Quick Answer
Shading affects solar panels wired in series more significantly than those wired in parallel, as series-wired panels will produce significantly reduced output when one panel is shaded, while parallel-wired panels will maintain most of their output.
Shading Effects on Series-Wired Panels
When solar panels are wired in series, the output voltage is the sum of the individual panel voltages, but the current is the same as that of a single panel. Shading one panel in a series-wired array will significantly reduce the overall output voltage and current, as the shaded panel will have a much lower voltage than the other panels. For example, in a 3-panel series-wired array, if one panel is shaded and produces only 10% of its rated voltage, the entire array will produce only 10% of its rated voltage.
Shading Effects on Parallel-Wired Panels
In contrast, solar panels wired in parallel will maintain most of their output when one panel is shaded. The current from each panel is added together, and the voltage remains the same as that of a single panel. For example, in a 3-panel parallel-wired array, if one panel is shaded and produces only 10% of its rated current, the other two panels will still produce their full-rated current, resulting in a total array current of 9 times the rated current of a single panel.
Calculating the Impact of Shading on Array Output
To determine the impact of shading on a solar array, you can use the following formula: Array output = (1 - (shaded area as a percentage of total area)) * (number of shaded panels / total number of panels). For example, if a 3-panel series-wired array has 20% of its total area shaded and one panel is completely shaded, the array output would be reduced to 60% of its rated output.
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