# Aerospace At what altitude does a solar panel see a noticeable increase in wattage/cubic meter

1. Apr 26, 2012

### OtherRealm

At what altitude does a solar panel see a noticeable increase in wattage/cubic meter if it is lifted into the air? I understand the maximum is a bit over 1 kilowatt/meter2 at sea level (not actually converted to usable energy, this is much less and depends on the technology) but that this amount obviously increases as an object reaches the exosphere and beyond. Would there be a noticeable increase at say, 12km or at the top of the thermosphere?
I found one useful site: http://www.pages.drexel.edu/~brooksdr/DRB_web_page/papers/UsingTheSun/using.htm but it is talking mainly theoretical. Does anyone know of studies that have been done to look at real life w/m^2 at various levels of elevation? Thanks.

2. Apr 27, 2012

### Staff: Mentor

Re: At what altitude does a solar panel see a noticeable increase in wattage/cubic me

Welcome to the PF.

http://en.wikipedia.org/wiki/Insolation
"Direct insolation is equal to the solar constant minus the atmospheric losses due to absorption and scattering."

Following the link for absorption got me here:

http://en.wikipedia.org/wiki/File:Atmospheric_electromagnetic_opacity.svg
"File:Atmospheric electromagnetic opacity.svg"

Does that figure help?

Last edited by a moderator: May 5, 2017
3. Apr 27, 2012

### D H

Staff Emeritus
Re: At what altitude does a solar panel see a noticeable increase in wattage/cubic me

Only because that 12km altitude is still in the stratosphere. Once you get above the stratosphere you essentially have unfettered full sunlight.

4. Apr 28, 2012

### OtherRealm

Re: At what altitude does a solar panel see a noticeable increase in wattage/cubic me

Just using the key words insolation versus altitude has given a few more relevant results (goes to show that having the right search terms in research is key), but I have not found any hard numbers for solar wattage at the top of the troposphere (I mistakenly used thermosphere in my first post). Does anyone have weather balloon data or something of the like and measured insolation levels at this altitude? Thanks.