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

[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.

[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!

[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

[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.

[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 are only sized large enough to support temporary operation. PV panels are supposed to be placed in full sun. If one panel in an array is shaded, depending on the size of the array, the shaded panel will throttle the entire array, or be burned out ( by the functioning panels exceeding the reverse voltage of the P-N junctions that make up a PV panel) So Bypass Diodes came to be, to allow damaging power to not smoke the shaded panel. However, the small, inexpensive diodes supplied with panels, eventually fail from stress/heat, so there exists a market for replacements.

Blocking Diodes serve a different function than bypass diodes. They Block the slow discharge of the batteries at nightime, from leakage through the P-N junctions in the PV array. All modern charge controllers provide this function and blocking diodes are no longer needed.

[oldguy]

Since this is a recent thread I have a question about blocking diodes. I do not plan on making any changes in the near future to my equipment so only interested in my blocking diode question below. I seem to remember a recent post that Mike90250 responded to on a similar question. I'm a retired EE so get the I and V thing!

I have several panels in a small off-grid system. Non-MPPT controller. All panels in parallel. Especially this time of year (low sun, palm trees in neighbor's yards, etc) I cannot prevent shade from impacting my panels and different ones at different times of the day. I have more than enough power to run the loads I want to run but am concerned about possible damage to panels in shade. I think Mike had mentioned that currents try to force their way in (path of least resistance) and eventually will burn out the bypass diodes. Thus, my question is (and yes, loss of a few watts is ok) should I be running blocking diodes on each of my panels?

Thanks in advance...

[FishFilet]

That is a poorly written, very old, article. Since the mid 80's Charge Controllers provide the nighttime Blocking diode function.

Because modern panels include Bypass diodes,extra diodes are not needed between panels.

Shade on even a small portion of a panel can drastically reduce output, and that shaded are will often activate the bypass diode(s). This is less than optimal, because there is no harvestable energy in shade, so the simple solution is to remove the item causing the shade, allowing the panels to produce full power

Yes well that's not the actual article. It was article like this one however. It doesn't really matter though. Thank you for all of the help.

[Mike90250]

That is a poorly written, very old, article. Since the mid 80's Charge Controllers provide the nighttime Blocking diode function.

Because modern panels include Bypass diodes,extra diodes are not needed between panels.

Shade on even a small portion of a panel can drastically reduce output, and that shaded are will often activate the bypass diode(s). This is less than optimal, because there is no harvestable energy in shade, so the simple solution is to remove the item causing the shade, allowing the panels to produce full power

[FishFilet]

Diodes in the panel's Jbox are for bypass between rows of cells. Generally, bypass diodes are NOT installed between panels.
better solar stores sell bypass diodes to repair burnt diodes in a Jbox

I see. I think I was referring to an article much like this one although it was talking about when a series string of panels gets partially shaded that the current for the entire string drops. Adding bypass diodes would help with that.

https://sinovoltaics.com/learning-center/off-grid/blocking-diode-bypass-diode-solar-panels/

[Mike90250]

Diodes in the panel's Jbox are for bypass between rows of cells. Generally, bypass diodes are NOT installed between panels.
better solar stores sell bypass diodes to repair burnt diodes in a Jbox

[FishFilet]

Shame they did not answer. THe companies I’ve dealt with have answered me when I E-Mailed them. Guess I was lucky.\\

I did not think whether the panels or batteries mattered if they were positively grounded until electronics got added to these, and the components determined that.

It has something to do with high efficiency all back contact solar cells and surface polarization. Here is some info.

[chrisski]

Shame they did not answer. THe companies I’ve dealt with have answered me when I E-Mailed them. Guess I was lucky.\\

I did not think whether the panels or batteries mattered if they were positively grounded until electronics got added to these, and the components determined that.

[FishFilet]

I am curious about the unlabeled pins, I’ll call them 0 and 5. Don’t now if you have something like this, but I have a smaller 50 ah lithium, homemade solar generator which has a MPPT I could hook a panel. I’d see how it did after a day of charging on pin 1 and 4.

Have you tried contacting the OGRE company? They seem to market themselves for stand alone panels to power a small battery pack off grid.

The unlabeled pinst don't give any voltage. Maybe they are grounded to the frame? I'll check that next time i can but they don't give out any voltage.

I did ask these questions to the OGRE company via email but have not gotten a response.

I did hook to pins 1 & 4 and it didn't seem to help. I'm going to look into if they need to be positive grounded because there is mention of that on their site. I just don't know anything about that. That's another thread however.

Next time I am around the panels I will check the current output with a multimeter of the shorted leads.

[FishFilet]

I think you should connect to the highest voltage points, bracketing all the
bypass diodes, 1 & 4. Bruce Roe

That's what i am thinking. I just didn't wanted to see what others thought. Thank you.

I was wondering what the diodes were for. I was reading about bypass diodes between panels. Do these work the same way? letting the panel have some output when part of the panel is in the shade?