My Enphase system how many KWH will it make?

Can anyone help me figure out what My new system will produce??

14 Sharp NE 165u5 panels
4 Canadian Solar 230w panels
Roof mounted here in south west Wisconsin
30 degree angle pointed due south
Using Enphase Micro inverters D380 's

Looking to add up to 20 more of the Canadian solar 230w panels in the future if this setup works out how I think it will.

I pay 9.8 cents per KWh and the utility dose net metering and will pay the full 9.8cents per KWh if I make more than I use.

I figured about $500 in savings per year. Is this correct??

Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: My Enphase system how many KWH will it make?

    Welcome to the forum.

    For a fairly accurate production estimation, run your specs through the PV Watts program: http://www.nrel.gov/rredc/pvwatts/

    Those Sharp panels are a tad undersized for the Enphase units, aren't they?
  • System2
    System2 Posts: 6,290 admin
    Re: My Enphase system how many KWH will it make?
    Welcome to the forum.

    For a fairly accurate production estimation, run your specs through the PV Watts program: http://www.nrel.gov/rredc/pvwatts/

    Those Sharp panels are a tad undersized for the Enphase units, aren't they?

    Yes they are undersized. But I only paid .75 per watt so. They are listed as compatible panels also.
  • System2
    System2 Posts: 6,290 admin
    Re: My Enphase system how many KWH will it make?

    What should I use for a DC to AC Derate Factor factor?
    I think enphase boasts a rating of 95%
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: My Enphase system how many KWH will it make?

    Overall, I have been using the default of 0.77 for solar panel and GT inverter derating... It may be a little bit conservative--but things age and become less efficient over time. I prefer to be conservative when doing these calculations.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • russ
    russ Solar Expert Posts: 593 ✭✭
    Re: My Enphase system how many KWH will it make?

    The 77% derate is only partially due to the inverters - the Enphase will have little affect on that number.

    Russ
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: My Enphase system how many KWH will it make?

    Russ is correct... We use a derating factor of almost 0.80 by itself to account for the difference between "marketing" power ratings and real life power ratings for panels operating in warm climates under full sun.

    Panels get hot when exposed to full sun (upwards of 35 degrees C rise--depending on ambient temperatures, wind, mounting conditions, etc.).

    When panels heat up, their Vmp drops, causing Pmp=Imp*Vmp to fall also.

    For folks that experience sub freezing winters with lots of reflective snow on the ground, they can get some pretty amazing amounts of power from their solar panels--but they also have short winter days to live with too...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Peter_V
    Peter_V Solar Expert Posts: 226 ✭✭✭
    Re: My Enphase system how many KWH will it make?
    What should I use for a DC to AC Derate Factor factor?
    I think enphase boasts a rating of 95%

    Enphase recommends an overall DC to AC derate factor of 0.819

    http://enphase.com/downloads/EnphaseAppNote_PVWatts.pdf

    Note: during the winter time the enphase will likely be limiting the output of you CS 230W panels to around 199 watts. I have CS 230 watt panels and I am still seeing them pegged at 199 Watts when daytime temps are up into the low 70s
    I don't believe the derate factor takes this into account, but I also don't think PVwatts takes the enhanced output of cold panels into account either so it might balance out.
  • System2
    System2 Posts: 6,290 admin
    Re: My Enphase system how many KWH will it make?

    All very good information! Thank you.

    Looks like I can make about 4030 KWH per year or about $400 savings per year.