Evergreen ES series

rrbvrrbv Registered Users Posts: 15
On the Evergreen panels the naws site says do not use for battery systems:
See below:

Evergreen ES-190 Solar Panel
For Grid Tie Systems
26.7 Volts @ 7.12 Amps
Not for 24 Volt battery


The Vmp seems ok for a mpp controller. Why not for battery systems?
I am using 12ea 95 Photowatt panels with a similar Vmp and a BSBP50 charge controller in an off-grid system that has been operating for several years, but would like to add panels and the PW panels are no longer available. The B grade evergreen 170,180 and 190 watt panels are pretty inexpensive.

Comments

  • System2System2 Posts: 6,290 admin
    Re: Evergreen ES series

    I would say that they mean it's not for charging 24 volt batteries, as the voltage is too low for that job, and not for 12 volt batteries without a MPPT controller, as the voltage is too high, therefore low amps, wasting power. However, with MPPT such as the MX-60 they would be perfect for a 12 volt battery system.
    Wayne
  • nigtomdawnigtomdaw Solar Expert Posts: 705
    Re: Evergreen ES series

    Would they not be OK if wired in series to over 53.4 volts then through a MX60 for 24 volt system. ? Or would this waste energy ?
  • BB.BB. Super Moderators Posts: 26,837 admin
    Re: Evergreen ES series

    Short answer no... This is one of the reasons that MPPT controllers are so neat... They are much more flexible and work to spec. over a wide range of conditions (and much better that "simple" PWM controller--for larger systems >~200-400 watts typically)...

    You just need to go through the calculations to make sure that min/max voltages and currents are within requirements (as seen on other threads here--not always a trivial exercise).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Evergreen ES series

    I think Bill means - - no, it would not be a waste of energy - - if you're using an MPPT controller.
    In series, charging 24 volt battery through an MX-60, they should be the cats meow :)
  • BB.BB. Super Moderators Posts: 26,837 admin
    Re: Evergreen ES series

    Maybe I should have invested a few more $$$ in my sentence... Wayne was much more eloquent than I. ;)

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rrbvrrbv Registered Users Posts: 15
    Re: Evergreen ES series

    I understand now. The Vmp drops to 23.3 at "normal" operating temperatures:

    Nominal Operating Cell
    Temperature Conditions (NOCT)4
    P m p (W) 129.0 136.7 140.1
    Vm p (V) 23.3 23.8 23.9
    I m p (A) 5.53 5.75 5.86
    Voc (V) 29.8 30.3 30.5
    Isc (A) 6.20 6.46 6.59
    TNOCT (ºC) 45.9 45.9 45.9
  • BB.BB. Super Moderators Posts: 26,837 admin
    Re: Evergreen ES series

    Actually, assuming a 95F day and temperature rise in still air, the Vmp could be down towards 21.5 volts DC for that panel...

    Xantrex (array sizing calculator) appears to assume, roughly, a 40C (73F) rise on a hot day--and from my measurements of operating voltage for my array--I would have to guess they are pretty close. They predicted my operating voltage on a hot day to within a 0.5 volt...

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