# What is the best way to configure 3 strings of 12 panels to combiner box? Keep all leads short as possible or group panels to mim. shade?

Here are the options I am considering:

Option 1 - Minimize all leads both positive and negative to combiner box.

Option 2 - Minimize only the positive leads

Option 3 - Organize panels into groups so that morning sun shade moves across the the array in such a way that power is maximized.

Submitted

10 years 6 months ago

Support topics

Installation

System sizing

Wiring and circuits

Support tags

solar panel

combiner box

configuration

## Comments

Impedance = capacitive reactance + inductive reactance + resistance.

In a DC circuit impedance is equal to resistance.

In an AC circuit (at 60 hertz) there is not much capacitive reactance, or even inductive reactance.

The DC PV circuit consists of both + and - wires (plus whatever is in the circuit).

Therefore all wires must be shortened to reduce voltage drop.

The Electrical Code limits voltage drop in any one circuit to 3%.

That is intolerable in PV systems. Limit voltage drop to 1% or less by using larger wire sizes.

Remember, you buy the wire once, but the power loss goes on forever.

On another subject, after researching how current flows in a DC system, I realized that current flows negative to positive which is opposite of the "convention" positive to negative. It would had been to my advantage to shorten ALL wires both positive and negative rather than shorten just the positive. You're absolutely right on the advice to shorten all wires as much as possible on a DC system. Just wondering if this is the reason some systems have positive ground.