Recharge your MacBook air with solar energy

Quickertek already offers 802.11n products for your Mac, and has now announced a solar energy recharge system for the MacBook Air.
The system comes in 3 versions (18W, 27W and 55W), allowing you to charge your MBA in 14 hours (for the 18W model), or even 5 hours (for the 55W model). The only thing that might keep you away from buying it is that you need quite some space, and... quite some money: the 18W version is a 30" surface, and costs $500. The 55-watt model costs $1000, and requires a surface of 60x42", or about 152cm x 106 cm.
Let's just hope that the capacity of these solar cells will increase soon, making it possible to put such products together with your laptop in the laptop bag.