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Randyretired

Solar controller recommendation

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On 2/11/2019 at 10:58 AM, Randyretired said:

Your responses have been great and I really appreciate your help.  I have narrowed my choices down to 3.

Victron 150 85 @$687

Midnight Solar 150 SL 96A@ $575

Outback Flex Max @ $459

All 3 seem to do about the same thing but there is a significant price difference.  Many have suggested the Victron but is it that much better?  I got these panels for $.35 a watt and I am trying to keep the overall cost down.  On the other hand we will probably boondock all summer and I don't want any problems.

For simplicity and shading I was going to wire all 4 panels in parallel.   The feed to the controller is 12' of #2 copper so voltage loss is minimal.  Each panel will be wired to the combine box with #10 copper.

 

The MidNite Solar will take up to #4 wire connections. However, #4 AWG THHN is rated @ 95A.

I also wired my panels in parallel, but instead of a combiner, I ran each panel into my PV fuse box which is less than a foot from my MidNite Classic 150.

Also, I like using PV "sizing tools" like this MidNite Classic Sizing Tool.

BTW, instead of Handy Bob, try John Mayer's site.

Edited by Zulu

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1 hour ago, Zulu said:

 

I also wired my panels in parallel, but instead of a combiner, I ran each panel into my PV fuse box which is less than a foot from my MidNite Classic 150.

 

If you have space and budget to put in a PV breaker box you won't regret it. When I was doing installs I always tried to do this on larger systems. At the time it was pretty uncommon, but far more common - and better components available - now. 

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I think I used transatlantic cable on my panels. It's a tad bit crowded . . .

 

solar_09_wires_to_bigbabybox.jpg

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9 hours ago, Jack Mayer said:

If you have space and budget to put in a PV breaker box you won't regret it

FWIW as a retired electrical power distribution design engineer I HAVE TO AGREE in theory and principle even if its often NOT done...

There's not a thing wrong choosing to provide overcurrent protection so the current flow in a wire CAN NOT exceeds its capacity to conduct X amps of current and NOT OVERHEAT AND START A FIRE. Of course a panel has its own inherent protection in that its ONLY CAPABLE OF PRODUCING X AMPS MAX INTO A "SHORTED" LOW RESISTANCE  CIRCUIT, so if the  chosen wire size can withstand that amount of current (max amps the panel can produce) and not overheat or degrade, overcurrent protection on top the roof is less critical (though it might interrupt that higher current and possibly reduce harm to the panel). That's UNLKIKE protection at the battery which can produce thousands of amps yet its wiring is often MUCH LESS then that. Now that's where proper overcurrent protection is critical IE a huge battery versus a small panel. Take a look at the panels max current and if that's less then the wires ampacity, additional overcurrent protection is less critical.........…. But still no harm in providing overcurrent protection...……..

ALSO an overcurrent protection device only protects the wire downstream and afterwards meaning the combiner box with breakers on top the roof not at the solar charge controllers input. HOWEVER a disconnect means is good to have right there at the controller to shut off all the solar as needed.

 Hey there's no harm in over engineering and no harm in using safe wiring methods even where not specifically required. Its ones own life and risk and  choices to make.

John T Longgggggggggg retired EE and rusty on the latest codes and not any solar expert so do as the experts suggest NOT me lol

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Jack Mayer and Zulu, your wiring and breakers are nice!  Since I already have #2 from the roof to the controller I just purchased a 4 to 1 MC4 connector  to connect my 4 panels.  Not near as nice as yours but I think it will be useable. Hopefully the 12" or so of #10 out of the MC4 won't cause a significant loss before the #2 wire.  I will have a fuse into and out of the controller.

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