Jones Beene
Wed, 09 Jul 2008 09:43:11 -0700
This company: http://www.g24i.com/ Has a thin film solar film panel that is flexible, and is claimed to be cheaper than the similar offerings of competitors due to lower requirement for rare elements like indium. It and others use a printed ink or dye, instead of silicon in the active layers. Because of low conversion efficiency - less than 10% of received irradiation and often a 12-hour average below 5% - and the high installation costs for small users (which is always underestimated) and the maintenance and bad-weathering issues (glossed over by the manufacturers) - these printed panels will likely NEVER make good economic sense for most US home-owners - EVEN if the panel are given away (via tax benefits for instance) and are totally free. However, and surprisingly, there is a way that they (the flexible printed panels) can make a large - and possibly surprisingly large - contribution to daytime grid power and at competitive costs for large installations. Hybridization. But that exact technique is hardly ever mentioned! Possibly because it is a combination strategy, and no one company stands to benefit from it yet. To back-track a bit: The lowest cost method for solar conversion now, according to the economic studies which I have seen, begins with a single axis parabolic trough. Yes, the new two-axis sun-tracking Stirling array - the Sandia design which is going into large-scale use is close in cost to the trough - with the advantage of being far simpler, since no steam plant is required. Here is a company claiming great things for solar Stirling: http://www.infiniacorp.com/main.php But the cost and performance edge still clearly goes to the parabolic trough collectors, which have evolved in Europe, Asia and Israel into significantly lower cost options; more so than in the USA. This is due partly to standardization and mass production - but mostly due to *political willpower* at the highest levels (which translates into lack of an oil lobby, or worse - no active Petromafia, flush with ill-gotten wealth, to deal with). Anyway the point of this post is the explication of a possible hybrid - of the solar-trough with the printed-roll collector. That hybrid as I conceive it, would begin with a cheap extruded but NON-mirrored parabolic trough, and over that base would apply a version of the flexible thin film panel, which can follow the curvature of the parabola. The "ink" used, and the protective top coating, however, would be modified so that most of the solar irradiation, the spectra which cannot be collected by the inks used in the active panel is reflected back up to the trough to be used as heat to raise steam. This would require a slightly longer trough, since a portion of energy is not being reflected - but the contribution of the direct conversion should make the hybrid more cost effective than before. Jones