This is what we use ourselves when we're far away from the office - a solar power laptop / notebook charger, complete with storage battery.

The solar cells when folded have a footprint of just 220 x 150mm, making it a perfect, lightweight companion for even the smallest of notebooks. They can charge most notebook computers in 3 to 4 hours.

The storage cell is a high capacity Lithium battery, useful independantly of the solar cell as an additional notebook battery. It can also be charged via DC.

Both units pack together in the built-in carry pouch provided.

Specifications:
Solar Cell Output: DC / 18v @ 1.2A
Storage Cell Output: DC / 15v~24v @ 3.0A