Boat install - SmartHarvest vs Tristar decision

Erinscot
Erinscot Registered Users Posts: 18 ✭✭
in Solar Beginners Corner #1
I am adding two 290w panels to power my 675AHr 12v bank. Yes, I have an alternator and shore power to help charging when needed.  I like the idea of running each panel through a 20a SmartHarvest controller (300w max), but I have come across a Tristar 45 MPPT that would be around the same price.  Having the two controllers would minimize any potential shading issues, and adds redundancy. The tristar is a proven unit, while the SmartHarvest is new and relatively unproven.  The run from panels to bank is around 30 feet.  Other than the additional wiring involved with running a pair of controllers, are there any other considerations I am missing?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #2
    No--It should not be a problem... If the two panels are run in parallel and facing the same direction (off the stern of the boat, for example), you really only need one controller (the MorningStar 45 amp MPPT).

    If they are facing different directions (such as left and right side of cabin), then a pair of MPPT controllers may be a better choice...

    If this is for a 12 volt battery bank, then each 290 Watt panel would need a 20 amp MPPT controller minimum.

    With a 30 foot wire run... you want to run the ~Vmp 30 volts of each panel the long distance and install the charge controller(s) next to the battery bank with short/heavy gauge wire (low voltage drop to battery bank).

    That is a fairly large 12 volt battery bank--And 580 Watts is not a large array for that size battery bank. How much power/energy do you plan on using per day--And will it all come from the solar array, or are you planning on using the genset too?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Erinscot
    Erinscot Registered Users Posts: 18 ✭✭
    #3
    The panels will be in a flat orientation on the top of the boat.  Yes, I was planning on having the controller (s) within a foot of the 4/0 going from the inverter to the bank.  

    With boats, available surface area for panels is a major obstacle.  This is why I am amazed with how many people continue to run 140w 12v panels when grid-tie panels are abundant, and MPPT has come down in price.

    We are primarily running AC fridge and freezer, along with lights with the bank.  The intention of this solar project is to minimize the amount of engine charging we well need at anchor.  We realize that going 100% solar will be next to impossible on the boat, but this will buy us time between engine charges.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #4
    Yep--Boats are not great solar panel platforms--Especially sail boats with extensive shading... Just a simple line (or shadow from line) across a panel can dramatically reduce its useful output.

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