This is generally based on the location of the PV project. Generally speaking, wash often in winter and wash less in summer. Frequent maintenance of the solar panels can greatly increase power generation efficiency. In order to ensure normal power generation, solar panels of photovoltaic power stations generally need to be cleaned once or twice a month.
In some places, more dust and less rain, you can consider setting up cleaning system, manual cleaning or automatic cleaning. Rinse with a hose. Be careful not to step on or walk on the solar panel when cleaning. Do not use metal, hard object scrubbing or grinding. Do not spray water at high temperature.
The most direct way to use it without cleaning often is to see if the dust on the battery board is obvious. If it is obvious, it will be cleaned. If it is not obvious, it can be cleaned. Dust and rainfall change every month and every month in every place, so it is not reasonable to give a fixed value.
If conditions permit, you can make a comparison: one panel is often cleaned and one panel is not cleaned. Both panels can be low-powered. You need to clean it if the difference between the two generations exceeds 3%.