Quick Answer
Solar array DC breakers should be sized according to the inverter's DC input current rating, which is usually provided by the manufacturer in amps. A general rule of thumb is to round up to the nearest 10A increment when sizing the breaker. This ensures the breaker can handle the full DC output current from the solar array.
Sizing Breaker for Inverter DC Input Current
When sizing solar array DC breakers, the key factor is the inverter’s DC input current rating. This value can be found in the inverter’s specifications or datasheet, usually expressed in amps. As a general guideline, it’s recommended to round up to the nearest 10A increment when sizing the breaker. For example, if the inverter’s DC input current rating is 15.4A, the breaker should be sized to 20A.
Consideration for Higher DC System Voltages
For higher DC system voltages, such as 600V or 1200V, the inverter’s DC input current rating may be lower than the system’s total DC output current. In such cases, it’s essential to calculate the total DC output current from the solar array and ensure the breaker can handle this value. A common approach is to use a DC power calculator or consult the inverter manufacturer’s guidelines to determine the required breaker size.
Additional Considerations for System Design
In addition to sizing the breaker according to the inverter’s DC input current rating, other factors should be considered in the system design. These include the type of inverter, number of panels, and the system’s total DC output voltage and current. A well-designed system will ensure safe and efficient operation, and the selected breaker will be sufficient to protect the system from overcurrent conditions.
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