How power produced by a solar cell is affected by its distance from a light source.

Theory

I expect that as the solar cells are moved closer the light source the higher the power they will produce.

As light moves away from the source it spreads out at all angles the further you are from the source the less intense the light will be.

P = I V

Power = current x volts

P = FA

Power = flux x area

Flux = P/A     Area of 4 solar cells that I will use is  0.0077m2

This means that the higher the flux the higher the power as we are not changing the area of the solar cells as this remains is constant. So as flux increases so will the power and this will happen as the cells are moved closer to the light.

Diagram

Using what I know about space and the way light intensity changes the relation I expect is.             Power = 1/distance2

Plan

To measure power by a solar cell and distance light source is away form it, then to plot the distance against power to get a strong inverse relationship.

Then to plot a

The circuit I used for measuring the power was set out like this. The voltmeter in parallel measuring the potential difference across the cells and the a ammeter in series measuring the current flowing through the circuit.  

As you can see I have used a resistor in the circuit this is to minimise wasted energy lost by the power supply or solar cell. If the circuit did not have a resistor in the current would flow round very fast, having a large current creates more heat as speed is greater and creates large amounts of wasted heat energy, giving miss-leading results. However this was probably this would not as the current is dependant on the intensity of the light nevertheless if there was no external resistance in the voltage would read zero, as there is no potential difference across the solar cell, so calculating the power would be inaccurate.

Method

I measured the voltage produced and the current drawn by the resistor, this then gives me the power produced by the solar cells. I measured these at incremental distances from the light. For the light I used a standard desk task light that uses 60watts. I measured at 10cm increment distances from 50cm.

If I were to carry this investigation out again I would ensure that the light condition were kept at a constant level, this could be done by carrying out the experiment in a blacked out room. From my graphs I have proven my prediction of power being proportional to 1/distance2. From my graph that plots this there is a clear strong correlation between the two sets of data.

If I was to carry out this experiment again I would make sure the lamp cover dint create a shadow on the solar cell while up close by removing it leaving a bear light. I would also use a better quality solar cell as the one I used was in efficient and was inconstant in power output as temperature changed. I would also conduct the experiment in a room with  a constant temperature so the experiment is more accurate. I would also use a room with only one light source and with no background light. Also I would stay in one place throughout through the experiment so my body doesn’t reflect the light differently as the experiment is carried out as it will alter the intensity of the light hitting the solar cells at different times.