# How to obtain the I-V characterisation curve of a-Si solar cell?

1. Aug 26, 2009

### feel luck

How to obtain the I-V characterisation curve of a-Si solar cell??

Hi guys,

I am currently doing a university project on the reliability studies of a a-Si thin-film solar cell with specs of 3V@25mA. However, I am stuck at the first step, which requires me to obtain the I-V characterisation curve to derive the parameters of Isc,Voc and Pmax. My lab has a Keithley's 2636A Sourcemeter, which I am having trouble to operate. I am using a Philips PL E-C 11W bulb to illuminate my solar cells as the previous Philips 100W tungsten bulb was melting the encapsulation of the solar cell. Both bulbs also did not manage to produce the standard I-V curve of a solar cell.

Is there anyone who is using the Keithley's 2636A sourcemeter and knows how to obtain the I-V characterisation curve of a solar cell with the TSP-link software?

If not, are there any other simpler ways to obtain the I-V curve of the 3V@25mA solar cell?

feel luck

2. Aug 26, 2009

### Topher925

Re: How to obtain the I-V characterisation curve of a-Si solar cell??

A regular tungsten bulb is a terrible light source for PV testing since they are designed to operate with sunlight. Sunlight and your bulb have two very different emission spectrums so your current set up will not yield the actual performance of the PV cell.

In order to develop your V-i curve you need a variable load. Something that will go from open circuit to a complete short of the cell and everything in between. You step your load in fixed increments and record your voltage and current over time. You then average that data at each step and plot it to get your V-i curve.

To determine your MPP (maximum power point) you plot "voltage x current" and apply a curve fit to that curve. Then differentiate that curve and set it equal to zero, then solve for current density. That current density is the point with greatest power. Plug that value back into your equation for your power curve fit and you will then have your maximum power.