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 on caravans and motorhomes, 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:
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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 (AS3001) for solar panel installations on caravans and motorhomes 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.
Note: These requirements to meet these rules outlined in the Australian Standards apply to installation built or had this section of the installation upgraded after 18 November 2023. Replacing like for like is no need to meet updated standards.
Cheers, Landon
14 Comments
If placing 10 panels upon the roof of a caravan, are we running 10 cables down, fused at the panel and then to a fuse box then an isolator? Or can we use the MC4 fuse solar connectors, then cables joined into a string and down to the isolator so only 2 cables coming through the roof? Which is the compliant way? We are reading it as the second version of my comment.
Hi ZeroGrid team, in particular – Landon. I appreciate the effort you’ve gone to break down the new regs under AS/NZ3001.2022 . I’m curious about where the caveat at the Note above (replacing like for like) leaves me, with this scenario (I did leave a post on your FB site, but prefer response here rather than dealing with the regular FB warriors, LOL). OK. In August 2023 I had an upgrade done on my solar. It previously was 4 Enerdrive 180w glass panels parallel, hooked up to Enerdrive 40A DC-DC charger. The upgrade removed the solar input from the DC-DC, and installed 2, 30A Enerdrive MPPT controllers. and added another 2, 180w panels of the same type. These were put into 2 arrays, each of 3P connecting to one of the controllers via a CB, and downstream of the controller(s) is a fuse connecting to the battery busbar. The construct of the van I have, has a rooftop solar junction box, where the panels are combined into what looks to be 10awg, possibly 8awg wire – to the controller(s) via the mentioned CB’s. The install was a bit lacklustre, with the controllers’ heatsinks tucked up hard against the wall under the couch, with no ventilation, and no way to easily monitor what the controllers are doing. So, I have replaced these with Victron 100/50 MPPT controllers (SmartSolar type with the integral BT) – and mounted these with fans and a PWM fan controller. The fans kick in when the sensor picks up 30oC. OK, so the solar junction box on the roof is a bit small to accommodate a fuse on each panel + line (an ideal location for them, as that is “as close as possible to the junction point” as one could get). So – given all I have done is replace the controllers’ function (like for like) – and the upstream CB’s and downstream fuses exist – am I required to fuse each panel?
If i have 2 in series and another 2 in series and then put them in parallel, do i need to fuse all 4?