FAQ: What is inside the junction box on the back side of the solar panel?

Answer: The junction box contains terminal wires (+ pole), (- minus) and also by-pass diodes.

The purpose of bypass diodes is to shunt the current around a shaded, weak or damaged panel. Otherwise there is the risk that full current from the rest of the panels will pass through the shaded panel and cause overheating damage. In this case the bypass diodes conducts, thereby allowing the current from the good solar cells to flow in the external circuit rather than forward biasing each good cell.

Larger panels have more diodes to provide as much as possible power, even if part of panels is damaged or shaded.

Example:

Schutten panel 250Wp Poly has 6 diodes. Two over each section see picture above.

Schutten panel 140Wp Poly has 2 diodes. One over each section.

All Schutten panels have by-pass diodes to avoid any damage.