On 4/18/2014 12:05 AM, yann jautard wrote: > > Le 17/04/2014 09:08, Steve Blackmore a écrit : >> >> Modern panels are designed to work in daylight and don't need full >> Sunlight. >> > Well not really. There two main technologies, cristalline and amorphous. > > Cristalline cells needs full sunlight to deliver some usable power. > Their efficiency is better. > > Amorphous cells can use indirect light like you have on cloudy day. But > their efficiency is a little bit lower, wich is not a problem because > they are cheaper, so for the same peak power you will pay the same. but > you need more surface to install them.
All silicon PV panels lose some efficiency over time. The drop is fairly steep initially then tapers off to a very slow decline. Crystal panels take a hit of 3% to 5% their first year then about 1% per year for several more years. Dunno if that's 1% of original capacity or 1% of the reduced capacity each year. Amorphous panels will drop up to 10% of their initial efficiency in a few years, so an installation using them should be oversized by at least 10% above the amount of power required. Each manufacturer has different claims and guarantees about the efficiency loss over time, but it's always a safe bet to oversize the capacity by plenty then never expand the draw to use the "extra". This efficiency loss is a good thing for building systems with used panels. Get "well seasoned" panels that have bottomed out on their initial rapid decline and you won't have to oversize the capacity - but get them tested for output in full sun. One extra-ordinary 30 year old panel still delivered 97% of its initial capacity (in 2010) and more amps than the spec sheet. (Had to dig this out of the archive as the current site has it paywalled.) https://web.archive.org/web/20100524144011/http://www.greenbuildingadvisor.com/blogs/dept/musings/testing-thirty-year-old-photovoltaic-module Temperature also has an effect on output, efficiency loss and the overall longevity of the panel. Keeping them cool (which is a bit difficult for a dark object placed into direct sunlight) reduces efficiency loss and increases output. And then there's this. https://en.wikipedia.org/wiki/Concentrated_photovoltaics ------------------------------------------------------------------------------ Learn Graph Databases - Download FREE O'Reilly Book "Graph Databases" is the definitive new guide to graph databases and their applications. Written by three acclaimed leaders in the field, this first edition is now available. Download your free book today! http://p.sf.net/sfu/NeoTech _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
