alexis1988: "24 volt" solar panels and correct charge controller questions

This discussion was created from comments split from: Matching my panel with a charge controller.


  • alexis1988alexis1988 Registered Users Posts: 9 ✭✭
    Hello People. I,m new here, i just want to make a question about the system that i want to get. Here is the panels that I'm getting. 3 panels of 345w. With VMP 37.35. Imp. 9.237a. I guest these are 24v panels...right? And im planing to put them im parallel. And four battery to Serie. At 24v. Which MPPT charge controller will support or i need? 40amp controller or 60a?
  • BB.BB. Super Moderators, Administrators Posts: 28,315 admin
    Hi Alexis,

    I have moved your question to your own thread... That way we can keep the Q&A focused on your issues.

    Yes, you are correct Vmp~35-40 volts are "24 volt" panels for charging a 24 volt battery bank directly (typically with PWM charge controller).

    With an MPPT charge controller, you really want Vmp-array > ~40 VDC to have the MPPT operate optimally. Vmp-array for a MPPT controller on a 24 volt battery bank would work very nicely around 60 Volts Vmp-array... Depending on the charge controller, roughly Vmp-array of ~100 VDC maximum (for very cold climates with a higher end 140-150 VDC maximum Vpanel input MPPT charge controller).

    The "issue" with the Vmp~37 volt panels, is that 2x in series will work fine... However, 3x in series may be too high of voltage (if you live in/visit very cold locations). Matching your array to the charge controller+battery bank is kind of a pain.

    Do you have a charge controller brand you are interested in? Many companies have a website where you can input the solar panels+battery bank+temperatures to make sure that all works well together.

    Can you tell us a bit about your battery bank (type of battery, voltage, AH rating, etc.)? And about your loads (Amps*Hours, Watt*Hours per day, etc.)? Where the system will be located?

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • alexis1988alexis1988 Registered Users Posts: 9 ✭✭
    Ok. Now. As u said it it would need more vmp. To work with Mppt to charge 24bank battery. But if i use the battery as 12v in parallel(3 batteries 12v) of 105 ah each. The batteries are Marine deep cycle. Will the panels work with the LASolarEpic 40A MPPT Solar Charge Controller 100V input Tracer A Series 4210A. And a 2000w Inverter. Do you think the 24v panels will work with the MPPT and charge 3 batteries in parallel as 12v?
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