Trying to figure out seasonal range for solar energy hitting my PV array
My question is basically this: is there a reliable way to calculate the seasonal difference in maximum available solar energy for a particular latitude?
This past November I fired up my new array of twenty-eight LG 365-watt PV panels, for a total designed output of 10.2kW (https://www.lg.com/us/business/solar-panel/all-products/lg-LG365Q1C-A5 ). So the system has been running for over 3 months now, and on the sunniest days, production always tops out at around 7,880 watts. I’m at about 41-degrees latitude, and the system is mounted on a roof that faces SSW and is at an angle of about 40 degrees. I know that in winter the low angle of the sun should lead to more attenuation of solar energy, but I figured that I would at least see a little fluctuation in maximum output from month to month as solar angle changes; but on every single sunny day, the system has produced the same maximum output.
I realize that the output rating is based on ideal testing conditions (in a lab, I assume), and if you go by the Nominal Operating Cell Temperature rating, the rated output more closely represents what I’m seeing. I know that I can just wait until later this year to get the real answer to this question, but can I estimate if and how much more energy the system will produce in summer? Should it ever produce more than the max 7.9kW that I’m seeing? Or will it likely produce more daily power solely on the fact that there are more hours of sunlight in a day?
the main reason I’m asking, other than that I’m impatient and don’t want to wait for actual data, is that I was surprised how difficult it was to find detailed information about calculating seasonal production differences, even from the companies that produce and install photovoltaic equipment.
Thanks in advance for any light you can shed on the subject! 😉
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