Please look over my solar diagram for Van RV

MysteriousFoundationMysteriousFoundation Posts: 22Registered Users ✭✭
I decided to go with 5x 175W panels instead of 4x, and I'm also not going to tilt them at first. This requires getting the TS-MPPT-60 and not the 45.

The layout and wire lengths in the diagram are not to scale. Everything it going to be as short as possible. Mostly under one foot per cable. All battery interconnect cables will be the same length. I might replace some of the smaller ANL fuses in the diagram with in-line breakers.

Any feedback is greatly appreciated!


  • mcgivormcgivor Posts: 2,219Solar Expert ✭✭✭✭✭
    The fues/breaker for the panels in series should be the maximum fuse size recommended on the reverse of the panels, typically 15A for that size, but if 20A that's fine, did you use the Morningstar string calculator to make sure the configuration is good for local temperature extremes, worth a check. Use non automotive  breakers instead  of fuses, easy to trouble shoot more reliable and if blown can be turned back on. Otherwise the layout looks good.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 

  • DaveDave Posts: 28Registered Users ✭✭
    I'm curious what your panels' max voltage rating is?
    12 * 300 W (10 fixed rooftop, 2 movable pole mount), Morningstar Tristar MPPT 60, Magnum 4448 PAE, 16 Crown CR-235 6V in two parallel sets of 8 (470 Ah)
  • MysteriousFoundationMysteriousFoundation Posts: 22Registered Users ✭✭
    edited July 28 #4
    Yes, I used the MorningStar Calculator. That's the link with all the relevant values. I don't have the panels on hand yet, so I can't look at the back, and the spec sheet online doesn't appear to mention fusing. The Isc is 9.65A, and if I add 25% for unusual solar situations, then it comes to about 12A. A 15A fuse sounds appropriate. I'm not sure why I put down 20.

    What breakers do you recommend? Someone recommended MidNite Solar breakers and box in a previous thread, but it seemed like overkill to me for my RV. Is that along the lines of what you were thinking?

    I've been looking at the offerings from Blue Sea Systems. They're really pricey, and I wound need several of them. There are cheaper ones from random Chinese brands like ZOOKOTO. I don't know how reliable they are.

    I'm curious what your panels' max voltage rating is
    That's a very good question. It's something I never even considered. I guess I figured if the controller can handle the voltage then the panels themselves could, too. Wait, is that even what you're asking? How much voltage the panels themselves can take in series?

    I don't see the answer on the spec sheet on Amazon. Going to the company website doesn't show any more information. What's the typical limit for panels such as these?
  • mcgivormcgivor Posts: 2,219Solar Expert ✭✭✭✭✭
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 

  • MysteriousFoundationMysteriousFoundation Posts: 22Registered Users ✭✭
    Is there any reason to believe these five panel wouldn't be able to handle upward of 90V when in series?

    Everything I can find about the voltage limit of panels comes down to the legal limit of 600V in some places, and the voltage limit of controllers. I can't find anything about the voltage limit of panels themselves. Considering the other limits I've found, I have a hard time believing there will be a problem, but please let me know if I should contact the manufacturer.
  • EstragonEstragon Posts: 2,850Registered Users ✭✭✭✭✭
    IMHO, 12v nominal panels aren't generally used in larger series strings, so I wouldn't count on them being designed for similar voltages as larger panels. They can probably handle 90v, but I'd check to be certain.
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • MysteriousFoundationMysteriousFoundation Posts: 22Registered Users ✭✭
    edited August 2 #8
    The company finally got back to me. They said, "Normally about 10 175w panels can be wired in series.The voltage is about 100 volt."

    That doesn't make any sense to me. The panels have a Vmp of 19V. How can ten in series only be 100V? If she got the voltage wrong, but 10 in series is still safe, then that's good news for me. If she got the voltage right, then that's worrisome, because even with temps only as low as 60°F, the MorningStar calculator says five panels would yield up to 120V.

    I replied to ask for a clarification. We'll see what she says.

  • BB.BB. Posts: 27,907Super Moderators, Administrators admin
    In General, you would wire up 5x Vmp~190 volt panels in series for 95 VDC Vmp-std (standard test conditions). And you would wire a second string in parallel for the other 5x panels (10 panels total).

    For 1-2 parallel strings, you do not need a separate fuse/breaker per string, but it can be nice for debugging (turn off array when working on system, turn off one string to see if the other is working correctly, etc.).

    How many panels in series and what size fuse/breaker to use--That is up to the vendor to tell you (and usually comes with UL/CSA/ETL "Listing". 15 Amp should be OK (need fuse/breaker rated for ~150 VDC)--20 amp is rated for some similar panels, and would have less of a chance at false tripping--If the 15 amp devices trip, then you may have to go to 20 amp devices--Although, many less expensive fuses/breaker have been known to trip at much less than rated current. The panels themselves, it is a guess. Voc-cold~150 VDC rated should be nominal for them--But they do not have to design for that (Voc-std is ~22 VDC per panel).

    Unless you live in a region where it gets way below freezing, the Voc-cold (voltage open circuit cold) should still be below ~140 VDC.

    If it does get well below freezing, then you have to check the Vpanel input of the solar charge controller is not lower than Voc-cold-array for your region.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • MysteriousFoundationMysteriousFoundation Posts: 22Registered Users ✭✭
    Thanks, BB.

    I just got a response from someone more knowledgeable:
    Our mistake with the voltages.

    Technically the maximum voltage is 600v, that's also the rating on the wire.  But to keep it safe i would say 500v will be an ideal number.

    Besides almost all the inverters dont need any voltage above 500v.

    For 5pcs in series, the voltage will be around 100v on open circuit, which is under the 150v allowance on Morningstar MPPT controller

    Perfect! Now I feel safe ordering everything.
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