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diy solar

DC Disconnect / Combiner / Isolators... what to buy?

hamburgerman

New Member
Joined
Aug 9, 2021
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I'm working on final design for my PV system I've posted about previously. It is a ground mount system, ~200' from my house, consisting of 46 total panels. The panels will be wired in a series/parallel as shown in the diagram, to result in 3 separate strings running a theoretical max of about 28A @ 387V DC.

My Sol-Ark technically has a PV disconnect built in, but it will be in my basement (and thus not utility accessible). To make everyone happy, and to maximize safety and the ability to shut off power if I ever need to work on the lines for some reason, I want to at least have one exterior disconnect. Logically, I'd place it by the meter, before the inverter, so it's all utility accessible and all that good jazz.

I imagine there would also be some benefit to having a disconnect over at the array itself, since it's so far from the house. My original thought was to use MC4 Y connectors to create my parallel strings, but I'm wondering if it's a better idea (or even just a straight up requirement) to instead use a combiner/disconnect box on each string. They could be mounted by the array, so you could shut off the PV power at either end. I've attached a wiring diagram of what I mean.

I have a couple questions about this, because I'm having some trouble finding the right products to fit this design.
  1. For the combiner/disconnect boxes on the array end, what is a good product to use, that would handle merging two ~14A @ 387V into one ~28A @ 387V string?
  2. For the disconnect box at the house, I need to keep the strings separate and not combine them, as each will go to it's own MPPT on the sol-ark. Any suggestions on a good option to handle disconnecting 3 separate ~28A @ 387V strings?
  3. Am I making some other hilariously stupid mistake / oversight here? :)
 

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