Solar panels are incredibly efficient at converting sunlight into electricity, but they’re also very sensitive to shading. Even a small amount of shade can have a drastic impact on their power output. As we transition into late autumn, with the sun lower in the sky than in June, shading on panels becomes even more severe, further reducing their performance.
Here’s a breakdown of how shading affects solar production, based on recent tests:
- Full Sun Exposure: In optimal conditions with full sunlight, a solar panel can generate its maximum power output. For example, in our test, a 290W panel produced roughly 295W. This is the benchmark for understanding how shading impacts performance.
- Partial Cell Shading: When half of a single cell is shaded, the power output drops significantly. In our test, shading just half of one cell reduced the panel's output from around 295W to 190W—about a one-third reduction. This drastic drop occurs because shading one cell can disrupt the entire series of cells in a panel.
- Row Shading: When one row of cells is fully shaded, the panel’s power output drops to zero. This happens due to how solar cells are wired within the panel; shading one row interrupts the entire series circuit, cutting off power production altogether.
Why Does Shading Have Such a Big Impact?
Each cell in a solar panel is part of a series circuit, meaning the current flowing through each cell is interdependent. When one cell is shaded, it limits the current for the entire row, effectively reducing the panel’s output. This characteristic, known as the “Christmas light effect,” can completely stop power production if enough shading is present, as shown in our test.
In summary, even minor shading, such as a nearby branch or a rooftop obstruction, can drastically reduce solar panel efficiency. It’s essential to consider shading when installing solar panels.
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