24 vdc marine system

We have a 24 vdc system on the boat and want to make up a solar system using 2 panels on a pole to supply our battery bank.
How does this differ from a 12 volt system and what do I need.
All help appreciated.


  • BB.BB. Super Moderators, Administrators Posts: 30,946 admin
    Re: 24 vdc marine system

    Not a whole lot of difference... For example, instead of using 2x "12 volt" panels in parallel (add current, keep voltage the same), you would use the same 2x "12 volt" panels in series (doubles voltage, keeps current the same).

    For a small system, there is a nice MorningStar MPPT controller--it can be configured for either 12 or 24 volt systems (200 watts of solar panels at 12v, 400 watts of solar panels at 24 volts).

    Morningstar SunSaver MPPT Solar Charge Controller

    Otherwise, you can use any of the small PWM charge controllers (that support 24 VDC and your battery type, flooded cell, AGM, etc.).

    Just make sure that you don't get a very nice Outback or Xantrex 60 amp MPPT controller when you only have 10 amps of panels--it is a waste of money and power.

    Depending on where you are at (hot/cold weather, amount of sun, is the is a power boat or sail boat--with lots of shade, at dock or anchored out--boat twists in wind)--there are a lot of variables that make solar on a boat a little bit iffy at times (OK for trickle charging a battery bank, but not a whole lot of extra power to run a sailboat at sea, or keeping a bilge pump running in a leaky boat).

    Depending on the size of your battery bank--getting a remote Battery Temperature Sensor is a good idea to insure the solar charge controller properly charges your batteries (the larger the solar panels vs battery bank, the more important a remote BTS is).

    As aways, seal wiring and access holes against water leaks (especially if salt water). Try to get conformal coated circuit boards (or potted controllers) to help avoid problems with moisture. Also make sure you are using appropriate wire gauge and fusing/breakers to prevent shorts becoming fires.

    And, if you can, use glass mono or poly crystalline solar panels--unless you need something more impact resistant. Then look at a good quality UniSolar brand panel (still mounted in a flat frame). I would recommend against any of the "flexible" solar panels--they typically don't last long (6 months or so +/-).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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