It’s not necessary to use detergents to clean solar panels as Deionised water is sufficient due to it naturally attracting dirt particles. If you choose to use a detergent, it’s generally recommended to use a specialised, mild solution mixed with Deionised water only when you have soiling or stubborn stains that a brush and pure water can’t clean.
Avoid using harsh chemicals or abrasive cleaners, as they can damage the panels or leave residue that may interfere with sunlight absorption. Additionally, using a soft brush preferably water fed for gentle scrubbing can help remove stubborn dirt or grime without scratching the surface of the panels.