How do I wire this solar panel? (OGRE B180-J24)

[oldguy]

Mike- thx for your reply. But again, I have all of my panels in parallel (combined at a j-box). A 12 volts system as it were. If I put a blocking diode at each panel then those in shade will not be subject to damaging currents from panels in sun. No? I've been taking VOM measurements at the charge controller, the battery, and my inverter. Seems like when one panel is in shade the voltages remain at the proper level (ie a function of the battery charge level). Thus, I think everything is working fine...but if my bypass diodes or individual panels are being stressed I'd be happy to fix that with blocking diodes at each and every panel...and can "afford" the loss in production. (I've added panels to be in sun to keep my load requirements met). Won't that protect the bypass diodes? I understand that my charge controller has a blocking diode (or equivalent function)...but I don't want to lose any of my panels due to reverse currents honking up my bypass diodes. None of my panels exceed 10 A at MPP and I've ordered 15 A diodes. What say? Thx....

[Mike90250]

Blocking diodes won't help anything with panels in parallel, blocking diodes only prevent the battery from discharging into the array.
a blocking diode at 8amps will dissipate about 8 watts, which must be heat sunk.

HOWEVER, with more than 2 panels in parallel. you need OverCurrent protection ( fuse or breaker). This is the Series fuse spec on the back of your panel. If a panel develops a defect, a parallel panel can feed power into it, and that's just fine, 1 panel can dissipate 2 panels worth of power. Adding a 3rd panel the situation changes as there is now enough power to ignite the defective panel or surroundings. When OC protection is there, chances of fire are limited. I prefer to use breakers, because it makes it easy to switch off panels/strings to insure all are working well.

https://www.midnitesolar.com/products.php?menuItem=products&productCat_ID=9&productCatName=Combiners

I don't know where you are wanting to go, adding a bunch of diodes and heat sinks adds unneeded complexity and failure points to the system. and more connections that can fail.

[bcroe]

If I put a blocking diode at each panel then those in shade will not be subject to damaging currents from panels in sun. No? I've been taking VOM measurements at the charge controller, the battery, and my inverter. Seems like when one panel is in shade the voltages remain at the proper level (ie a function of the battery charge level). Thus, I think everything is working fine...but if my bypass diodes or individual panels are being stressed I'd be happy to fix that with blocking diodes at each and every panel...and can "afford" the loss in production.

Shaded panels do not reduce significantly in voltage, just in their ability to
back it up with current. So your undamaged but shaded panels will continue
to output a much reduced current, NOT absorb current from the unshaded
panels. Blocking diodes have nothing to do, but hurt your efficiency, esp in a
low voltage system.

Bypass diodes do not work so hard in single panel strings, as losing a third of
the panel drastically reduces available current, at the voltage the unshaded
panels are running at. In a high voltage string (mine run at 400V) one third
panel loss will not reduce the current flowing much.

On the other hand, over current devices are needed to prevent a damaged
panel from receiving higher currents from fully producing panels. At higher
voltages I use fuses which may be switched out, circuit breakers Mike
recommended are fine for low voltage battery systems. Bruce Roe

[oldguy]

I've had this small off-grid system running for about 4 years now. I've got 10 amp fuses at the j-box...one for each panel before combining run going to charge controller. I found and reread your post from a month or two ago and seem to recall that if a panel is shaded other non-shaded panels will attempt to feed current into the shaded panel(s). Is that not correct or not what you stated? I have a rack of 4 panels (all panels wired in parallel, and top to bottom mounted) but this time of year no sun gets on the bottom two panels because of a tall fence. Thus, this year I've relocated those two such that they are in sun while other shade issues (palm trees this time of year) affect the top two and vice-versa (as the sun sweeps the sky)...so I always have enough production on sunny days to do what I want to get done.

So I definitely am getting your vibe to not add blocking diodes...so did I misinterpret your statement about "heating up and eventually failing" about the bypass diodes due to shade?

BTW, I spent a lot of time on this forum and others trying to figure this dern question out before posting here. Appreciate your help!

[Mike90250]

I've had this small off-grid system running for about 4 years now. I've got 10 amp fuses at the j-box...one for each panel before combining run going to charge controller. I found and reread your post from a month or two ago and seem to recall that if a panel is shaded other non-shaded panels will attempt to feed current into the shaded panel(s). Is that not correct or not what you stated?

Panels in parallel will not try to backfeed a good or shaded panel. A damaged panel will rely on a fuse or CB to protect it from becoming a flame generator .
Fuses are designed to interrupt current. Most fuse holders nowdays are "touch safe" so you won't get shocked. But the fuse holder is not rated to interrupt current, so they cannot be used as a switch to disconnect panels for testing, Midnight has UL qualified 300VDC breakers ( 2, 150V ganged together in series ), but after 300V, fuses are the ticket.
Both my 130V array and 180V arrays have breakers ( 150V & 300V )

I have a rack of 4 panels (all panels wired in parallel, and top to bottom mounted) but this time of year no sun gets on the bottom two panels because of a tall fence. Thus, this year I've relocated those two such that they are in sun while other shade issues (palm trees this time of year) affect the top two and vice-versa (as the sun sweeps the sky)...so I always have enough production on sunny days to do what I want to get done.

So I definitely am getting your vibe to not add blocking diodes...so did I misinterpret your statement about "heating up and eventually failing" about the bypass diodes due to shade?
BTW, I spent a lot of time on this forum and others trying to figure this dern question out before posting here. Appreciate your help!

Panel bypass diodes are seldom rated for weeks of use on a hot roof , they have no heatsinking and thus fail often.