I could not find that one but found this one (link below) which I think is similar. The specs say this is good to 1400W in 24V systems. I have 8 Panels @250W. I could not find another combiner box to meet 2000W for 24V. Am I missing something?
Off Grid for small Cabin
- Thread starter pbennison
- Start date
iamrich
Solar Addict
I was looking at that one as well, but I used the Midnight Solar box and three 15a breakers instead for the same reason (the wattage rating).
I got mine off eBay used for $90 shipped, and the breakers from:
I got mine off eBay used for $90 shipped, and the breakers from:
MidNite Solar - 15 Amp 150Vdc DC Circuit Breaker MNEPV15 - FREE SHIPPING | eBay
MNEPV15 15 Amp 150 VDC Din Rail Mount Breaker - 13mm Wide. Midnite Solar MNEPV15 15 Amp 150 VDC Din Rail Mount Breaker - 13mm Wide. 150VDC din rail mount breaker. For use in Magnum MMP Panels, Magnum MP Panels, Midnite Solar Inverter Panels, Midnite Solar combiner boxes.
www.ebay.com
rin67630
Solar Enthusiast
Rotating?
You mean tracking?
Regarding cost, we currently have got an absurd situation: the mechanics cos around a panel is exceeding the cost of the panels themselves.
Better two panels more than a complicated mechanic.
Please excuse my ignorance. I am really trying to understand this thoroughly.I was looking at that one as well, but I used the Midnight Solar box and three 15a breakers instead for the same reason (the wattage rating).
I got mine off eBay used for $90 shipped, and the breakers from:
MidNite Solar - 15 Amp 150Vdc DC Circuit Breaker MNEPV15 - FREE SHIPPING | eBay
MNEPV15 15 Amp 150 VDC Din Rail Mount Breaker - 13mm Wide. Midnite Solar MNEPV15 15 Amp 150 VDC Din Rail Mount Breaker - 13mm Wide. 150VDC din rail mount breaker. For use in Magnum MMP Panels, Magnum MP Panels, Midnite Solar Inverter Panels, Midnite Solar combiner boxes.www.ebay.com
In using this, I do not see where I would connect the PV connections. Do I use this in conjunction with the PV combiner box?
Hedges
I See Electromagnetic Fields!
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Yes, the breaker would be used instead of fuse holders in a combiner box similar to the one you linked above.
That box came fully assembled. Some come without the breakers, just a busbar to join them.
Or in any suitable box. You can buy DIN rail to go inside it.
The fuses are good for up to 600V. This breaker up to 150V.
I think your design has PV strings under 100V so either would work.
If you have only two strings (e.g. PV panels wired 2s2p) then either separate breakers for each string or one larger breaker for the single wire going back to charge controller would serve as a disconnect. So long as breaker is properly sized it will never trip anyway.
iamrich
Solar Addict
I cannot believe I don't have a picture of my combiner box
I guess I need to break down and take detailed pictures next time I am out at my garage. I would run out there but it's 40 miles away so... On my setup I have three pairs of 12awg wires coming into the box from my panels (3S3P). Each pair goes into the box. The negative wire goes to the negative bus bar in the box, the positive wire goes to a 15a breaker. This repeats three times. Then an 8awg pair comes out and goes to the controller, negative from the negative bus bar, positive from the positive bus bar than the three breakers are attached to.
iamrich
Solar Addict
Stolen from internet (no shame, not sorry )
)MichaelK
Solar Wizard
Well, the pipe sunk in concrete is 3.5" in diameter, and the pipe the frame is welded to is 4.0", so it is free to rotate (It does have locking lugs).
There is no mechanical tracking mechanism per say. In the morning when I want maximal power, I go out and rotate the frame East by hand. In the afternoon, I rotate West. I call it hillbilly solar tracking. Plus, it's also ammenable to seasonal adjustments.
It's simple, and it works. It's really only important on days when I need maximal power as early in the morning as possible, for example, pumping well-water. My rule is to pump water only when the incoming solar is >2000W. I can achieve that at 7:30am with rotation of my 4500W array. I'd need a lot more panels to accomplish that at 7:30 if it were fixed. I make the initial rotation at ~7:30am, another around 10:30am, and another around 1:30pm. It works.
