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diy solar

Dc disconnect should be out by the panels or inside?

Toddburkett

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I will have four sets of 6 (250 watt panels )in series and then two sets out of those paralleled leading to two sets of wires to the house of 200 V DC! One set for each side of my MPP controller 6.5 K
My question is whether or not I should put my DC combiner box outside by the solar panels or inside the house I had already purchased solar panel connectors to parallel them before I decided to buy the DC combiner box
 
I had already purchased solar panel connectors to parallel them before I decided to buy the DC combiner box
If you have the panels connected in parallel, what are you planning on combining in you combiner box? Or will the combiner box just be used to house a disconnect?

As for location, I would try to keep the disconnect weather tight or out of he weather. Next I would shoot for convenience and for most of what I do (testing and tinkering), that disconnect is near my SCC and battery.

Otherwise, if your combined strings were high amps and a long distance to SCC, shortening the high amp run would allow smaller/cheaper wire. But 2 strings combined to 2x your Isc should be below 20A (unspecified in OP).
 
If you have the panels connected in parallel, what are you planning on combining in you combiner box? Or will the combiner box just be used to house a disconnect?

As for location, I would try to keep the disconnect weather tight or out of he weather. Next I would shoot for convenience and for most of what I do (testing and tinkering), that disconnect is near my SCC and battery.

Otherwise, if your combined strings were high amps and a long distance to SCC, shortening the high amp run would allow smaller/cheaper wire. But 2 strings combined to 2x your Isc should be below 20A (unspecified in OP).

I think the combiner box is probably where the two strings will become one; at least that how I would do it. However, I will be putting in a separate disconnect switch inside the building next to where the solar power connects to the charge controller/inverter.
 
I have some in-line fuses I bought before I realized I wanted to get a DC disconnect combiner as planned right now going to do the paralleling by the array because I just have two pairs of wires in my underground cabling. So is it fine to put the in-line fuses out by the array? Are they just on the positives? Before you parallel?
 
So is it fine to put the in-line fuses out by the array? Are they just on the positives? Before you parallel?
My understanding of the consensus here is twofold:
First, the fuse protects the wire, so closer to the source (array) is preferred to accomplish this.
Second, folks mostly recommend at least a switch (cutoff) between array and SCC, but the addition of a fuse is mostly optional. I usually recommend breaker because it is both fuse and switch. (Someone correct me if this is not the consensus).
I usually only fuse the positive. Some folks use double pole breakers and or fuse both.
 
Each inverter gets 2 strings in parallel?
Then no need for fuses or breakers. Wires from each string should have ampacity at least Isc x 1.56, wire after combining at least Isc x 1.56 x 2.

I like to disconnect both ends of PV string before working on anything.
200VDC switch or breaker gets a bit hard to come by.
A 2-pole breaker rated 150VDC per pole would open both. If "polarized", get polarity of each pole correct so if a short at SCC and PV dumping current into it, breaker will reliably interrupt current.
 
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