Use DC optimizers with mismatch modules?

ssakamoto
ssakamoto Registered Users Posts: 1
in Advanced Solar Electric Technical Forum #1
I have seven SunPower E series PV modules, that are a mix of 305, 308, 310 and 327W modules. Would DC optimizers allow me to maximize the production of each module? Otherwise I believe the whole string would perform at the level of the lowest rated module, correct?
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #2
    Correct.
    SMA SB 3000, old BP panels.
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #3
    ssakamoto wrote: »
    I have seven SunPower E series PV modules, that are a mix of 305, 308, 310 and 327W modules. Would DC optimizers allow me to maximize the production of each module? Otherwise I believe the whole string would perform at the level of the lowest rated module, correct?

    Welcome to the forum,

    That is correct if the panels are all in series as a single string... Is that how they are connected? If they are all in parallel, that is not correct. Please tell us more about your system... grid tied? battery voltage? charge controller? etc

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    #4
    Those are most likely all 72 cell panels. Personally i wouldnt stress too much about it. Look at some scenarios and study the MPP issues if any that arise.
    For example two strings of 3 into a classic 150 at 24V. (OR 2 strings of 3 into 48V). Put the smaller ones in one string, the bigger in the second. 7 of course is an odd number, the only way to use all 7 is likely impractical, ie 7P, which is too much for any PWM controller, and barely enough voltage to run MPPT. Maybe Classic in legacy mode will work at 24V, if their Vmp is 36 or better. Likely as not it will be the current that varies in those panels, and the Vmp is similar? My gut sense is that the variance loss wont be much in the scheme of things.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


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  • SolarPowered
    SolarPowered Solar Expert Posts: 626 ✭✭✭
    #5
    The better harvest for the mismatch modules would be the ABB MICRO 0.3-I-OUTD

    ABB MICRO 0.3-I-OUTD accepts up to 65V, and 360 watts. The maximum power point tracking algorithm range using the spwr's would be better than using a DC optimizer/inverter combo which actually costs more money on the initial system costs VS the micro inverters and trunk cabling.

    As long as the VMP power tolerance is within -/+ 3% optimizers should work fine if you decide to stick with inverter/optimizer combo. I still believe Micro inverter harvests more, but that's just my singular professional opinion.
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