to roughly 34 days.
Soiling typically costs 3–10% of annual generation for rooftop systems, and 15–25% at the worst moment in a long dry spell. The loss builds roughly linearly between washes, so a 0.5%/day rate reaches about 15% after a month without rain.
Rain of about 10 mm or more in one event does a reasonable job, which is why a monsoon month usually needs no manual washing at all. Light drizzle is worse than nothing — it wets the dust into a film that dries as a uniform haze across the glass.
Wash early morning or after sunset with soft or deionised water and a soft brush or microfibre head on an extension pole. Never spray cold water on hot glass — the thermal shock can crack a module — and never stand on panels or use detergent, abrasives or a pressure washer. If the array is on a sloped or high roof, hire someone with fall protection rather than doing it yourself.