Integrating Different Kinds of Panels

romsolar
romsolar Registered Users Posts: 1
in Advanced Solar Electric Technical Forum #1
Chronar panels and windynation panels

I need some good advise how to effectively integrate the two different panels into 1 system. I have blocking diodes on both sets of panels now - actually there are 2 chronar panels and 1 windynation panel. Technics

Windynation 30w 20v open - this single panel comes with blocking diodes
Chronar. 14w 17.7v open each -- added together in // ---> 28w 17.7v open - no diodes

Initially without blocking diodes on chonar panels and connected in parallel with the other, the battery went into low voltage after 1-2 days, and without chronar panels the battery has not been in a low voltage state since.

Observation - the chronar panels are not so good in shade conditions or low light conditions as the windynation panel is; that is they have lower voltage for the same light condition.

Question-

what is the resutant voltage when the two different voltages are added in parallel?
Is there another way to connect all panels together other than the obvious parallel?
Will the blocking diodes on the chronar panels eliminate the low voltage battery condition?

Has anyone out there solved this problem?
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Comments

  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #2
    Re: Integrating Different Kinds of Panels

    You did not say what kind of Charge Controller (CC) you are using. The biggest difference will be between an MPPT and a PWM CC.
    For an MPPT CC the panels or panel strings that you parallel should be within ~5% of each other in Vmp. Often that means that the Voc will be within 5% as well, but if the cell type is very different (crystaline versus amorphouse, or Si versus other chemistry) the ratio between the two (Voc and Vmp) can vary.
    Anyway, the difference between 17.7 and 20 is over 10% so the results would not be ideal, but still better than only using one kind of pane.
    If you have a PWM CC or are not using a CC at all, then you will not lose anything by paralleling the two kinds of panels, since the output of both will be pulled down close to the battery voltage (~14V).
    what is the resutant voltage when the two different voltages are added in parallel?
    Is there another way to connect all panels together other than the obvious parallel?
    Will the blocking diodes on the chronar panels eliminate the low voltage battery condition?
    1. More than the lower panel voltage but higher than the lower voltage (when talking about working voltage, not open circuit voltage.)
    2. You could connect the in series (bad idea, since the current values are so different). Or you could connect the two Chronar in parallel and put them in series with the windynation (if and only if you have an MPPT type CC which can handle a voltage of 40V or more. (The voltages will be higher than you list on a really cold day.)
    3. If the reason that the battery voltage went low is back discharge through the Windynation panel during the night, then getting a blocking diode to use with it should fix the problem. It will also drop the output voltage of that panel by between .2 and .8 volts depending on the type and size diode you get.

    You did not say what type and size battery you had either. A 12V lead acid (not GEL) battery with a capacity of 30Ah or more would not necessarily need a charge controller, depending on how much load you put on the battery each day. But you might end up having to add water a lot if your load is small enough.
    Bottom line, a small inexpensive, but reliable CC might solve all of your problems, since it would remove the need for separate blocking diodes.
    SMA SB 3000, old BP panels.
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