Sanyo HIT N 215W panels in 48v off grid system?

osirisforward
osirisforward Registered Users Posts: 5 ✭
in Off Grid Solar & Battery Systems #1
Hi, I'm new to this forum so if this has been covered before my apologies. I have a 48v Rolls battery system with 4ks25 batteries 1300 a/h (20 hr rate), an Outback dual 3500w inverter panel and I want to upgrade my PV panels to some 215w Sanyo HIT N panels that I can get at a pretty good price. If I wire two panels that have a 51.6 VOC in series, into an Outback MX controller will this provide a proper voltage for charging these big batteries? Also considering a Midnite Classic 200 and then I could wire three panels in series? I get some cold winter temps so want to have lots of headroom for the -40+ temps.

All help much appreciated!
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: Sanyo HIT N 215W panels in 48v off grid system?

    More or less, the minimum Vmp voltage for charging a 48 volt battery bank should be around ~70 VDC minimum.

    Flooded cell lead acid batteries should be charged around 58-62 VDC, and you need to allow for the fact that solar panels, when they get hot, have their output voltage depressed. As well as to allow for voltage drop in wiring and across the charge controller.

    So, for a MPPT and PWM type charge controller--this works out to ~70 VDC minimum Vmp for panel rating (i.e., ~17.5 volts for charging a 12 volt battery bank).

    With MPPT type charge controllers, you can, for the typical 150 VDC maximum Vpanel input panel, run upwards of 100 VDC Vmp (STC Rating) for the solar array. The MPPT controller will efficiently down convert the high voltage/low current from the solar array to the lower voltage/higher current required for charging the battery bank (sort of like the DC equivalent of a variable AC transformer).

    Knowing your minimum and maximum ambient temperatures for your area will help nail down the actual supported Vmp-array rating for your system.

    For your Sanyo HIT 215 watt panels, 2 panels in series, with minimum temperature of -40C to max ambient temperature of +35C gives (using the Xantrex/Schneider string sizing tool):
    2 Modules 122 Vdc 71 Vdc
    So, it looks like that is the ideal setup for your system.

    For the Classic Controller--what is the maximum Vpanel input version you are looking at? Three panels in series would give you Voc-cold of ~183 VDC maximum at -40C.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • osirisforward
    osirisforward Registered Users Posts: 5 ✭
    #3
    Re: Sanyo HIT N 215W panels in 48v off grid system?

    Hi Bill, thanks for your reply. The maximum V panel input version I'd be looking at is the Classic 200. I think that would allow me to string three panels together but maybe there's no advantage to doing it this way -- could just stick with the MX?

    So if I understand this correctly as long as I have an mppt controller and have two or more panels strung together I will get enough voltage to satisfy the 48v battery?

    I'm in northern BC and can get brief periods of -40 in January and brief periods of 90 degrees in summer.

    ----
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #4
    Re: Sanyo HIT N 215W panels in 48v off grid system?

    For those panels on a 48 volt battery bank--yes.

    The new Classic has other new features too that may be nice for you.

    By the way, are you looking at the older MX Outback product--or the current production FM product line?

    Also, from our host:
    Solar Controller EMI and RF Noise Note:

    We have had some reports of high RF interference (EMI) noise being radiated by the Outback Flexmax controllers. If your solar system is being used for any type of communications system, such as cell phone relay, ham radio, or similar then we recommend that you use the Xantrex XW-SCC or the Morningstar TS-MPPT charge controllers. Those are the currently the only solar charge controllers certified to FCC Class B, Part 15. This noise may also affect AM radio and TV reception.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • osirisforward
    osirisforward Registered Users Posts: 5 ✭
    #5
    Re: Sanyo HIT N 215W panels in 48v off grid system?

    Hi Bill, yes I have the MX Outback controller in the system right now but interested in the upgrading to the Classic 200. Aside from the higher VOC capability and some other neat features I don't think there is any improvement in performance though -- is there?

    BB. wrote: »
    For those panels on a 48 volt battery bank--yes.

    The new Classic has other new features too that may be nice for you.

    By the way, are you looking at the older MX Outback product--or the current production FM product line?

    Also, from our host:



    -Bill
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #6
    Re: Sanyo HIT N 215W panels in 48v off grid system?

    I am not the person to answer that question. I do not use or test off grid controllers.

    The newer controllers are probably more efficient, but not worth buying a new one if you already have the mx.

    Are you going to keep the existing solar array too?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • osirisforward
    osirisforward Registered Users Posts: 5 ✭
    #7
    Re: Sanyo HIT N 215W panels in 48v off grid system?

    Naw I'm cashing in the old panels so I can stretch the budget for the new ones :D
    BB. wrote: »
    I am not the person to answer that question. I do not use or test off grid controllers.

    The newer controllers are probably more efficient, but not worth buying a new one if you already have the mx.

    Are you going to keep the existing solar array too?

    -Bill
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  • osirisforward
    osirisforward Registered Users Posts: 5 ✭
    #8
    Re: Sanyo HIT N 215W panels in 48v off grid system?

    Actually I have been thinking about this .. the old panels are some Isofoton 150's and I've been told that I could conceivably marry the Sanyo's & Isofotons even though they have different electrical characteristics - because of the mppt controller. The strategy is to wire one 150 to one 215. Have you heard of this?
    osirisforward wrote: »
    Naw I'm cashing in the old panels so I can stretch the budget for the new ones :D
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #9
    Re: Sanyo HIT N 215W panels in 48v off grid system?

    It depends... Basically you need to match Vmp/Imp for parallel/series connections.

    For example assuming your Isofoton 150 panels:
    Imp = 4.35 Amps
    Vmp = 34.6 Volts

    And the Sanyo 215 Watt HIT modules are:
    Imp = 5.13 Amps
    Vmp = 42.0 Volts

    This is a tough one to mix/match on one controller... Basically for series connections, Imp should be within for 10%--And for parallel connections, Vmp should match within 10% too...

    The Imp is more like 5.13/4.35 = 1.18 or 18% difference--A bit much. You may loose a fair amount of power overall.

    And trying to match Vmp -- 42/34.6 = 1.21 or 21% difference...

    And, I do not see any way of mixing series/parallel connections of these panels on one standard input voltage MPPT controller...

    However, it is perfectly OK if you leave the current Outback MX controller + Isofoton panels connected to your battery bank and get a second MPPT controller for the new panels--and connect it in parallel with the existing controller to your battery bank.

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