Measurement of insolation

[Tkian]

hi,

I have seen from a response indicting that by using a single solar cell, mounted it in the same orientation as the collector and measure its short circuit current, it is possible to have accurate measure of the insolation.
I would be glad if anyone chould provide me a detail working procedure or recommand any information on this method of measuring radiation
Thanks in advance!

regards,
Tkian

 

[GregLocock]

It doesn't give a calibrated value, it merely gives you a reference to work from when measuring the power output of another solar power system. You just hook up the two wires from the cell to your multimeter, and put it on the 10 amp DC range. The short circuit characteristic of PV cells is pretty linear with respect to insolation. I suggest that you cool the cell to a standard temperature, or only expose it for short times, if the day is very sunny.

Cheers

Greg Locock

 

[Tkian]

Greg Locock,

I had used a 30mm x 30mm solar cell, hook up two wires from the cell to a 100ohm resister and parallel to a multimeter. I realised that the voltages that I got from the multimeter is pretty linear with the radiation data captured by a pryanometer. Could you advise me whether the solar cell can be considered calibrated if I could form a mathematical relationship between the votages and the radiation data. In your last response, you mentioned that I should cool the cell to a standard temperature, or only expose it for short times, if the day is very sunny. Could you tell me why is this necessary (would it be possible for the cell to be placed under the sun the whole day.)

Thanks again.

Regards,
Tkian

 

[GregLocock]

No, you HAVE to measure the short circuit current, not the current into a load. 100 ohms is a very resistive load for a single cell.

The reason that you have to worry about cell temperature is that the voltage is very temperature sensitive, and this will alter your readings.

You should be able to get graphs of these characteristics from the manufacturer, or for an equivalent product off the web, with a bit of persistence. Failing that read Dr Martin Green's book. Cheers

Greg Locock