But… Since the National Electric Code specifically makes a call on the issue of fusing an array, we really should follow that in our attempt to design and build a high end camper electrical system. Even if a cell burns out, usually the panel will still work. It’s pretty much just a bunch of Silicon cells fused together between some laminated glass connected to some diodes and wires. Fusing is required for a redundancy in the event that one of the diodes fails or something else goes wrong with the panel. There are diodes in MOST solar panels that do not allow most of the above scenarios to happen. Fusing a Camper Solar Array – Final Thoughtsįaults in solar panels are quite rare. If it WASN’T fine… there would be an electrical code or standard saying something about it. This would mean that the area of the panel experiencing the fault would potentially have 20.2 amps flowing to the affected area.Īlthough there are 15A fuses in the proper locations, the current going from panel #1 into panel #2 would not be enough to blow either of those fuses.Īlthough this is not ideal, it’s nearly impossible to avoid when using two panels or two series strings in parallel and this setup is NOT forbidden by the National Electric Code so it’s one of those things you just have to sit back and say It’s fine. In the event that panel #2 had an internal fault, the power produced in panel #1 would seek out the path of least resistance and flow into panel #2. This scenario WOULD indeed require use of fuses in this array because the array short circuit current of 20.4 is greater than the 15A Maximum Series Fuse rating of the panels used. Here is an example of a setup that would NOT benefit from fuses, but DOES require fuses according to electrical code. Electrical code is sometimes a bit more conservative but is there for a reason. When this happens… ALWAYS abide by electrical code. Sometimes, there will be a discrepancy between what would happen in a real-world scenario and what is required by code. Electrical Code vs Real World Discrepencies This is why a fuse, by code, is not required in this scenario. Make the fuse constantly experience nuisance blows under normal operating consitions.Sure, a 10A fuse would indeed be between those two values, but the difference of. Ultimately… it wouldn’t do anything… In the event of a short circuit, 10.2A would flow. Now… What if you just wanted to add a fuse ‘just to be safe’: If a short circuit or other malfunction were to happen inside of one of the solar panels, since the short circuit current of the array is 10.2A, it’s safe to say that the panel itself is designed to handle this short circuit event as the short circuit current cannot exceed the maximum fuse rating of the panel. Since the Maximum Series Fuse Rating is 15A, we know that the wires, diodes, connectors, and other internal components of the actual solar panel can handle a max of 15A. Each solar panel has a short circuit current of 10.2A, and operating current of 9.8A, and a Maximum Series Fuse Rating of 15A. The diagram above shows 3x 200W panels wired in series. Fusing this type of array adds no additional protection or benefit, and here’s why: If the Short Circuit Current of the solar array is less than the Maximum Series Fuse Rating of the solar panel, the array does NOT need to be fused. Why Would A Solar Array NOT Need to Be Fused? That is why, by code, fuses are required in this array. This means that there would be 20.4A flowing to panel #3 EXCEPT, that since we installed a 15A fuse protecting panel three’s circuit… that fuse would blow and isolate the problem panel to a short circuit that is within the maximum short circuit parameters of that panel. In the event that panel #3 develops an internal short or fault of some kind… panels #1 and #2 would seek out the path of least resistance (the point of the short) to complete their circuits). Now… What if there were fuses attached to each of the positive wires from each solar panel where they connect to the MC4 Combiner? This means that there would be 20.4A flowing to panel #3, combined with the 10.2A FROM panel #3 where there could POTENTIALLY be 30.6A flowing through the short, which is over 15A higher than the max amperage rating of the panel and is more amperage than the panel is designed to handle. Here is what happens in an un-fused array if a short were to somehow happen inside of the panel: In the event that your solar array needs to be fused because the Array Short Circuit Amperage is greater than the Panel maximum series fuse rating… you must fuse your array at the point where the panels or series strings get combined to prevent potential fires or overheating due to a faulty panel.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |