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# How many watt’s/sec does a 3″X6″ solar cell collect if it says “3 watts solar cell”?

How many watt’s/sec does a 3″X6″ solar cell collect if it says “3 watts solar cell”
Is this 3 watts per second, minute, hour.
Lets also say it is averaged throughout a 10 hour day of sunlight

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JoelKatz January 2, 2012 at 11:52 am

It’s 3 watts. Power (the rate at which energy is collected or expended) is measured in watts. If you average it through a 10 hour day of sunlight, it should average a bit less than 3 watts. A 3 watt solar cell collects, under perfect conditions, 3 joules of energy every second.

In a full 10 hour day of sunlight, the cell would likely collect somewhere around 70,000 joules of energy.

Breath on the Wind January 2, 2012 at 12:18 pm

Your confusion is between ratings of power and ratings of energy. Look on the draw side as you can find a label on almost any electrical device that plugs in. A heater for example might be a 1500 watt heater. That is how much power it draws at its full setting.

But electrical energy values also need a component of time. Your household bill is rated in KW-hrs(1000 watt-hours.) In the US the average KW-hr costs about 11 cents. If you left that 1500 W heater on for an hour it would consume (1500 watts x 1 hour) 1.5 KW-hr of electrical energy.

OK, back to your issue. Your solar panel has a power rating of 3 watts it can produce. There are several ratings for PV cells but this is probably in full noon day sun, no clouds in Arizona pointed directly at the sun. You are unlikely to achieve this rating. If you did remember that it is likely DC power and different from your household AC power.

But lets assume you could coax the unit to perform under perfect conditions endlessly. Then in one hour it would produce 3 watt-hour of power (DC: a little more than the energy in one AA battery) In 10 hours it would produce 30 watt-hours of power and it would take (1000/3 =) 333.3 hours to produce 1 KW-hr DC (under perfect conditions.) What is likely is 50 to 75% of the rated output (or less) depending upon conditions.

J. January 2, 2012 at 12:26 pm

It is just power over time, since your power is nearly constant, take any time increment you want.

3 watt seconds, 3 watt hours, etc.