"Concentrated sunlight" means exactly what it sounds like- sunlight is concentrated to a greater-than-typical intensity via the use of mirrors or lenses. This is done for multiple reasons. The most important ones:
1. With proper heatsinking (cooling), a given size of solar panel may be used to capture the light from a MUCH greater area, thus reducing the resources needed, per unit area, to capture & convert the sun's energy into usable electricity. However, one must factor in the cost (financially AND environmentally- resource & pollution-wise) of the mirrors/prisms/lenses necessary for the system. Otherwise, an overall comparison to 1-sun-intensity panels becomes impossible, or at best, inaccurate and misleading.
2. Solar cells' efficiency is NOT LINEAR!!! Specifically, if you were to, say, double the intensity of sunlight incident on pretty much any type of solar panel, you will NOT get double the power output- you actually get MORE than double. This is of CRUCIAL importance in understanding why solar-concentrator PV systems are such a good idea, among the other reasons listed- in summary, they are feasibility of higher-quality panel usage and less resources necessary for, and pollution generate by, the PV-panel production process.
3. Solar cells, depending on the material(s) used for the active layer(s) as well as their quality (number & type of defects in the semicon crystal lattice), have intrinsic loss factors. By concentrating sunlight and making possible much greater effective-energy-capture-area-per-panel-area, it also becomes economically feasible to use higher-quality cells. For example, a few % efficiency increase @ 2X the panel cost for a 1-sun-intensity panel is UTTERLY impractical, whereas the same proposition for a panel onto which is concentrated HUNDREDS of suns IS practical, since the ABSOLUTE increase in power-per-unit-area for this type of system (concentrated, high-quality cells/panels) may turn out to be several times the TOTAL output of a 1-sun-intensity panel. In other words, the cost of the panel itself is much smaller in comparison to the system overall, AND any % efficiency gains are multiplied by a much greater amount per-unit-area-of-panel. Sooo, using high-quality cells becomes a lot more feasible when they are more efficiently utilized with solar concentrators.
Finally, a point of clarification: No offense Engadget, but you need to do some homework before posting about & discussing things you don't understand so well. Specifically, this part of the blurb: "In case you're unfamiliar with multi-junction cells -- no shame in that game -- they can best be described as being composed of several layers, with each slice capturing only a portion of the solar spectrum; this method of optical concentration is what has allowed cells to surpass the 12% to 18% efficiency barrier faced by most traditional modules." --The first part is spot-on; multi-junction cells DO have multiple layers, each successive layer having a lesser bandgap, meaning that it has a lower photon-threshold-energy (PV panels do not generate ANY power from photons below this level, but any energy ABOVE the threshold is wasted as heat- this is mostly why multi-junction panels are a lot more efficient than monojunction ones). So hooray for pointing that out. But the second part is EXTREMELY misleading & actually that's the reason I decided to post to this fossil in the first place. Specifically, "...this method of optical concentration is what has allowed cells to surpass the 12% to 18%..." is utterly untrue. Multi-junction panels are NOT a means of optical concentration. They are a means of more efficiently harnessing a broader band of wavelengths of incident light. Optical concentration is simply concentrating (increasing the intensity of) incident sunlight, usually by focusing paneled or parabolic mirrors onto a relatively small area of PV panel.
For disambiguation's sake, I will try to summarize these panels' differing operating principles cleary & succinctly: They are multi-junction panels which ALSO utilize solar concentration. By employing multiple junctions, efficiency is greatly increased, but so is cost. However, as stated above, properly concentrating sunlight onto a given panel will ALSO increase its efficiency- NOT JUST TOTAL POWER OUTPUT. To give you all an idea of the approximate quantitative enhancements: 1: Going from single-jcn to multi-jcn panels- typical, production, available-today-panels, at an intensity of 1 sun (normal, daylight intensity), will increase efficiency from roughly 12-16% to somewhere in the 20-35% range. 2. Going from single-jcn to multi-jcn panels- THE EXACT SAME panels as in #1, employing a heatsink & solar concentrator device such that a few hundred suns are incident on the panels (EXTREMELY high intensity), efficiency goes from approx. 15-22% for single-jcn and ~28-40% for the multi-jcn flavor. ***These values may be somewhat out-of-date or slightly inaccurate as I am going from memory, but I believe them to be "close enough" and the error, if any, being fairly small. That said, feel free to correct/enhance what I've said. In fact, I encourage you to do so!
Sorry for this post being so lengthy, but I feel there is a lot of incomplete and/or inaccurate info regarding solar panels out there. Hopefully this will clear up the picture for at least some of you. If you've read this far, thanks for bearing with me. Copyright 2008, myself. Please do NOT copy, reproduce, or distribute any part of this in any way without my explicit permission, exception being to quote/reply in this thread, as it is prohibited by law. Chances are I will say yes, but I'd very much like to know what your intended use is prior to doing so. Thanks!
