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Solar Electric Cells

Charlotte Said:

Why isn't there an electric car available with solar cells on the roof/trunk?

We Answered:

Becuase it would end the oil business

Maxine Said:

Why can't we embed Solar Cells on cars and use them to help recharge Batteries on electric cars?

We Answered:

You can. Solar powered trickle chargers for a lead acid battery can be found at any spare parts dealer. A lot of 4x4 drivers use them to keep batteries charged while parked up and to be able to use car fridges without having to run their motor to keep up charge.All so there is a race ? across Australia Nth to Sth for solar powered cars.The only hold up to electric cars is the people that build them. (See "Who killed the electric car")

June Said:

Why isn't every rooftop in California, a solar-electric cell?

We Answered:

This may come. The issue at this point is that solar panel are still fairly expensive.

Kathy Said:

How do I test the power, electric current, and efficiancy of solar cells?

We Answered:

The power and current should be fairly easy, if you know what the rated voltage of the solar cell is.

You can put the solar cell in bright light and connect a variable resistor. Starting with the resistor set at its highest resistance, slowly adjust it while monitoring the voltage across it with your voltmeter. When you see the voltage reading drop to below the rated voltage of the solar cell, you have reached its maximum current output for that rating. Back off the variable resistor until the voltage is back within its rating. If you can now calculate the current at that point by first measuring the resistance of the variable resistor as it is now set. You can calculate the current using ohms law

Current = Voltage / Resistance So a reasonable current rating woul be = the cells voltage rating divided by the resistors value just before you observed a drop in ouput voltage.

The efficiency will be a little harder, because you need a way of measuring the amount of light that is hitting the cell to calculate the energy input.

If you can determine the watts of power hitting the cell, you could then easily compare to the watts of power provided at the output in the form of electrical current.

In any case, to calculate the electrical power output of the cell, we would go back to the original setup. You can calculate the power in your original test by multiplying the voltage reading by the calculated current.

So if you measure 10 Volts across a 100 ohm resistor you would calculate the current like this:
Current=Volts/Resistance Current = 10 Volts/100ohms
so the current would be .1 amps or 100 milli amps.

The power would be :
watts=Volts X amps or power = 10 Volts X .1 Amps = 1 Watt

Ok, now if you can get you hands on a light intensity meter that measures light output in lux, you can now do a comparison.

First of all, basically take that meter and measure the light intensity at the same location and under the same lighting conditions as you are testing the photocell.

One approach to control that might be to do all of this testing, including the previous in cardboard box that the inside has been painted with flat black paint. Inside of that box install a 60 watt light bulb as your light source. This will give you a relatively consistant and repeatable set of test conditions.

Ok, so taking the light measurement gives you lux, which is light intensity over a specific area. 1 lux = .001496 Watts/sq. meter.

To do a comaparison, you need to measure the size of your solar cell and calculate is area in meters. A sq. meter is 100cm by 100cm in size, for a total of 10,000 sq cm.

So if your solar cell is 10cm by 10 cm in size, it has an area of 100cm. This is 1/100th of a sq. meter. The light energy hitting it is 1/100th of that which would be hitting a full meter, so you divide the lux constant by 100.

So if 1 lux = .001496 Watts/sq., then 1 lux = .00001496 watts per 100 sq cm.

Take your light measurement, multiply by the lux factor based on your solar cell area, and you now have the watts of energy being seen by that solar cell.

To calulate the efficiency, you divide the watts of electrical power that you originally calculated by the calculated watts of light power and multiply that by 100. The number you get will be the solar cells efficiency in percentage of power out to power in.

Well, it all sounds complicated, and it is. But definately doable.

Sorry it got to be such a rambled on explanation, but thats it!

Good luck!

Ramon Said:

What kind of metalloids are used to make solar electric cells?

We Answered:

Silicon, their atoms knock off the electrons and they form a circuit to convert the heat and light energy into electricity.
There are also dark solar cells made out of glass with black wires, which use the energy to directly heat water.

Remember revising this today, so it should be something along the lines of that! Hope this helps.

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