Thursday, 9 June 2011

Solar Panels

Wow, it's been 5 months since I posted last. I really got to get back on the blogging thing again.

Quick update, I've finished the first year of my Master's. I'm not doing particularly well or even as well as I'd hoped. I just finished a module in RF design and Digital Systems Design 2. I had 6 assignments for RF and 2 large assignments and a IEEE paper to write for Digital Systems Design 2. I may upload some of these at a later date, once I clean them up, improve on them and then I can use them as part of my very own portfolio.

Last year I bought a number of broken photovoltaic cells for about $20 on ebay and I never got around to using them, due to lack of time and space to do so. So on last Tuesday night, I finally got around to starting it all. In the picture at the top of this post, you can see my test setup. I built the wood panel from 1 90cm x 60cm hard back board, 2 x 90cm rails and 2 x 45 cm rails. I've left gaps on either side for wires to come out, in case I want to place plexiglass on top to use outside.

Now as you can see in the picture on the left here, I've made quite a stupid mistake here. I've wired the solar cells in parallel, instead of in series. This means that the voltage will only be a fraction of the total possible voltage and this fraction decreases with every cell I attach. For two cells, 1/V(total) = 1/V1 + 1/V2, which is halved for two cells, a third for three and so on. Currently the measured voltage indoors under a fluorescent light is about 150mV and 20mA, which is nowhere near the results I need. I went out this morning to see what my new 3 cell panel would work and I got a reading of 565mV with 150mA. Much better, but still way below what I was expecting. By placing the cells in series, The voltage will be additive and the more cells I add, the greater the voltage will be.

Tonight, I think I'm going to keep my parallel 3-cell and I'll build a 3-cell series as well so that I can compare the results and show the difference between the two.

I'll have more on this over the next few days, watch this space.