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From: roger034@gold.tc.umn.edu (Brynn Rogers)
Subject: Re: Solar Insolation Levels
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Date: Mon, 1 Aug 1994 18:25:59 GMT
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In article <ykgcqc4w165w@sfrsa.com>, Ed Severinghaus <eds@sfrsa.com> wrote:
> 
>Can't find my reference for how many watts per square meter of 
>convertible energy there is in sunlight at the earth's surface <I can 
>figure out the effects of lattitude!>.  Anyone know this? 

  According to my source Brian Lawrence, who was a member of Mankato State's
Sun Rayce '93 Solar car team,  The insolation varies as a function of time of 
day, time of year, lattitude, and altitude.  Probably it is just the angle of 
the suns rays hitting the atmosphere, and how much atmosphere they have to 
penetrate that counts.  He could not remember any of these numbers off the
top of his head, they had a book that was an inch thick full of tables
of this.

> Also, last 
>time I asked, it was said that the cheap solar cells were in the range of 
>up to 6% efficient.  Anybody know what progress has been made in the last 
>few years or so?

Amorphous cells are 5% to 6% efficient, with new technology ones up to 8%.

>And how about the more expensive yet commercially available types?

15% to 16% cells cost $7 each for a 4x4 inch square cell. (In quantity)
One of these cells puts out 1.5Watts,  .5 volts and 3 Amps.  These are the
cells that Mankato State used on their car.

Space Grade cells are 18% efficient, and run $13 for a 4x4 inch cell
in quantity.

Quantity they are talking about is 1000 piece.
These cells need a bunch of work yet to be mounted, they come bare.  
Leads must be soldered to both the back and front sides and the cells
must be protected from the environment (mosture is bad).

All these numbers are from our Solar expert, not me.

--
Brynn Rogers     roger034@gold.tc.umn.edu

