Mixing Panels with FM80

firefly
firefly Solar Expert Posts: 66 ✭✭
in Off Grid Solar & Battery Systems #1
Would like to know if this is a possible configuration. Right now the array is 6 Solar World 240 watt/poly, 60 cell with a Blue Sky 50 charge controller. The owner wants to add 2 Kyocera 210 watt, 54 cell to the array and switch to a Outback FM80. Array would be wired series/parallel.

Spec's are. SW240 watt
Voc 37.2
Vmp 30.2
Ics 8.44
Imp 7.96

Kyocera 210 watt
Voc 33.2
Vmp 26.6
Ics 8.58
Imp 7.90

Any suggestions would be appreciated.
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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: Mixing Panels with FM80

    What is the battery bank voltage?

    In any case, the panels are "close enough" that you can intermix series or parallel connections and not cause a lot of issues...

    Adding the panels in series would have been better (Imp is much closer match)--However, because he has 6 Solar World and only 2 Kyoceras.

    Pending knowing the battery bank configuration, I would probably mix them as:
    • SW+SW
    • SW+SW
    • SW+Ky
    • SW+Ky
    Mixing the SW+Ky will keep their Vmp-array closer to the SW+SW Vmp vs running the two Ky+Ky in one series string.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: Mixing Panels with FM80

    From the looks of the panel specs you could put the Kyocera's in series with the Solar World panels, as the Imp is very close: 7.90 and 7.96
    Parallel connecting is a bit more of a problem as the Vmp's are almost 10% apart per panel.

    If you mix 'em up it might work:
    Two strings of 2 Solar World (Vmp 60.4, Imp 7.96)
    Two strings of 1 Solar World and 1 Kyocera (Vmp 56.8, Imp 7.90)

    That's about 6% difference in Vmp (with the Kyoceras on one string the difference in Vmp would be 11%).

    The FM80 could handle that much panel on a 24 or 48 Volt system. The FM60 could probably do it on 24 Volt too, what with the panel efficiency loss and all.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #4
    Re: Mixing Panels with FM80

    Two panels up would not support a 48 volt battery bank (Vmp>70 volts recommended; Vmp>60 volts required at ambient temperatures).

    Your only other combination with the 6+2 panels you can reasonably use at high voltage is 4 series + 2 parallel strings--but if this is a climate with cool to cold winters, Voc will exceed the controller maximum input voltage rating (typically 150 VDC).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #5
    Re: Mixing Panels with FM80

    caution

    an sb50 is only rated to 57v tops and there was scuttlebutt that some failed prior to that point meaning the pvs cannot go in series with the sb50. you need another controller, fm60 is fine, as the 6 solarworlds are pushing the sb50 to it's current limit. in getting another controller the 6 solarworlds can go on the fm60 and you could still utilize the sb50 with the 2 kyoceras in parallel and thus taking out any differences in the pvs as a factor by making these 2 separate systems with a common battery bank.. this would also allow for further expansion later.
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  • snuffy
    snuffy Solar Expert Posts: 72 ✭✭✭✭
    #6
    Re: Mixing Panels with FM80

    Why not go with a Midnight solar Classic and 2 strings of 3 SW's and 1 Kyocera in each string? It will handle the higher Voc.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
    Re: Mixing Panels with FM80
    snuffy wrote: »
    Why not go with a Midnight solar Classic and 2 strings of 3 SW's and 1 Kyocera in each string? It will handle the higher Voc.

    On the whole, I like snuffy's solution the best. Even though the Midnight Classic is pricey compared to the FM80 it would handily solve the problem - especially for a 48 Volt system. :D
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  • snuffy
    snuffy Solar Expert Posts: 72 ✭✭✭✭
    #8
    Re: Mixing Panels with FM80
    Cariboocoot wrote: »
    Even though the Midnight Classic is pricey compared to the FM80:D

    Even if we count the losses incurred by using an unbalanced solar array?
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  • firefly
    firefly Solar Expert Posts: 66 ✭✭
    #9
    Re: Mixing Panels with FM80

    The battery bank is 24 volt. Great response, very much appreciated, thanks to all.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
    Re: Mixing Panels with FM80
    snuffy wrote: »
    Even if we count the losses incurred by using an unbalanced solar array?

    In your proposed configuration, two strings of three Solar World and one Kyocera each, the array is balanced. The series wiring is dependent on Imp, which is almost identical between the two panels. The Vmp per string is then what matters for the parallel connection. In this case it would be exactly the same on the two strings.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #11
    Re: Mixing Panels with FM80

    with a 24v battery bank then you have a problem utilizing that sb50 as the sw pvs would still be at the limit for the current capability of the cc and placing the kc210s in series would put the sb50 too close to its max voltage. i will agree with snuffy as the classic would fit this application very well with one controller, but higher losses are incurred as a result of the high input to output voltage ratio. keep in mind that the 2 strings would be pushing the voltage around the max for the fm series, but not for the classic 200. smaller strings that are slightly off from one another is a possibility that is viable with the fm series or the classic. smaller in/out ratio losses can be offset with higher pv balance losses. imo he'll need to accept some losses in order to use 1 cc. 2 controllers could wipe that loss, but at a much higher cost and the sb50 is not recommended by me as the 2nd controller in this case. if going with 1 fm series cc it would need to be the fm80 as the fm60 would be borderline and a classic 150 would also suit here.

    it seems much consideration will be needed as to what this guy will want to do. in buying and using only 1 cc, the classic would allow for more expandability as it is capable of more current whereas the fm80 would be at closer to the nec output limit of 64a for the fm80, but both would work with more than 2 strings in an unbalanced arrangement, but only the classic will safely allow for 2 hv strings with higher i/o losses.

    tough call, but the sb50 is out of the equation.
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  • snuffy
    snuffy Solar Expert Posts: 72 ✭✭✭✭
    #12
    Re: Mixing Panels with FM80
    Cariboocoot wrote: »
    In your proposed configuration, two strings of three Solar World and one Kyocera each, the array is balanced. The series wiring is dependent on Imp, which is almost identical between the two panels. The Vmp per string is then what matters for the parallel connection. In this case it would be exactly the same on the two strings.

    I was referring to this arrangement as the unbalanced one:
    "If you mix 'em up it might work:
    Two strings of 2 Solar World (Vmp 60.4, Imp 7.96)
    Two strings of 1 Solar World and 1 Kyocera (Vmp 56.8, Imp 7.90)"
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #13
    Re: Mixing Panels with FM80
    snuffy wrote: »
    I was referring to this arrangement as the unbalanced one:
    "If you mix 'em up it might work:
    Two strings of 2 Solar World (Vmp 60.4, Imp 7.96)
    Two strings of 1 Solar World and 1 Kyocera (Vmp 56.8, Imp 7.90)"

    That was my concept for use with the FM 80. It's only slightly out-of-whack with about 6% Vmp difference between the strings.

    Your way is better as there is no imbalance between the strings. :D

    Might need the Classic 200, though, because the Voc of that configuration is very near 150 Volts at 145; a spot of cold weather could put it over.
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