Right, telescope uses clear glass in a lens to magnify and transmit light. Ones with mirrors do indeed reflect light to concentrate it in a smaller area.
Solar cell’s function is to absorb light and convert to energy, not reflect or transmit through itself. If you think about it, if a solar cell reflected light, it would not function.
So, still does not make sense from a physics standpoint.
Greg
Remember Solyndra,that company that went bankrupt?
https://en.wikipedia.org/wiki/Solyndra
“The panels were made of racks of cylindrical tubes (also called tubular solar panels), as opposed to traditional flat panels. Solyndra designers thought the cylindrical solar panels absorbed energy from any direction (direct, indirect, and reflected light)”
Maybe they thought that, but did not?
-Ted
Hi all:
Just a few theoretical calculations on an interesting subject.
At the Earth’s surface, on a clear day, incident solar energy intensity is about 1kW per square meter. This is the intensity on a plane perpendicular to the solar rays. This intensity is more or less constant along the year, irrespective of solar inclination, if we assume that atmospheric transmissivity is constant.
A small G gauge locomotive (LGB Porter), pulling a small 6 axles train (three four wheeld cars), can operate at a reasonable pace under 12V, drawing 0,5 Amps, that is, 6W.
The effective energy produced by a solar panel, assuming the quoted 1kW per sq. m is:
E = 1000 × Areap × sin α × Efficiency x Meteo
where E is the energy output of the panel (W), Areap is the area of the panel (sqm), α the incidence angle of the sun rays on the panel, Efficiency the global efficiency of the panel and Meteo the transmissivity of the atmosphere compared with a clear day.
The required area of the panel can be obtained by:
Areap = E / (1000 × sin α × Efficiency x Meteo)
If we admit a small LGB Porter needing 6W, a clear summer day near midday with α = 45° and Meteo = 80%, and a global panel efficiency of 15%, we will have, for flat and horizontal panels installed on the top of the trailing cars:
Areap = 6 / (1000 × 0.70 × 0.15 x 0.80*) =* 0,07 sqm = 110 square inches
Limiting the maximum width of the panels to 5’’, we will need a total length of panels of 22”, that is, about 7’’ by panel assuming three trailing cars, which is just about doable (even if not very elegant) if the line does not have too many shaded spots.
José Morais
Manager of the Lapa Furada RR
Yep, interesting your calculation matches my estimate of 3 cars, but I raised it to 5 to be practical.
Greg
When I installed the solar panel on the flat car I needed to get the most bang for my buck. Since the panel is twice the width (6") of the flat car, the only logical thing to do is glue the panel to a 3" PVC pipe that I cut in half and anchor that to the trailing car. Size and shape worked perfectly! Then I housed two 14.4V 2700mah Nimh battery-packs underneath, a MC1A smart charger at one end and a DC converter at the other. At full sun the panel would charge one battery around 250 - 300 milliamps per hour. You can increase the current draw by increasing the size of the panel or the number of cars is parellel, but that will never make it around some of our layouts. I did investigate a flat tracking panel while the loco was in motion, but it would not turn as quickly as I would like to run my train. It would always be behind the curve, so to speak.
My hat off to anyone who has a better idea, but since I’m in the battery business…this was a very cool idea sitting on the table at several of our trade shows.
solyndra cylindrical panels (clear reasons why they failed…)
