CNET has the instructions for setting up your mini FTP server. With it, you can access your digital files from anywhere 24/7—and the solar panel means your electricity bill won't be affected at all.

Well, you get the crazy sort of DIY project I love to see. This thing is basically a 3D-printed case with a battery pack/charger combo run by sunlight and a Raspberry Pi set up as an FTP server.

Password: raspberry, replace this with user's password (if other than pi). With luck, you should now have access to the external USB hard drive, via FTP, internal to your own network.