Battery life is a constant issue with modern smartphones. A phone with better features has to be bulkier, requires a larger battery and drains more power. Wirelessly powering a phone at a distance is a technology in development facing several issues that hamper its commercial reality.

Recently, Kyocera demonstrated a concept phone at the Mobile World Congress 2015 that used a novel, transparent solar cell technology to extend battery life. The concept phone uses an added layer in the cellphone’s screen, the Wysips, from a company called Sunpartner. The 0.1mm-thick transparent layer can supply up to 5mW/cm2 in peak conditions without impacting the touchscreen’s functionality. Sunpartner also expects to double the power output in the near future with more efficient solar cell technology.

While this is not even close enough to power a smartphone fully, the technology can power a phone on standby mode as long as it is in direct sunlight. This could potentially be valuable now particularly in outdoor applications, though use in smaller mobile devices seems ideal. Kyocera’s concept phone was a ruggedized device made for outdoor use.

Unfortunately, the technology is not sufficiently efficient to work on mobile devices with screens of less than 3 inches. This spells bad news for smart watches, the mobile device class at the moment with the worst battery issues. Nevertheless, with sufficient advances in solar cell efficiency, wearables and IoT devices could potentially be powered using the technology.