This build uses a custom 3D-printed / hand assembled case from RPi hacker Cottonpickers, which comes attached to the back of a 300mA solar panel. The case includes a…

* Switch so you don’t have to keep pulling the lead out to swich it off (but switching it off won’t stop the batteries being charged)
* Blue LED so you can see when the batteries are being charged by the sun
* USB Socket so you can charge other USB devices like phones. Add $5 or £3 if you need added Apple circuitry to charge ipods/phones/pads
* USB Lead, so in winter you can just plug the lead in to a USB socket to charge the batteries (won’t fully charge them this way) and run the pi when the batteries are flat and theres no sun

4 × AA NiMH rechargeable batteries provide reserve power. Once you’ve got your Pi running on sunlight, David Hayward over at CNET UK will show you how to configure the Pi so you can access an external hard drive attached to one of its USB ports via FTP. Check the link, below.

How to make a Raspberry Pi solar-powered FTP server | Reviews | CNET UK