PV cells and arcing Forum: SSI-List
Thread: PV cells and arcing
# 22300 byhkhenson on March 8, 2009, 4:43 p.m.
Member since 2022-08-22
> Last I heard, PVs generate potential differences in the 5 Volt range.
>How do you get plasma arching at that low a voltage?
You don't. But you have to stack them in series to get the voltage
you need to run the transmitter.
Consider a 5 km x 5 km PV power sat wing.
From the end it might look like this \_/\_/\_/\_/\_/ where the
slanted section are coated with aluminized Mylar to give a mild 3x
solar concentration. You almost get the concentration for free since
the structure has to have some thickness to resist bending. Five
km/3 is about 1600 meters. Each of the 5 flat sections would be
about 330 meters wide.
To keep down conductor mass and reduce I^2R loses, the voltage across
the whole array of cells could be up in the 100,000 volt range. (If
so, the current from a wing would be 50,000 amps or ten amps per
meter.) Each of the 5 sections of cells would need to generate
20,000 volts or 60 volts per meter. That would take about 123 cells
per meter in series--which is not far from current
practice. http://www.amsolar.com/am100.html
Before getting into the complex problems of insulating the PV strings
from the power sat frame, and conducting the power to the transmitter
to and through slip rings, you need to think about a production
target of PV cells of around a GW/day--though it probably would start
smaller, maybe 1/4 to 1/2 GW/day and is further reduced by the
concentration factor.
Between jet engines and steam turbines the world is not that far from
a GW/day production of rotating machines.
Keith