Do You Need a Fuse on Every Solar Panel? Clarifying the New Australian Standards

If you’ve been hearing mixed messages about the new Australian Standards for solar panel installations, you’re not alone. The standards can be complex, and since they require a purchase to access, confusion is common. Let’s clear up the confusion with accurate information.

Understanding the Rules for Overcurrent Protection

The new rules for overcurrent protection in PV arrays are designed to ensure safety and reliability. Here’s a simplified explanation of the requirements:

Protection Against Circulating Currents

If your PV array has three or more strings (a string is defined as one or more panels connected in series), each string needs its own overcurrent protection. This is crucial to prevent circulating currents within the array, which can cause damage.

Location and Rating

The protective devices should be placed as close to the string junction point as possible and should be rated at no more than 1.5 times the string’s short-circuit current capacity.

Practical Applications

Let’s break down what this means in practical terms:

When Fuses Are Not Required

Example 1: If you have two solar panels connected in parallel to a solar charger, you do not need individual fuses.

Example 2: If you have two panels connected in series, you also do not need individual fuses.

When Fuses Are Required

Example 3: If you have three or more panels connected in parallel, each panel must have an individual fuse on the positive conductor. 

Is an Isolator Required on the Solar Charger?

Yes, the new rules state that an isolator or current limiter is required on the incoming solar charger. This serves two main purposes:

• Protection: It protects the solar cable from overcurrent.

• Safety: It provides a point of isolation, allowing you to safely work on the system if needed.

Recommended Products

For those looking to comply with these new standards, I recommend the following isolators:

• Installation Kit with Solar Isolation Circuit Breaker and Enclosure: These can be found here.

The circuit breaker should be appropriately sized to match and protect the cable. For instance, a 25A breaker is suitable for a 4mm² cable (or its AWG equivalent).

Conclusion

Understanding the new Australian Standards for solar panel installations is essential for ensuring the safety and efficiency of your PV system. Remember, not every panel needs a fuse, but overcurrent protection is critical for arrays with three or more strings. Additionally, an isolator on the incoming solar charger is necessary for protection and safety.

By following these guidelines, you can ensure your solar installation is compliant and safe. If you have any more questions or need further clarification, feel free to reach out or leave a comment below.

Cheers, Landon