I'm generally committed to building high voltage / low current strings these days. As such, I'm not wiring panels in parallel through a combiner and bus bar setup. My requirements have been: A 3R or better enclosure; a DIN rail mounted breaker or a high voltage fuse; a means of providing manual disconnect at the array; an SPD. These are all ground mount. I have no interest in roof mounting and so do not need a rapid disconnect (NEC). I've been building my own boxes since I've seen nothing pre-built along these lines. Midnite has nice boxes, but they are all about combining. I will oftentimes put two strings through the box with all the aforementioned doubled up, but when I do that I want two out and not combined. Has anyone run into commercial products that come close to this? My boxes are cheap to build out of components, but I would rather just buy something and save the time. Thanks in advance.
Non-Combiner Box at Array Location
- Thread starter ak1a
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Northernchateau
Solar Enthusiast
What are you calling "High Voltage"?
Hedges
I See Electromagnetic Fields!
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It is only a busbar that makes the Midnight connect things in parallel. Beyond that, it is a DIN rail mount for fuses or breakers.
I just bought a 420A combiner. By unbolting a cross piece it would be 2x 210A. Removing busbar and it is 24x individual 30A fuses.
You can buy busbars to combine just a few in parallel.
I just bought a 420A combiner. By unbolting a cross piece it would be 2x 210A. Removing busbar and it is 24x individual 30A fuses.
You can buy busbars to combine just a few in parallel.
Pilot Bob
New Member
Just a question, how are you wiring the SPD with multiple strings? I need to do the same thing. Buy a box, install dc breaker for each string, but not sure about the SPD.
Hedges
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Separate SPD for each MPPT input. If multiple strings paralleled in a combiner, could connect SPD like one more string at that location, or elsewhere.
What I've put in an AC breaker panel was on its own breaker, which does mean the protection can be disconnected. But need to shut off if it shorts and draws excessive current.
What I've put in an AC breaker panel was on its own breaker, which does mean the protection can be disconnected. But need to shut off if it shorts and draws excessive current.
Pilot Bob
New Member
I have 4 mppt’s between 2 inverters. I have 19 modules. Is it best to maximize 1 Mppt per inverter, or run 4 strings so each Mppt has input? I will have ac in for charging batteries if solar is unable. Thanks!
Hedges
I See Electromagnetic Fields!
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An MPPT can handle one or more PV strings of equal voltage.
It is OK to have two strings of different orientation. About 2% lower power harvesting, but higher utilization of SCC or inverter.
What isn't OK is to have one of the paralleled strings heavily shaded. About 10% difference in shading between strings is OK, but if one 50% shaded, would lose production.
Distribute strings between two inverters to avoid clipping. Same for MPPT.
Likely no benefit to more strings on one MPPT and none on other. At the least, greater IR losses in its inductors and transitors.
It is OK to have two strings of different orientation. About 2% lower power harvesting, but higher utilization of SCC or inverter.
What isn't OK is to have one of the paralleled strings heavily shaded. About 10% difference in shading between strings is OK, but if one 50% shaded, would lose production.
Distribute strings between two inverters to avoid clipping. Same for MPPT.
Likely no benefit to more strings on one MPPT and none on other. At the least, greater IR losses in its inductors and transitors.
