diy solar

diy solar

Do older Evergreen Solar panels have bypass diodes?

creggar

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Aug 15, 2023
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Mossyrock WA
I've got the evergreensolar ES-E-220-fc3 panels. I think I got them around the time Evergreen was going bankrupt, maybe 2011. Anyway, all I see in the junction box is molded silicone/resin. And using a multimeter to check for diodes doesn't give me an open reading in either direction. So, does anyone know if I'm supposed to have bypass diodes in these panels? thanks
 
While not for the UL panel, I expect it applies:

1692122050794.png

When testing for short circuit current, if you blackout shade a single cell, Isc should drop to zero or near 0 amps if no bypass diodes. If you can fully blackout shade any cell in the one to two of the 1/3rd panel zones below and still get the same Isc as the unshaded panel, the diodes are working.

1692122237445.png
 
Bypass diodes play an important role in photovoltaic modules. The following are the main functions of the bypass diode:

Countercurrent prevention: Bypass diodes allow current to pass in one direction while blocking the flow of reverse current. This is important to prevent the backflow of photovoltaic modules at night or in low-light conditions. Countercurrent may cause energy loss or damage to components.

Component protection: Bypass diodes can also protect photovoltaic modules from damage or overheating. When components operate under partial shadow or fault conditions, some units may generate reverse currents. Bypass diodes can divert these reverse currents around the affected unit, preventing it from being damaged.

Performance optimization: By using bypass diodes, the overall efficiency of the photovoltaic module can be maximized. It reduces energy loss due to local shadows, dust or other failures, ensuring that light energy is converted to electricity with maximum efficiency.

In short, bypass diodes play a key role in preventing countercurrent, protecting components, and optimizing performance in photovoltaic modules. They ensure that photovoltaic systems work efficiently and reliably and provide maximum energy output.
You can refer to the above theoretical knowledge to understand whether you need to bypass diodes
 
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