Running 60v (5 12v Panels) in series with Morningstar MPPT60?

wifii42
wifii42 Registered Users Posts: 2
in Off Grid Solar & Battery Systems #1
Greetings!

We have a solar off grid mountain top site used for Internet Communications that has been running great the last 5 months. The site owner already had purchased 10 100W panels and had them mounted at the site. When we originally set up the site we only hooked up 8 of the panels, 4 Panels in series and 4 panels in series parallelled to make a 48v system. It's working outstanding. Now we are considering adding some equipment up there and would like to use the 2 extra panels that are just sitting there unused.

Can the Morningstar handle a 60v system? The manual clearly states up to 48v but the max open circuit voltage is 150v. Even in best circumstances I can't see the voltage exceeding 110 - 120v. Our current setup hasn't exceeded 80v ever so far in voltage.

Yes, we could do a 2 * 5 bank setup at 24v but I'd rather not have to run higher guage wire back to the shack if we can avoid it

Our batteries are hooked up at 12v if that matters.

Thoughts?

Thanks!
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #2
    Re: Running 60v (5 12v Panels) in series with Morningstar MPPT60?
    wifii42 wrote: »
    Greetings!

    We have a solar off grid mountain top site used for Internet Communications that has been running great the last 5 months. The site owner already had purchased 10 100W panels and had them mounted at the site. When we originally set up the site we only hooked up 8 of the panels, 4 Panels in series and 4 panels in series parallelled to make a 48v system. It's working outstanding. Now we are considering adding some equipment up there and would like to use the 2 extra panels that are just sitting there unused.

    Can the Morningstar handle a 60v system? The manual clearly states up to 48v but the max open circuit voltage is 150v. Even in best circumstances I can't see the voltage exceeding 110 - 120v. Our current setup hasn't exceeded 80v ever so far in voltage.

    Yes, we could do a 2 * 5 bank setup at 24v but I'd rather not have to run higher guage wire back to the shack if we can avoid it

    Our batteries are hooked up at 12v if that matters.

    Thoughts?

    Thanks!

    When the description says up to 48 volts, that is a reference to 48 volt battery banks! It does not refer to the input voltage from the panels.
    You can use any combination of panels whose series Voc is less than 150 volts. (Not the series Vmp.) It sounds like your 10 panels are nominally 12 volt, which means that their Vmp is probably around 18 volts and Voc is around 20 volts. Putting 5 of these in series should not be a problem.
    What you also need to look at, however, is whether the power available from the panels will lead to higher current at 12 volts than the Morningstar can handle.

    So, for 1000 watts of panel, an MPPT Charge Controller can deliver perhaps 950 watts to the batteries. At 12 volts, that would be 80 amps. Do you have a 60 amp or 80 amp CC?
    SMA SB 3000, old BP panels.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #3
    Re: Running 60v (5 12v Panels) in series with Morningstar MPPT60?

    The TS-MPPT-60 can handle up to 60 amps going into the battery bank, so if you changed you're battery bank (and inverter) from 12 to 24 volt, you could double the watts your charge controller would be capable of handling and dumping into your batteries. Thus it matters very much if you're battery bank is 12 or 24 volt. And of course for even higher power handling, go to a 48 volt battery bank, and of course matching inverter.
    If I had only known when I first got into Solar, just how big my system would eventually become, I most definitely would have gone with at least 24 volt. Unfortunately, financially, over the years I've painted myself into a 12 volt corner :(
    It may not be too late for you.
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  • Coach Dad
    Coach Dad Solar Expert Posts: 154 ✭✭
    #4
    Re: Running 60v (5 12v Panels) in series with Morningstar MPPT60?

    Have you tried Morningstar's string calculator?

    http://www.morningstarcorp.com/en/strings/calc.php

    Just enter the data off the label and the calculator will tell you how many you can use.
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  • wifii42
    wifii42 Registered Users Posts: 2
    #5
    Re: Running 60v (5 12v Panels) in series with Morningstar MPPT60?

    Very Informative! Thanks! Once we get some kind of DC-DC converter in place we will make the change to 24v batt and add the panels. Our equipment runs on 12v right now and is happy up to around 24v so we would need something to keep the peace when it's charging at 28ish volts :)
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