What’s the Recommended Distance from Panels to Combiner Box?

Combiner Box Placement

When designing a solar panel system with parallel wiring, it’s essential to place the combiner box in a location that is easy to access, yet protected from the elements. Typically, this means installing the combiner box at a height of around 6-8 feet off the ground, with a slight overhang to prevent water from accumulating. The distance from the panels to the combiner box is often dictated by the wire size and the desired voltage drop. As a general rule, a 10-gauge wire can handle up to 100 feet of run without excessive voltage drop, but this distance can be increased with larger wire sizes or by using voltage drop calculators to determine the optimal distance.

Wire Sizing and Voltage Drop

When sizing the wire for the run from the panels to the combiner box, it’s crucial to consider the voltage drop and the wire’s current-carrying capacity. A good rule of thumb is to use a wire size that can handle at least 125% of the system’s maximum current. For example, if the system’s maximum current is 20 amps, use a 10-gauge wire, which can handle up to 25 amps. Additionally, consider using wire with a UV-resistant jacket to protect it from the sun’s rays and extend its lifespan.