About solar cells

Some links

• https://en.wikipedia.org/wiki/Theory_of_solar_cells

  • interesting due to model section

• https://en.wikipedia.org/wiki/Maximum_power_point_tracking about optimizing energy output from solar cells

• https://en.wikipedia.org/wiki/Multi-junction_solar_cell just for reference

Model of a solar cell (from https://en.wikipedia.org/wiki/Theory_of_solar_cells) We are using tripple junction so the diode voltage is up to 2.xx Volt

So using solarcells is to get as much energy out as possible.

As seen on the very primitive experiment below you must be below a certain voltage, otherwise the diode will start opening for cureent so you loose just energy.

So as high as possible voltage on the cell - just below where the diode opens. Its called maxium power point tracking(MPPT).

In the experiment a variable resistor is used. And Ohms law gives a voltage (U=RI). So As you can see on the curve too high and too low resistans is not optimal :-)

Datasheet

• Azur cell tripple junction

  • (tripple junction means there is three diodes in series in the cell)

  • each diode has its own light frequency area so in total they absorb as much as possible

Experiment

A simple experiment was carried out to see if it was possible to reproduce the well known I V curves.

Setup schematic. Vary resistor and measure current and voltage The resistor range is from 0.1 ohm to 1000 ohm in 0.1 ohm step

Simple measuring setup at my office. The overheadprojector is a … Medium 2036 28 cm * 28 cm glas plate bulb: philips focusline projection lamp 7787XHP 36V / 400W

First solarcell was exposed to two office lamps. Low energy - so no energy in the solarcells.

Next an overheadprojector (400W) was used which gave up to 0.5 W from one cell - experiment approved.

Results

• spreadsheet

• spreadsheet as pdf

• CSV file

Data and PV and IV plot for overheadprojector experiment

Data and PV and IV plot for table light and overheadprojector experiment You can see there is not much energy in a low energy lamp…

Jens