Cleaning with cold water under direct heat on a sunny day can cause thermal shock (sudden temperature changes that stress the glass and risk it shattering). Start with a visual inspection: Look for cracks, loose cabling, or signs of water damage before cleaning. However, water evaporates quickly on hot surfaces, leaving behind mineral. Water Spots: When tap water evaporates from the solar panel's surface, it can leave behind water spots, which can also block sunlight. Potential for Damage: The use of hard water for cleaning can lead to the creation of hotspots on the panels, which can damage the solar cells. The primary reason for cleaning on sunny days relates to precipitation's role in removing grime; however, sunlight. If you still prefer DIY, the best way to clean solar panels is to stick to using low-pressure water, a soft nylon-bristle brush on a long handle, and a mild, non-abrasive detergent when the panels are cool in the morning or evening. When contaminants block this surface, less sunlight reaches the cells, reducing energy production.
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