Australia's Science Forum

Hi all

Just to see what happened I set up a small (1.5V) solar panel and voltmeter (set on 2V dc)to see what happened. It was positioned near a window, on a day when it was totally blue sky, the voltage on the meter was about .75V and then today when its overcast it was about 1.3V(the panel was in the same position)
What I was wondering is why is this so?

Different time of the day ( UV) ?, different position /angle,? wires loose/better connected this time? Grubby fingermarks, gremlins and hobnobs? Meter tempramental? Did you have it behind glass last time?!!

Same time of the day, Same Postion behind glass, Didn't change anything to do with the wires, no new fingermarks on window.

Don't solar panels lose their effiency when unused for a time? If that's the case and they were subjected to light again, the longer in use the more efficiently they work. Saw it somewhere but can't remember exactly but it was to do with the silicon content of the panels.

Hi All,

Just a bit of a hint. We know UV cannot penetrate through glass!! A perfect example is having to make sure that I use Quartz sample cells when I fire UV radiation into specific samples when doing UV analysis of drug samples back at Uni..

Keep that in mind when doing experimental work with these cells.....

Cheers,

Robb.....

Hi

You can get some very strange results with small cheap solar panels. One single panel is actually made up of a number of smaller silicon arrays, which in turn are all connected up in parallel to give you the required amperage at a certain voltage. What can happen is that the solder joints on cheap units are imperfect giving you different voltages and current readings. This is a classic situation with cheap solar lights and why they no longer work, as the voltage is not high enought to charge the battery. Now combine this with varying solar radiation conditions ........... and OH bugger what's going on

Kim

Solar cells have "wired" connections inside. It maybe that some of these are a bit loose. Perhaps you may have squeezed the connections. So don't worry too much about your result.
Some of the commercial solar cells that have 20 year warranty "drop" cells. It just means a bit of voltage loss but they still function just fine.