On days I'm not pumping water, I just leave the array facing South and don't think about it.
My goals might not be your goals, so decide what works for you. I myself am very pleased with the performance of my system.
Ahhhh...OK...I think I get it now.
So, if I understand this correctly, you are using a breaker box to function as a combiner box also? I guess I don't need a breaker and a combiner.I cannot believe I don't have a picture of my combiner box
On my setup I have three pairs of 12awg wires coming into the box from my panels (3S3P). Each pair goes into the box. The negative wire goes to the negative bus bar in the box, the positive wire goes to a 15a breaker. This repeats three times. Then an 8awg pair comes out and goes to the controller, negative from the negative bus bar, positive from the positive bus bar than the three breakers are attached to.
View attachment 48677
iamrich
Solar Addict
Yes, the box performs both functions. It combines the three lines (~100v and ~8.27a each) into one line out to the controller (~100v and ~25a). With the three breakers, I can turn off each set of three panels individually if I need to work on them, or just to test that all three sets are putting out expected power. Basically trip two breakers and make sure I am seeing ~30-33V and 8.27a in full sun out of the one breaker. Then repeat that check on the other two sets.
rin67630
Solar Enthusiast
So if you rotate 2KW panels (~10m²) so easily by hand, what does a hurricane do?
Thank you, thank you, thank you. This is starting to make sense...I appreciate all the help.....
MichaelK
Solar Wizard
What I did was drill through the 4" pipe, thread on a 1/2" bolt and nut, then welded the nut to the 4" pipe. After unscrewing the bolts, I welded a T-handle onto the bolts, about 6" long. So, I can tighten down the arrays so they are immoble. They've withstood storms that have knocked down 18" oaks on my property. All the arrays have come through now for years with no damage whatsoever.
Here's a pic of one of my first generation (V1.4) single-row array mounts. You can see the T-handles about 10" or so above the seasonal adjustment spars. My dual-row design utilizes the same locking screws. They've worked for years now.
Attachments
I am getting closer to pulling all the equipment needed for my system. To date I have the following.
Midnite Solar-MNPV6 with Breakers
Growatt 24V SPF 3000TL LVM
8 280W Solar Panels (Facebook Marketplace)
AGM Batteries (Friend in Battery business)
Weather is getting better and we will be spending time up north very soon. Once I get the panels in place I can begin to measure wire requirements etc.
Looking forward to the next phase. Thanks everyone for all the help. I will begin posting pics as I make progress. I am sure there will be many more questions as well….
Midnite Solar-MNPV6 with Breakers
Growatt 24V SPF 3000TL LVM
8 280W Solar Panels (Facebook Marketplace)
AGM Batteries (Friend in Battery business)
Weather is getting better and we will be spending time up north very soon. Once I get the panels in place I can begin to measure wire requirements etc.
Looking forward to the next phase. Thanks everyone for all the help. I will begin posting pics as I make progress. I am sure there will be many more questions as well….
I have the panels installed on the roof. I also have the following.
Midnite Solar-MNPV6 with Breakers
Growatt 24V SPF 3000TL LVM
8 280W Solar Panels (Facebook Marketplace)
6V Duracell FLA Golf Cart Batteries (Friend in Battery business)
I am going to order.
-20 Feet 10 AWG Solar Extension Cables (Panels to Combiner Box) (Link)
-80 Amp ANL Fuse (Link)
-6 AWG Wire for connections (may be overkill?)
Outside the house I have an old cabinet I will use to house the connections from the combiner box, ANL Fuse, etc. to another box that will house the batteries. The Growatt will be inside the cabin wall behind this cabinet.
I would appreciate advice/comments and any pictures of existing systems that will help guide me to making this a safe reality.
Midnite Solar-MNPV6 with Breakers
Growatt 24V SPF 3000TL LVM
8 280W Solar Panels (Facebook Marketplace)
6V Duracell FLA Golf Cart Batteries (Friend in Battery business)
I am going to order.
