As I'm gathering pieces for my SP install, the disconnect between the panels and the controller should it be a switch or CB? Since the panels are limited to max open circuit current and the wire between the panels and the controller is rated for the combined max current out of the panels. I was planning on using a switch just ease of mounting but I have found a surface mount Dc breaker.... opinions?
Solar Panel disconnect, switch or circuit breaker
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twistedtree
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A switch is all you need, but often a breaker is more readily available in the required voltage and current rating, and works just as well. Just double check the DC rating of whatever device you get. Larger panels will operate up to around 70-90VDC, and it can be difficult to find switched or breakers rated for that.
Ken E.
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Consult your controller's owners manual, but what you'll likely find is that a circuit breaker is required between the panels and the controller and another required at the batteries. In my case, my controller is 40 amp, and the breakers specified are 40 amp. Blue Seas sells 40 amp breakers and I'm sure there are many other brands. Be sure the you install wiring that is big enough, which your manual will also specify.
No circuit breaker required for the reasons noted by the OP. But for the life of me I can't see why you need a switch. If you want to isolate one or more panels then unscrew the terminal or unplug the MC4 connector and unhook and tape the hot wire. Even if the wire touches a ground it won't do anything and won't hurt anyone.
I have done a half dozen boat and RV solar installations for myself and friends and didn't include a switch. I also never needed to isolate the panels for maintenance.
These comments apply to 12/24V panels only.
David
I have done a half dozen boat and RV solar installations for myself and friends and didn't include a switch. I also never needed to isolate the panels for maintenance.
These comments apply to 12/24V panels only.
David
twistedtree
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I think OK for lower voltage panels. But I once removed a wire from a larger panel and it arc welded itself to the screw terminal.
twistedtree
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Again, just check the DC voltage rating carefully against the max voltage you panels can achieve. My panels needed a 90VDV rating, and it was a bit of a trick to find.
JDCAVE
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We put a Blueseas breaker in between the MPPT and the batteries. I don’t recall the size. 30-40 amps, I think. It is useful to have as we always turn it off when traveling. I have found on several occasions, that I loose my instruments when the alternator shuts down because the batteries are fully charged. I’m not sure the specifics of this and I’m sure I could do an adjustment on the Balmar controller for the alternator, but I have not yet done that.
Jim
Jim
twistedtree
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A breaker is definitely required on the battery side since the battery is essentially an unlimited source of power - at least for long enough to cause some serious damage.
The panels are not located in an easily accessible area, would need to get a step ladder to reach the connectors.
Ken E.
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I'd be interested in the solar setup on your new Nordhaven since you're designing it from the ground up.
fryedaze
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You can use a double pole breaker. Wire the solar panel to controller on one side and the controller outlet to the other pole.
https://www.trawlerforum.com/forums/showthread.php?t=19205
https://www.trawlerforum.com/forums/showthread.php?t=19205
twistedtree
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It's relatively straight forward.
Four Panasonic 335W panels, about 60V @ 5.7A each at max power, and pushing 90V with no load and edge condition lighting, which is what you need to allow for.
Each panel goes to it's own Victron 100/20 charge controller. This is the first time I have used per-panel charge controllers, and am hopeful it will give the best shadow immunity possible.
There is a disconnect switch at each controller to disconnect the solar panel, and there is a breaker between each controller and the main DC bus bar.
That's about it.
Four Panasonic 335W panels, about 60V @ 5.7A each at max power, and pushing 90V with no load and edge condition lighting, which is what you need to allow for.
Each panel goes to it's own Victron 100/20 charge controller. This is the first time I have used per-panel charge controllers, and am hopeful it will give the best shadow immunity possible.
There is a disconnect switch at each controller to disconnect the solar panel, and there is a breaker between each controller and the main DC bus bar.
That's about it.
twistedtree
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Interesting approach. I suppose as long as the required breaker rating is the same on both sides/poles, why not.
Ken E.
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TT...Very conservative and lots of redundancy, which is the name of the game IMO.
TT how are configuring the charge parameters on the controllers, same as the inverter/charger? I know typically they are based on battery specifications, I was wondering if the solar and I/C would interfere with each other especially in the float mode....
dhays
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I only installed one 365W panel and back fed the charge current from the controller through the positive bussbar to the batteries. I had an extra 50amp breaker in the panel and I used it as a cutoff for the solar. Not necessary but it was easy to do.
twistedtree
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I'll program all the charger sources the same, geared to LFP batteries. This has worked fine in anther land-based system I have, so I expect will work again. LFP charging is a bit different, but still achievable with most programmable chargers.
In addition, the battery system is capable of telling charge devices when to stop, so I will hook that up to. This will be my first time using both together, so we will see what discoveries (aka surprises) come up along the way.
