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electrical:solar:shading [2020/03/17 16:15] frater_secessus [Partial shading] |
electrical:solar:shading [2020/03/17 16:22] frater_secessus [panel configuration for partial shade] |
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* dedicated controllers for each panel is optimal | * **avoiding shade** is best |
| * a **dedicated controller for each panel** is the next best thing |
* [[electrical:solar:panels|amorphous/thin-film panels]] are less affected by shade | * [[electrical:solar:panels|amorphous/thin-film panels]] are less affected by shade |
* With **PWM controllers, parallel panel configurations typically yield more power** in partial shade than serial. | * With **PWM controllers, parallel panel configurations typically yield more power** in partial shade than serial. |
* With **MPPT controllers** and **low-ish voltage** serial panel configurations (where the total Vmp is <=2x battery bank voltage) it's close but **parallel will probably still yield more**. | * With **MPPT controllers** and **low-ish voltage** serial panel configurations (where the total Vmp is <=2x battery bank voltage) **parallel will probably still yield more**. |
* With **MPPT controllers** and **higher voltage** serial configs (say Vmp is >=3x bank voltage) we see **an increasing advantage of serial panel configs in partial shade**. 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. | |
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| ===== exception: high voltage strings + mppt ===== |
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| 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. |
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===== examples ===== | ===== examples ===== |