On Sat, 13 Jan 2007 22:10:25 -0500, Stubby
wrote:

Jim Logajan wrote:
Orval Fairbairn wrote:
The solar cells to power it would consume a lot of its payload.

In the text "Airship Technology" Edited by Khoury and Gillett, Chapter 16,
"Solar Power" deals with design issues of solar powered airship proposals.

Using thin-film PV arrays and brushless DC motors, it states that:
"Potentially, the solar power system could weigh less than 10% of the gross
lift of the 22 tonne airship and would then be competitive in weight with
the conventional airship."

And if something other than silicon solar cells are used, the efficiency
can be much high. In 1981 I heard a talk by one John Fan who was
launching a company to make galium arsinide cells. I believe he could
get 10% conversion efficiency rather than 1 to 2% for Si .

We're up to about 18% for 3-bandgap Si, although SunPower's getting
21% with special wafers that have a long enough minority-carrier
lifetime to allow the collection grid to be placed on the backside of
the wafer. Amorphous panels produced using a web-printing process
seem to be getting around 15%, enough for one of the oil companies to
be using them to power one of their oilfields on the patch down by
Bakersfield.

Don