It is a common misconception that rainwater will wash your solar panels clean. In reality, relying on rain can actually decrease your system's efficiency over time.
Think of your car: if you leave it out in the rain, it doesn't come back spotless. Instead, it’s often covered in streaks and "muddy" water spots. Solar panels react the same way. Rainwater carries dust and pollutants from the air, which settle on the glass as the water evaporates.
Furthermore, rain is completely ineffective at removing:
- Baked-on bird droppings
- Sticky tree sap and pollen
- Salt spray (common in coastal Perth areas)
For panels with a low tilt, water often pools at the bottom edge, creating a thick "mud-dam" that shades the bottom row of cells and significantly bottlenecks your power production.