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# Solar Panel: How Can I Calculate The Power Output Of A Solar Cell? (3/26/2012)

what are all the things i need to know to calculate power output (in KWh) for different solar cells with different efficiencies,

i know i need to know the number of hours of sunlight, watts produced, amp hours, efficiency of the cell
how do i put it into the form of an equation

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Tecchas March 26, 2012 at 3:59 pm

These links will hopefully help you determine the factors you’ll need to calculate the power output of a solar cell: http://www.ehow.com/how_7827904_calculate-solar-cell-output.html , http://www.pvsolarchina.com/how-to-calculate-the-maximum-power-of-solar-cells.html , or http://www.wind-sun.com/ForumVB/showthread.php?t=5228 .

Best of wishes.

Stephen M March 26, 2012 at 4:14 pm

Power (watts) is simply current (amps) x voltage (volts).

Power used has to take into account time so that is where something like KW hr comes into play. It is simply watts x 1000 x time (hrs). So if something uses (or produces) 1000 watts of electricity for 1 hours, this equals 1 KW hr.

Efficiency is another thing altogether. Hopefully you would have some literature telling you the cell efficiency otherwise you will have all sorts of issues trying to calculate it with accuracy as the size of the cell comes into play, as does the sun angle and your latitude, cloud cover or even just smog in the air, etc.

If all you really want to do is calculate the power output of a solar cell, then most of the things you mention in your question are not necessary and you just need the current and voltage for a particular load.

123456 March 26, 2012 at 4:43 pm

J. March 26, 2012 at 5:22 pm

The efficiency of the cell or panel is independent of it’s output. It is only a factor when you are trying to maximize the power production from a given area. A panel of a power rating of 100 Watts with a 12 volt rating produces 8.33 Amps continuous while exposed to the sun at reasonably optimal exposure.

Most cells are nominally rated so the datasheets you would get with the cells or panels will give you those numbers as 12, 24, 30, 36 volts, etc. Current will be listed as a nominal value as well. This is not the peak output, as that can and often will be higher.

Now, if you calculate what the average day length of your lattitude is, you can reasoanbly calculate what optimum maximum output would be by determining the Kilowatt hour production of the panel times over the course of 1 year/365 days. So once you know an average daily production value, you multiply by the time period in question, be it 1 week, 30 days, 1 year, 2 years, etc.

So a 100 watt panel produces 1 Kilowatt hour in 10 hours. The power is a function of volts multiplied by amps. 2 panels of the same wattage can produce the same power over time even if one was a 12 volt nominal panel and one were a 24 volt nominal panel because of proportionality of the equations with those values.