Use Goal0 Nomad 7m Solar Panel to charge MacBook Air? I've got a Goal0 Nomad 7m solar panel. It produces ~7 amps @ &lt;22V DC on a regular day.

The MacBook Air has a 45W charger. The markings on the charger say it runs at 14.5V DC @ 3.1 amps. Unless I'm wrong (and I may be, I'm only a beginning EE student ;) those numbers are smaller than the ones on the output of the solar panel. To confirm it another way, P=IV, (P is power in Watts), so theoretically P=7*22=154 watts. 154>45.

The Nomad 7m has a 12v cigarette-lighter style outlet that will fit the MB Airline Adapter. The problem is that it puts out 12v (or so it says, but I'm hoping it's actually around 14) and the Airline adapter needs 14-15 to work right.

What do you guys think? Is this possible? Any recommendations for alternative options (I could always use a 3rd party vehicle adapter if need be). If it puts out this much juice it should also be able to charge a regular MacBook, I think.
If you look at the page for the Goal0 Nomad 7M (click "Tech Specs") It's rated for 7 Watts. 

I don't where you got the "~7 amps @ &lt;22V DC on a regular day." 

So the sort answer is - That panel won't even keep the MacBook Air running at idle, let alone charge the battery.

Your post got me curious, so I broke out a Kill-A-Watt power meter.
11" MacBook Air Power Draw, battery already fully charged, measured at the wall:


Idle, screen backlight completely off: ~4.7W
Idle, Minimum Screen Brightness: ~4.9W
Idle, Half Screen Brightness: ~5.4W
Idle, Maximum Screen Brightness: ~8.0W


For the active tests, I have the screen set to half-brightness, where I usually use it:  


Moving the mouse in circles with the trackpad: ~6.5W
Scrubbing the Dock (with magnification): ~11.2W
HD Video Decoding, GPU accelerated: ~15.6W
SD Video Decoding, GPU Accelerated: ~11.2W
Flash SD Decoding (not sure if it's accelerated): ~12.7W


Ok, these figures are VERY approximate (the Kill-A-Watt is not a high precision instrument), but they do put things in the ballpark.



The theoretical approach -  

Insolation is the term for the amount of energy that falls on a set area per set time.
Basically, we can calculate the amount of solar energy which falls on a specific area.
The Photovoltaic array wikipedia page gives us a ballpark figure of ~1Kw/M².  

Then, you have to take the efficiency of the Photovoltaic Panel into account. 

Wikipedia gives us a best-case mono crystalline panel efficiency of ~25%, shich means that only 25% of the light which falls on the panel is converted to electrical energy, while the rest is dissipated as heat, reflected away, etc...

Therefore, a 1m² panel will, at the equator and with a mechanism that points it directly at the sun, manage ~250 W.

From this, we can tell that a 154W panel would have to be ~0.616 m² (154/250 = 0.616), far larger than what you have.

Examining the 7W panel you have - How big does a panel have to be to produce 7W?

7/250 = 0.028 m², or 280 cm² or about 14*20 cm, which seems pretty accurate, judging from the pictures on the product page.



Anyways, I went of on a bit of a tangent here, because you mentioned you're an EE, which is one of my main interests.