This shows you the differences between two versions of the page.
Both sides previous revision Previous revision Next revision | Previous revision Next revision Both sides next revision | ||
electrical:solar:shading [2020/02/07 06:36] frater_secessus [examples] |
electrical:solar:shading [2020/10/11 19:48] 127.0.0.1 external edit |
||
---|---|---|---|
Line 1: | Line 1: | ||
+ | Words of Wisdom: | ||
+ | |||
====== Partial shading ====== | ====== Partial shading ====== | ||
- | Partial shading can have surprisingly dramatic effects on 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: |
+ | ===== reminder: | ||
+ | **Before we begin:** solar panels are " | ||
+ | Partial shading in this context means: | ||
+ | * light is falling on the panel | ||
+ | * but not evenly on the panel -- it is different on some cells | ||
+ | To prevent power from rushing into the shaded string and overheating them, panels have bypass diodes between the strings. | ||
- | It works this way: | ||
- | |||
- | - partial shade causes //voltage differences// | ||
- | - electricity flows from higher-voltage areas to lower-voltage ones, so voltage differences would cause power to rush into the lower-voltage (shaded) cells | ||
- | - overheating the shaded cell and possibly damaging it | ||
- | |||
- | To prevent damage panel manufacturer' | ||
===== panel configuration for partial shade ===== | ===== panel configuration for partial shade ===== | ||
Line 21: | Line 22: | ||
- | * With **PWM controllers, | + | * **avoiding shade** is best |
- | * With **MPPT controllers** and **low-ish voltage** serial panel configurations (where the total Vmp is <=2x battery bank voltage) | + | * a **dedicated controller for each panel** is the next best thing |
- | * With **MPPT controllers** and **higher voltage** serial configs | + | * [[electrical: |
+ | * With **PWM controllers, | ||
+ | * 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**. | ||
+ | |||
+ | |||
+ | |||
+ | ===== exception: | ||
+ | |||
+ | There is another approach, which is to **bring the shaded cells/ | ||
+ | |||
+ | This occurs because the MPPT has a broader range of voltages to sweep and can find [[https:// | ||
===== examples ===== | ===== examples ===== |