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1. With proper heatsinking (cooling), a given size of solar panel may be used to capture the light from a MUCH greater area, thus reducing the resources needed, per unit area, to capture & convert the sun's energy into usable electricity. However, one must factor in the cost (financially AND environmentally- resource & pollution-wise) of the mirrors/prisms/lenses necessary for the system. Otherwise, an overall comparison to 1-sun-intensity panels becomes impossible, or at best, inaccurate and misleading.
2. Solar cells' efficiency is NOT LINEAR!!! Specifically, if you were to, say, double the intensity of sunlight incident on pretty much any type of solar panel, you will NOT get double the power output- you actually get MORE than double. This is of CRUCIAL importance in understanding why solar-concentrator PV systems are such a good idea, among the other reasons listed- in summary, they are feasibility of higher-quality panel usage and less resources necessary for, and pollution generate by, the PV-panel production process.
3. Solar cells, depending on the material(s) used for the active layer(s) as well as their quality (number & type of defects in the semicon crystal lattice), have intrinsic loss factors. By concentrating sunlight and making possible much greater effective-energy-capture-area-per-panel-area, it also becomes economically feasible to use higher-quality cells. For example, a few % efficiency increase @ 2X the panel cost for a 1-sun-intensity panel is UTTERLY impractical, whereas the same proposition for a panel onto which is concentrated HUNDREDS of suns IS practical, since the ABSOLUTE increase in power-per-unit-area for this type of system (concentrated, high-quality cells/panels) may turn out to be several times the TOTAL output of a 1-sun-intensity panel. In other words, the cost of the panel itself is much smaller in comparison to the system overall, AND any % efficiency gains are multiplied by a much greater amount per-unit-area-of-panel. Sooo, using high-quality cells becomes a lot more feasible when they are more efficiently utilized with solar concentrators.
Finally, a point of clarification: No offense Engadget, but you need to do some homework before posting about & discussing things you don't understand so well. Specifically, this part of the blurb: "In case you're unfamiliar with multi-junction cells -- no shame in that game -- they can best be described as being composed of several layers, with each slice capturing only a portion of the solar spectrum; this method of optical concentration is what has allowed cells to surpass the 12% to 18% efficiency barrier faced by most traditional modules."
--The first part is spot-on; multi-junction cells DO have multiple layers, each successive layer having a lesser bandgap, meaning that it has a lower photon-threshold-energy (PV panels do not generate ANY power from photons below this level, but any energy ABOVE the threshold is wasted as heat- this is mostly why multi-junction panels are a lot more efficient than monojunction ones). So hooray for pointing that out. But the second part is EXTREMELY misleading & actually that's the reason I decided to post to this fossil in the first place. Specifically, "...this method of optical concentration is what has allowed cells to surpass the 12% to 18%..." is utterly untrue. Multi-junction panels are NOT a means of optical concentration. They are a means of more efficiently harnessing a broader band of wavelengths of incident light. Optical concentration is simply concentrating (increasing the intensity of) incident sunlight, usually by focusing paneled or parabolic mirrors onto a relatively small area of PV panel.
For disambiguation's sake, I will try to summarize these panels' differing operating principles cleary & succinctly: They are multi-junction panels which ALSO utilize solar concentration. By employing multiple junctions, efficiency is greatly increased, but so is cost. However, as stated above, properly concentrating sunlight onto a given panel will ALSO increase its efficiency- NOT JUST TOTAL POWER OUTPUT. To give you all an idea of the approximate quantitative enhancements:
1: Going from single-jcn to multi-jcn panels- typical, production, available-today-panels, at an intensity of 1 sun (normal, daylight intensity), will increase efficiency from roughly 12-16% to somewhere in the 20-35% range.
2. Going from single-jcn to multi-jcn panels- THE EXACT SAME panels as in #1, employing a heatsink & solar concentrator device such that a few hundred suns are incident on the panels (EXTREMELY high intensity), efficiency goes from approx. 15-22% for single-jcn and ~28-40% for the multi-jcn flavor.
***These values may be somewhat out-of-date or slightly inaccurate as I am going from memory, but I believe them to be "close enough" and the error, if any, being fairly small. That said, feel free to correct/enhance what I've said. In fact, I encourage you to do so!
Sorry for this post being so lengthy, but I feel there is a lot of incomplete and/or inaccurate info regarding solar panels out there. Hopefully this will clear up the picture for at least some of you. If you've read this far, thanks for bearing with me.
Copyright 2008, myself. Please do NOT copy, reproduce, or distribute any part of this in any way without my explicit permission, exception being to quote/reply in this thread, as it is prohibited by law. Chances are I will say yes, but I'd very much like to know what your intended use is prior to doing so. Thanks!