The advantage of using a wirefree solution such as PiJuice compared to the thousand external power packs already out there is that the PiJuice is integrated and convenient, just like the power supply for a mobile phone or laptop. You can plug it in and out of any of your Raspberry Pi project at any time, quickly and easily without having to use cables and bulky batteries.

The PiJuice is compact, cost effective and ideal for all portable applications such as building Raspberry Pi robots that require a small and compact power supply. The PiJuice's lithium ion battery gets you 24 hours of power, though the module is compatible with a larger 5000 mAh battery for even longer battery life. 

One of the the most appealing features about the PiJuice is the solar power option that allows you to literary power your Raspberry Pi forever, thanks to a specially made 6V solar panel for plug and play remote operation.

PiJuice is compatible with all current Raspberry Pi models (Raspberry Pi A+ Raspberry Pi B+, Raspberry Pi 2B) and includes a GPIO header extension, full power management API, integrated Real Time Clock (RTC), Uninterrupted Power Supply (UPS), Wake On alarm, low power deep-sleep state and multi-colored RGD LED among other features. The PiJuice provides a neatly packaged portable power solution to power the Raspberry Pi via battery and solar power.