How to estimate Solar energy on certain direction pointed surface?

If I mount a flat surface which points to certain constant direction. At certain place of the world. I now need to estimate the maximum amount of Solar radiation energy which this surface can get during certain time.
Is there a PC program or an algorithm that can make this estimate for me?

2 thoughts on “How to estimate Solar energy on certain direction pointed surface?”

  1. N - Lothringer Bur

    What you want is called a "solar declination" calculation.

    Yes there are some softwares or at least calculation patters for that, Google "solar declination"

  2. That’s the National Renewable Energy Labs site, and will give you insolation (amount of sun) for your area. If you have an ideal location and roof, you would choose, Average, Annual, Flat plate tilted south at latitude. Then a map will come up. This map takes into account weather conditions, too, because it is derived from actual measured data. Thus, a dry, cloudless location such as Phoenix shows more sun than a place with more clouds like Honolulu.

    Let’s say the map says you get 5 hours equivalent sun per day. The word "equivalent" is important, because it factors in that morning and evening sun are weaker than noonday. The number you get means the equivalent of direct, noonday sun for 5 hours, even though it may be 12 hours from sunrise to sunset. And it’s an annual average, so you will get more in the summer, less in the winter. Ok, so you take that figure, say 5 hours, and multiply it my the size of your array in watts, and multiply it by 365, the number of days in a year.


    5 hours/day X 3 kW array X 365 days/year = 5475 kWh/year.

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