Marine Application - 48v controller needed.

mixman
mixman Registered Users Posts: 4
in Off Grid Solar & Battery Systems #1
I have a 230 watt (PTC 209.5W) 48-volt panel on my boat. I need to connect it to a 12v bank made up of 3 group 31 (105ah each) AGM batteries wired in parallel for charging and loads. I have found the following controllers that I think will work:

MorningStar TriStar 45 MPPT
Blue Sky SB3048 MPPT
MorningStar ProStar 15 – 48V
Xantrex(Schneider Electric) C40

I am looking for advice and will certainly consider other models. My main question is should I get an MPPT controller or not? Will I get enough of a benefit from it considering the usage is almost all warm-weather? I'm leaning towards the MorningStart ProStar 15-48, but they caution against marine installations due to the harsh environment. Where I would be mounting the controller would be a very protected and dry area.

Kurt
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #2
    Re: Marine Application - 48v controller needed.
    mixman wrote: »
    I have a 230 watt (PTC 209.5W) 48-volt panel on my boat. I need to connect it to 3 group 31 (105ah each) AGM batteries for charging and loads. I have found the following controllers that I think will work:

    MorningStar TriStar 45 MPPT
    Blue Sky SB3048 MPPT
    MorningStar ProStar 15 – 48V
    Xantrex(Schneider Electric) C40

    I am looking for advice and will certainly consider other models. My main question is should I get an MPPT controller or not? Will I get enough of a benefit from it considering the usage is almost all warm-weather? I'm leaning towards the MorningStart ProStar 15-48, but they caution against marine installations due to the harsh environment. Where I would be mounting the controller would be a very protected and dry area.

    Kurt

    You did not specify whether your batteries are wired in parallel or series. If in parallel, then the 48 volt panel output into a PWM controller with 12 volt charging will waste 2/3 or more of your panel power. On the other hand, if you are making a 36 volt series battery bank and have a PWM CC that is designed for that battery voltage, an MPPT CC will not be getting you all that much greater efficiency.
    SMA SB 3000, old BP panels.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: Marine Application - 48v controller needed.

    Welcome to the forum, Kurt.

    Might as well ask the question first: what are the specs on that panel? Do you have a make/model?

    It makes a difference as some of the charge controller choices are PWM (like the C40) and won't work properly on a system unless the panel has the right Vmp. Whereas an MPPT controller can take "too high" of a Vmp and down-convert it for proper charge Voltage. A 48 Volt system needs a Vmp around 70, which is rather unusual in a panel.

    You are correct that in warm temps you won't see any of the cold weather benefit on MPPT, but you might need it for getting the Voltage right as per above. If the panel Vmp is too low, no charge controller can make up for that.

    Three AGM batteries? That's rather unusual for 48 Volts too. Do you have the Voltage specs on those as well? If they are 48 Volt, then you'd have 315 Amp hours @ 48 Volts. One 209 Watt panel will not do much towards charging that much battery.
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  • mixman
    mixman Registered Users Posts: 4
    #4
    Re: Marine Application - 48v controller needed.

    I guess I do too much posting on boating forums :-) There we all assume a bank is 12v unless someone specifies 24v. I have edited my OP to state that the bank is wired in parallel and is thus a 315ah 12v bank. The panel specs are:

    http://www.solardesigntool.com/components/module-panel-solar/Sunpower/SPR-230-WHT-U/specification-data-sheet.html

    STC Power Rating 230W
    PTC Power Rating 209.5W 1
    STC Power per unit of area 17.2W/ft2 (184.8W/m2)
    Peak Efficiency 18.5%
    Power Tolerances -5%/+5%
    Number of Cells 72
    Nominal Voltage not applicable
    Imp 5.61A
    Vmp 41V
    Isc 5.99A
    Voc 48.7V
    NOCT 45°C
    Temp. Coefficient of Power -0.38%/C
    Temp. Coefficient of Voltage -0.133V/C
    Series Fuse Rating 20A
    Maximum System Voltage 600V
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #5
    Re: Marine Application - 48v controller needed.
    mixman wrote: »
    I guess I do too much posting on boating forums :-) There we all assume a bank is 12v unless someone specifies 24v. I have edited my OP to state that the bank is wired in parallel and is thus a 315ah 12v bank. The panel specs are

    STC Power Rating 230W
    PTC Power Rating 209.5W 1

    Imp 5.61A
    Vmp 41V
    Isc 5.99A
    Voc 48.7V
    NOCT 45°C
    Temp. Coefficient of Power -0.38%/C
    Temp. Coefficient of Voltage -0.133V/C
    Series Fuse Rating 20A
    Maximum System Voltage 600V

    1. With a Vmp of 41 volts from the panel, you really want to use an MPPT controller to get the most power into the battery. The MPPT controller will convert the 41 volts at 5.6 amps to ~15 volts at ~13 amps. Well worth the price if you want to charge the batteries quickly.

    2. Speaking of which, for 315 AH of 12 volt battery, you should have something like 300+ rated watts of panel to charge the batteries properly independent of how much your daily load will be. You want to be able to get the charging current up to 15 amps for FLA batteries or as much as 60 amps for AGM, even if it is for a shorter time. But the other sizing factor for your panels is what your power consumption from the batteries will be over the course of a day.

    3. Depending on the type of boat you have, finding a good unshaded mounting locations for the panel(s) may be difficult and may also justify adding more panel wattage in the form of at least one more panel. The panels should be in parallel so that each panel can still deliver its full output if the other is partially shaded.
    SMA SB 3000, old BP panels.
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  • mixman
    mixman Registered Users Posts: 4
    #6
    Re: Marine Application - 48v controller needed.
    inetdog wrote: »
    1. With a Vmp of 41 volts from the panel, you really want to use an MPPT controller to get the most power into the battery. The MPPT controller will convert the 41 volts at 5.6 amps to ~15 volts at ~13 amps. Well worth the price if you want to charge the batteries quickly.
    Wow, that will most certainly make me consider an MPPT controller. BIG difference! Thanks.
    2. Speaking of which, for 315 AH of 12 volt battery, you should have something like 300+ rated watts of panel to charge the batteries properly independent of how much your daily load will be. You want to be able to get the charging current up to 15 amps for FLA batteries or as much as 60 amps for AGM, even if it is for a shorter time. But the other sizing factor for your panels is what your power consumption from the batteries will be over the course of a day.
    I am ashamed to admit it, but when buying the mounts for the panel I went with that vendor's recommendation of a crappy MPPT controller. The second one is dead and the warranty support sucks. However, I'm very happy with that this single panel will do for me. Our draw at anchor is low enough that it works. But we need to run our generator a bit every day anyway (hot water, water maker, ice maker) so we make up for lost amps.
    3. Depending on the type of boat you have, finding a good unshaded mounting locations for the panel(s) may be difficult and may also justify adding more panel wattage in the form of at least one more panel. The panels should be in parallel so that each panel can still deliver its full output if the other is partially shaded.

    It's a 30' power catamaran. I am limited on space for panels so for this boat at this time, it's just the one panel. But you're of course right. Enough panels could power a boat this size with no other power source needed. The only shade issue is my anchor light, which I can take down if it's an issue.
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  • mixman
    mixman Registered Users Posts: 4
    #7
    Re: Marine Application - 48v controller needed.

    Thanks for all the information. I went with a Morningstar SunSaver MPPT-15L. The rated Max PV Input is 200 and my panel is 209.5, but after speaking with Morningstar tech support (located less than an hour from me in Maryland, interestingly enough), they said 250 is actually the max. I'm looking forward to trying out this weekend.
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