Can I combine multiple solar panels with one DC breaker?

DC Breaker Sizing Basics

When sizing a DC breaker for a solar panel array, the key consideration is the total DC power output of the combined panels. Most solar panels have a maximum power rating (Pmax) in watts, typically ranging from 250 to 400 watts per panel. To determine the required DC breaker rating, add the Pmax ratings of all panels connected in series or parallel configurations.

Series and Parallel Configurations

In a series configuration, the voltage of each panel adds up, while the current remains the same. In a parallel configuration, the voltage remains the same, while the current adds up. When sizing a DC breaker for a series configuration, the breaker rating should match the total voltage of the panels. For example, if you have two 12-volt panels in series, the breaker rating should be 24 volts or higher. In a parallel configuration, the breaker rating should match the total current of the panels. For example, if you have two 10-amp panels in parallel, the breaker rating should be 20 amps or higher.

Sizing Example

Suppose you have three 300-watt solar panels connected in a parallel configuration, with each panel producing 10 amps of current. The total current of the array is 30 amps, and the total DC power output is 900 watts (3 x 300 watts). To determine the required DC breaker rating, you would need to select a breaker that can safely handle 30 amps of current and 900 watts of power. A 30-amp DC breaker with a 250-volt rating or higher would be suitable for this application.