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electrical:solar:shading [2020/10/11 19:48] 127.0.0.1 external edit |
electrical:solar:shading [2022/08/06 15:18] (current) frater_secessus [Partial shading] |
====== Partial shading ====== | ====== Partial shading ====== |
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Partial shading can have surprisingly dramatic effects on [[electrical:solar:output|panel output]]. The weirdest part is that //partial// shading can have more devastating effects on output than //full shading// like heavy overcast or evenly shaded forest canopies. | Partial shading can have surprisingly dramatic effects on [[electrical:solar:output|panel output]]. Perhaps counterintuivitely, //partial// shading can have more devastating effects on output than //full shading// like heavy overcast or evenly shaded forest canopies. |
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===== reminder: how panels work ===== | ===== reminder: how panels work ===== |
There is another approach, which is to **bring the shaded cells/strings back online by bringing the rest of the panel down to their level**. It sounds counterproductive, but with MPPT controllers and in some higher-voltage series configurations (say Vmp is >=3x bank voltage) it works. | There is another approach, which is to **bring the shaded cells/strings back online by bringing the rest of the panel down to their level**. It sounds counterproductive, but with MPPT controllers and in some higher-voltage series configurations (say Vmp is >=3x bank voltage) it works. |
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This occurs because the MPPT has a broader range of voltages to sweep and can find [[https://www.sciencedirect.com/science/article/abs/pii/S0960148113006952|other power peaks]] (panel voltages) that are **low enough to bring the shaded cells back online** but still **high enough to charge the battery bank**. It's not reality, but we can think of it as MPPT evenly "shading" the entire panel voltage-wise in order to get max juice from it in partial shade conditions. | This occurs because the MPPT has a broader range of voltages to sweep and can find [[https://www.sciencedirect.com/science/article/abs/pii/S0960148113006952|other power peaks]] (panel voltages) that are **low enough to bring the shaded cells back online** but still **high enough to charge the battery bank**. It's not reality, but we can think of it as MPPT evenly "shading" the entire panel voltage-wise in order to get max juice from it in partial shade conditions.((https://diysolarforum.com/threads/mppt-sizing.17947/post-208104)) |
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===== examples ===== | ===== examples ===== |
* [[https://www.youtube.com/watch?v=QzzB1i1w_kM|altE video on partial shading]] | * [[https://www.youtube.com/watch?v=QzzB1i1w_kM|altE video on partial shading]] |
* [[https://www.youtube.com/watch?v=ofo1HQyGG8s|wiring shaded panels]] | * [[https://www.youtube.com/watch?v=ofo1HQyGG8s|wiring shaded panels]] |
| * [[https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28152689.cfm|Solar Panel Shadows and Bypass Diodes]] |