how much a/c will system produce

SystemSystem Posts: 2,511 admin
Thank you in advance everyone. What is the formula to calculate your anual a/c production from a grid tied solar system. I have a 5600w d/c system with a 15% loss due to orientation and wire loss. Located on LI NY which should be 4.5 sun hrs per day. I have most of the info but i just cant seem to get the total production....Any help?


  • TnAndyTnAndy Solar Expert Posts: 249 ✭✭✭✭✭
    Re: how much a/c will system produce

    I was told here in TN with 5.5hrs/day we would get about 1000kwhrs/ per 1000 watts of panel on a fixed array oriented correctly. I have single axis tracking arrays, and am getting what looks like will be about 25% more than that figure. ( we are 7 months into the first year of production ).
  • BB.BB. Super Moderators, Administrators Posts: 30,520 admin
    Re: how much a/c will system produce

    There is a pretty simple web program to use called PV Watts.

    Just pick the city nearest yours with similar weather patterns (watch coastal vs inland cities--for example) and fill in the blanks. Use the defaults for Grid Tied power (0.77 derating factor, down to 0.52 for off-grid AC power using flooded cell batteries) and away you go.

    For example, use NY City 5.6 kWatts of solar panels, and assume you are pointing due east (90 degrees) with a 45 degree slope roof:
    Solar Radiation (kWh/m2/day)
    AC Energy (kWh)
    Energy Value ($ at 14.5 ¢/kWh)
    1      1.78          225        32.62   
    2      2.65          316        45.82   
    3      3.28          425        61.62   
    4      4.31          533        77.28   
    5      4.78          595        86.28   
    6      5.28          618        89.61   
    7      5.16          613        88.89   
    8      4.82          581        84.25   
    9      3.76          440        63.80   
    10     2.86          352        51.04   
    11     1.72          199        28.86   
    12     1.49          176        25.52
    Year   3.50 HrSun   5073kWhr  $735.59[/FONT]
    The above program accounts for actual average sunlight over ~20 years. Does not account for very hot (or cold weather) or if you have shading at certain times of the day.

    There is also a companion site that has PDF files of the data--You can look at those and get an idea of how variable the sun is for your area (they plot the ~20 year data month by month so you can see--for example if you have marine layer--how much variability over the years you have for your region).

    Does this help?

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