Quick Answer
You should fuse each string in your parallel solar setup to prevent damage from short circuits, overcurrent conditions, and other safety risks.
Fusing Requirements for Parallel Strings
When wiring solar panels in parallel, it’s essential to fuse each string to protect it from potential overcurrent conditions. This is because the total current drawn from the panels in a parallel setup is the sum of the individual currents, and if one string experiences a fault, it could cause the entire system to overheat or fail.
Fusing Techniques and Devices
You can use either a fuse or a circuit breaker to protect each string. However, fuses are generally more suitable for large solar systems, as they provide a more precise level of protection. The American Society for Testing and Materials (ASTM) recommends using fuses rated at 150% of the string’s maximum current. For example, if a string has a maximum current of 10 amps, you should use a 15-amp fuse. It’s also crucial to select fuses that are compatible with your system’s voltage and environment.
Best Practices for Fusing Parallel Strings
When fusing parallel strings, make sure to follow local electrical codes and regulations. Typically, you should fuse each string at the DC disconnect or at the charge controller, depending on your system’s design. It’s also vital to label each fuse clearly and include a disconnect switch nearby to allow for safe maintenance and troubleshooting.
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