Frostfire have released a battery ‘backpack’ (or sled as they used to be known) for the iPhone 4 that includes a solar panel for charging. Called “Mooncharge” you can simply flip your iPhone 4 over and let the sun recharge the internal battery, which in turn will recharge your iPhone. If you live in the UK you can rest easy as the mooncharge also can be charged via a conventional USB connection.

“This unique and innovative case will power your iPhone for an extra 315 hours on standby and provide up to 27 hours more music, 10 hours more video and 5 hours more talk time.”

This isn’t the first solar powered battery charger we’ve seen, but it is the first specifically moulded into an iPhone case, and the charge time looks impressive. Anyone bought one who’d like to confirm performance?