Hi all,
I have inherited a 3 panel array, parallel, that was not fused near the panels but rather were combined into an array and there is nothing other than an array circuit breaker that is roughly 25' away.
I have been told that the panels should have been fused near them, but the combiner box on the roof had no way for me to undo what was already done, and the wiring into the RV I am talking about is not accessible until way down the line when the array does go to a breaker.
accordingly, I have been advised to fuse each panel, which we can do, as they are standard MC4 connectors...and I did so with 15 amp fuses on each panel, per the advice of the trailer maker with whom I spoke about this recently, when I came to understand that not having local fuses, either right after the combiner box or at each panel prior to combining one the roof was a bad idea....but after some additional reading, I am not convinced I got the right advice.
I am seeing a variety of answers on the web to panel fuse sizes (these panels are astro energy 310 watt panels and are now 7 years old in the installation which we inherited from the original installers). The language below is right off of the spec sheet.
I understand that the fundamental spec is "aperage", but, please, and first, which current rating does one start with? is it:
Rated current at STC 8.40 A OR
Short circuit current at STC 8.92 A OR
Rated current at NOCT 6.42 A OR
Short circuit current at 6.90 NOCT
after that determination, I have seen various multipliers to determine fuse size....varying (this is all on individual panels)......with various levels intended to stop fuses that are too sensitive and blow too soon (these panels are on a roof and we are old and cannot climb up there to replace them ourselves) to ratings that make moot the safety that these fuses are supposed to give.
bottom line, please, and with thanks in advance, which aperage spec should be used to determine the fuse size, and how much above that individual spec (again, we are talking fusing each panel right at the roof, prior to going into the combiner box on the roof, after which, the wire just "disappears" into the econsystem of the trailer until it gets to the solar controller, and meets a breaker, prior to going into the controller?
sorry for the verbosity, but I hope I conveyed it all well enough.
many thanks.
OM
I have inherited a 3 panel array, parallel, that was not fused near the panels but rather were combined into an array and there is nothing other than an array circuit breaker that is roughly 25' away.
I have been told that the panels should have been fused near them, but the combiner box on the roof had no way for me to undo what was already done, and the wiring into the RV I am talking about is not accessible until way down the line when the array does go to a breaker.
accordingly, I have been advised to fuse each panel, which we can do, as they are standard MC4 connectors...and I did so with 15 amp fuses on each panel, per the advice of the trailer maker with whom I spoke about this recently, when I came to understand that not having local fuses, either right after the combiner box or at each panel prior to combining one the roof was a bad idea....but after some additional reading, I am not convinced I got the right advice.
I am seeing a variety of answers on the web to panel fuse sizes (these panels are astro energy 310 watt panels and are now 7 years old in the installation which we inherited from the original installers). The language below is right off of the spec sheet.
I understand that the fundamental spec is "aperage", but, please, and first, which current rating does one start with? is it:
Rated current at STC 8.40 A OR
Short circuit current at STC 8.92 A OR
Rated current at NOCT 6.42 A OR
Short circuit current at 6.90 NOCT
after that determination, I have seen various multipliers to determine fuse size....varying (this is all on individual panels)......with various levels intended to stop fuses that are too sensitive and blow too soon (these panels are on a roof and we are old and cannot climb up there to replace them ourselves) to ratings that make moot the safety that these fuses are supposed to give.
bottom line, please, and with thanks in advance, which aperage spec should be used to determine the fuse size, and how much above that individual spec (again, we are talking fusing each panel right at the roof, prior to going into the combiner box on the roof, after which, the wire just "disappears" into the econsystem of the trailer until it gets to the solar controller, and meets a breaker, prior to going into the controller?
sorry for the verbosity, but I hope I conveyed it all well enough.
many thanks.
OM
