In reply to Jouni Valkonen's message of Wed, 3 Oct 2012 10:00:18 +0300: Hi, [snip] > >On Oct 3, 2012, at 6:22 AM, mix...@bigpond.com wrote: >> I can't guess what effect the lenses would have, but I'm guessing it would be >> minimal, since they only appear to cover a fraction of the total area. > >Focusing the light with lenses will increase the efficiency of the PV-cell by >20 to 75 folds. So 75 fold increase in efficiency of PV-cell is by no means >minimal improvement.
That is true for the area of solar cell which is directly at the focal point of the lenses, which is a very small fraction of the total at any one instant. You can get a better feel for the effectiveness of the lenses by taking note of the fact that they can only concentrate light that is falling on them, and since the total lens area is only a fraction of the total surface area, their net effect will be minimal. Note that true gain from lenses comes only when you put solar cells at the focal point of the lens, so that the lens area is much greater than the solar cell area, resulting in more light falling on the cells than would be the case without the lenses. This reduces the investment cost of the cells, because you use far fewer of them. > >The problem with PV-cells is that without effective cooling they will overheat >in southern latitudes if they are facing midday sun directly for prolonged >time ?\ even without lensing. And when PV-cells are overheating, it will >reduce not only the efficiency, but also the lifetime of PV-cell is >compromised. This may be a good reason for rotating the setup, i.e. giving the cells a chance to cool. > So lensing with conventional flat panels is pretty much out of the question, > because effective cooling is too expensive to organise. Perhaps not. If you back your panels with cooling tubes, then the heat can be used for solar hot water, just as is currently done without the solar cells. You would end up with a combined unit that produced both electric power and hot water. >However this cone architecture of solar cell does solve the cooling problem >quite creative way, without increasing too much the total cost. That I agree with. > >Therefore, don't you ever use the common sense, because it is always >misleading you! It is better to use scientific sense. ;-) That is my "common sense". ;) > >It is interesting that the total cost of the electricity with this technology >could be as low as $90 per MWh. This means that it is almost cheaper than >conventional coal power. ...according to their projections, or according to measurements I wonder? Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/project.html