-20 Feet 10 AWG Solar Extension Cables (Panels to Combiner Box) (Link)
-80 Amp ANL Fuse (Link)
-6 AWG Wire for connections (may be overkill?)
Outside the house I have an old cabinet I will use to house the connections from the combiner box, ANL Fuse, etc. to another box that will house the batteries. The Growatt will be inside the cabin wall behind this cabinet.
I would appreciate advice/comments and any pictures of existing systems that will help guide me to making this a safe reality.
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
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- 21,189
Are those polarized breakers?
When three or more PV strings are connected in parallel, OCP is required for each string in case it suffers a short (wires or bypass diodes in the panels) so excess current from other strings dumped into failed string is interrupted.
I believe polarized breakers aren't capable of providing that protection (because they arc and burn up when opened with reverse current.)
I think possible solutions are:
1) Gang the breakers together (piece of wire through the holes in breaker handles)
2) Blocking diodes
3) Fuses instead of diodes
4) Polarized breakers
Batteries - now that you say FLA not AGM, be sure to put the where corrosive fumes won't get to inverter.
Climate control or earth-sheltered to moderate temperature.
There should be a battery temperature sensor so inverter/charger adjusts voltage accordingly.
Set parameters according to battery manual.
Fully charge each 6V battery so they are same SoC before operating in series.
Determine what maximum DoD you want and set inverter to disconnect.
Control discretionary loads to avoid over-discharging battery. Maybe operate things like freezers only while the sun shines.
I am not sure if they are polarized or not? Could I use the MC4 Inline fuse?
Thank you....
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 21,189
Check the model number of the breakers, and look them up on Midnight's website.
Examine the breakers. If polarized, they have "+" and "-" on either end.
If you connect an MC4 fuse in line with breaker, it is possible breaker trips and catches fire without fuse blowing. All depends on how much current.
A stiff wire like a piece of welding rod should slip through hole in the handles, ganging them so when one trips it turns the others off too. The others are carrying current in forward direction so will break the arc successfully.
There are breakers with 2 to 4 poles ganged. I have one with 6 poles ganged, because it is 100V breakers meant to segment and open a 600V string. It just has a metal rod through the handles. I plan to repurpose it for connecting 6 lower voltage strings in parallel.
Examine the breakers. If polarized, they have "+" and "-" on either end.
If you connect an MC4 fuse in line with breaker, it is possible breaker trips and catches fire without fuse blowing. All depends on how much current.
A stiff wire like a piece of welding rod should slip through hole in the handles, ganging them so when one trips it turns the others off too. The others are carrying current in forward direction so will break the arc successfully.
There are breakers with 2 to 4 poles ganged. I have one with 6 poles ganged, because it is 100V breakers meant to segment and open a 600V string. It just has a metal rod through the handles. I plan to repurpose it for connecting 6 lower voltage strings in parallel.
Hedges
I See Electromagnetic Fields!
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- 21,189
The parts are UL or ETL listed, individually tested and shown to work reliably, as they were intended to function.
The polarized breaker burns up if opened while carrying full reverse current and voltage. It works if carrying forward current.
I don't believe the breaker assembly has ever been tested with 5 strings of PV that are good, shorting out the 6th string so the other 5 dump current into it.
I shared my concern with the vendor and explained my proposed modification to make it work. They brushed it off.
I think somebody said future codes require non-polarized breakers for this application.
I suggest getting a suitable stiff wire (like a piece of gas welding rod) and slipping through handles to gang them, like the ganged breakers they sell
The polarized breaker burns up if opened while carrying full reverse current and voltage. It works if carrying forward current.
I don't believe the breaker assembly has ever been tested with 5 strings of PV that are good, shorting out the 6th string so the other 5 dump current into it.
I shared my concern with the vendor and explained my proposed modification to make it work. They brushed it off.
I think somebody said future codes require non-polarized breakers for this application.
I suggest getting a suitable stiff wire (like a piece of gas welding rod) and slipping through handles to gang them, like the ganged breakers they sell
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