Looking for the right combination for grid tie.

FL SUNFL SUN Solar Expert Posts: 94 ✭✭✭✭
I need some advice on choosing the right modules for a 5 kw GT package using Evergreen ES-A series modules, and a Xantrex 5.0 GT inverter.

The roof will fit 24 of these Evergreen modules very nicely. Since the modules from 190 to 205 watts are the same physical size, I want to get as many watts as I can to fit the roof and match the inverter to maximize output.

Running the string sizing program for the Xantrex 5.0 GT, the wattage is OK (ES-A-205), but the voltage for 24 panels is in the 583 Voc range for 40 degrees F. The coldest we would get here is 50 degrees F with direct sun, and that would be very rare. As I plug in the lower wattage panels (sizing program) down to 190 watt panels, the Voc reduces each time slightly, but of course the wattage does too.

Since I am trying to utilize the inverter's capability, and gain the most solar energy harvest, what modules and number would you choose given the inverter, and Voc issue?

Comments

  • Solar GuppySolar Guppy Solar Expert Posts: 1,962 ✭✭✭
    Re: Looking for the right combination for grid tie.

    You will be fine with 24 12V nominal panels in series

    VOC values are for 1000wmsq , or solar noon, best case. If you look at any solar panels VOC vs Irradiance, it drops with the Irradiance ... ball park, at 100 wmsq its about 4 volts lower than 1000wmsq for a 12V panel

    So for 24 in series, it will be 80-100V lower than the online tools show for early morning sun. The Online tools don't scale for irradiance, they just use the peak 1000 watt-meter-squared value

    A GT5.0 is a PERFECT match for 24 ES-205's ... the inverter limits at @ 5200 watts DC, so you can handle even edge of cloud well with little if any power limit

    Now, if your running Solar Noon open circuit in the Artic, that's another issue, but here in Floirda, you voltages will be be fine.

    I have run 4+ years 20, 18V modules in series in to a GT3.3 ... I think the highest I have ever seen was 550V, on a 28 degree morning ..

    Also ran two 24 panel 12V modules in a single series string into Sunnyboys for a year at my old home ( and for the Home Power Article ) ... voltages we in the low 400's open circut
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Looking for the right combination for grid tie.

    careful sg he said 190w and up evergreens so several strings are in order.
  • Solar GuppySolar Guppy Solar Expert Posts: 1,962 ✭✭✭
    Re: Looking for the right combination for grid tie.

    Hi Neil,

    They are all the 12V panels ... the difference in the wattage is slightly higher VMP values. The 190-210 are all the same model

    He is looking at a single 24 panel string, for Florida, 100% safe
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Looking for the right combination for grid tie.

    ok. didn't you call them 18v pvs, which is more accurate for their higher vmps, but isn't a popular voltage for batteries?
  • FL SUNFL SUN Solar Expert Posts: 94 ✭✭✭✭
    Re: Looking for the right combination for grid tie.

    Yes, to re-iterate, these are the ES-A series which is the lower voltage panel.

    Since Evergreen has stopped production of the higher voltage model (ES-190-SL), I am forced to work with many more panels in a string. (Begrudgingly). I wonder why they quit that line?

    Thank you SG for that info. Just what I needed to hear. The (24) 205's will be what I choose. It will be going on my house by the way. Do you have a link to your array output monitoring? I would be very interested in seeing your array's performance.

    Thanks again for the input.

    John
  • Solar GuppySolar Guppy Solar Expert Posts: 1,962 ✭✭✭
    Re: Looking for the right combination for grid tie.

    Solar panels for legacy reasons are named based on what you would hook them up to for direct or pwm charging

    12V ( 16-18vmp , 20-22Voc )
    18V ( 24-27vmp , 30-33Voc )
    24V ( 32-36Vmp, 40-44Voc )

    This is a good example of what the current solar panels on the market are. The Evergreens which I have 70 on my roof now are either 12V or 18V module. The older 170-190's are 18V and the newer ( A's ) are all 12V modules

    The poster was asking about the 205 watts "A" module, that is just about identical to the 200 watts "A" I just installed.

    There are of course other panels ( Sanyo's come to mind ) as well as Asi panels that have voltage parameters that don't fall into the common 12/18/24V range ...

    Hopefully this is clearer than mud!
  • FL SUNFL SUN Solar Expert Posts: 94 ✭✭✭✭
    Re: Looking for the right combination for grid tie.

    Thanks again for the replies. I do understand about the nominal panel voltage. Your explanation made it clear as a bell.

    Learn more and more every day.
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