(George) wrote in message . com...
(Alex Terrell) wrote in message . com...
Any one know ....

How many W/m2 can solar panels produce, assuming concentrated or laser
light?

The application I was thinking of was for a Solar Power station at
Earth - Moon L1, beaming laser power to vehicles on the moon's
surface.

I think a mechanical digger or large dump truck might need about 100
KW. Alternatively, could the laser be converted directly into heat to
drive a closed cycle engine?

For these slow moving vehicles, tracking should not be a problem.

The other application is reducing solar cell area by preconcentrating
light on it, since mirrors are lighter and cheaper than solar cells.

Alex

A solar panel converts roughly 7-17% of the light it recieves into
electricity. This depends on heat and the cells themselves. For
example a silicon PV cell loses half its efficiency between 0 C and
room temp. Basically, of the light hitting the solar panel, about
50-60% gets absorbed with about 5-15% getting converted to electricity
and 40-50% getting converted to heat, so concentrating the light means
more wattage hits the panel so more electricity gets generated, but it
also heats up the panel lowering efficiency. I don't know the wattage
of concentrated light, but for a laser, assuming you can put big
enough panels to collect 90% of the light from it, a 100 KW laser
(should be available soon using diode pumped lasers, so no fuel) you
would get 90 KW hitting the panels, so you would generate 6-15 KW of
electric power but about 38.7 KW of heat. That is a lot of heat you
have to disapate. You also need to store some of that electric power
as most 100 KW lasers are pulsed (I don't really know of one that
isn't), so your actual throughput is less. I don't know much about
solar thermal solutions but that may be better (using the laser to
heat a convective fluid to run a turbogenerator).


You guys can more efficiently transmit energy using microwave
antennas. You can get 60% efficiency by radiating microwaves onto an
antenna that is equipped with microwave diodes. This would be the
preferred method of transmitting power.

Zoltan