Those of you with very good memories might remember Kyocera showing off a solar-powered smartphone display at last year's Mobile World Congress. Well, the company has returned in 2016 with a much-improved prototype, and says that this type of technology could start appearing in consumer phones in the near future.

The Kyocera rep we spoke to on the show floor in Barcelona couldn't be any more specific than that, but he did say the tech is almost ready to go, and much closer to officially launching than it was in 2015. It uses a 0.55 mm-thin pane that sits between the display and its touchscreen layer, giving you a battery charge that equates to 1 minute of talk time for every 3 minutes of direct sunlight – that's an 8x efficiency improvement from the demo model Kyocera brought to MWC last year.

French firm SunPartner is responsible for the solar-soaking panel, which is called the WYSIPS (What You See Is Photovoltaic Surface). SunPartner says the "design-neutral" component can work with any type of phone: Kyocera itself specializes in rugged, outdoor handsets, but the chunky case you see on the phone in our hands-on pictures is nothing to do with the solar charging.

Kyocera's MWC team told us that the company envisages these phones being used by those working outdoors or on remote sites, as well as anyone else who's going to be away from a power source for an extended period of time (think campers or skiers). The technology isn't (yet) designed to replace your wall charger – it's not fast or efficient enough for that – but it will keep your phone topped up in standby mode and give you an alternative emergency charging option if your mobile dies far from home.

Another area where Kyocera and SunPartner have improved the technology is in the display's transparency. The darker (less transparent) the panel, the more efficient it is at converting sunlight into energy, but you'd quickly lose sight of your apps and incoming emails. At 85 percent transparency, Kyocera and SunPartner think they've found the right balance between visual appearance and charging performance.

We had a quick look at the prototype 5-inch Android handset at Kyocera's MWC stand and unless you were looking for it you'd be hard pressed to notice the screen was darker at all. The extra photovoltaic layer has no effect on touchscreen responsiveness, and adds virtually no heft or weight either. It feels like any other smartphone.

The same technology can be applied to smaller or larger screens too (up to 13 inches) and so it's likely to find its way into smartwatches, tablets and other devices too. What's more, it can work even if just a third or a half of the screen is in sunlight.

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