Nick Jones

In past blogs I have commented that I am deeply unimpressed by mobile devices with solar cells for charging. My suspicions about the effectiveness of these devices have been reinforced by a test and teardown of the Sharp SH002 reported by TechOn. The reviewers of this device found that it took 60 minutes to charge up 3 minutes of talk time. That equates to 20 hours charging for an hour of talk time, and given that most of us don’t get 20 hour long sunny days this means leaving your phone in the sun for two whole days for an hour of chat. What’s the use of a mobile phone that spends most of its life sitting on a sunny window ledge charging up? Mobiles need to be in your pocket to be useful. Can we maybe imagine the need for a new voicemail greeting: “Hi, Nick is unable to answer the phone because it’s basking in the sun charging up and he’ll be unable to speak with you for another 20 hours. I hope the inconvenience is partly repaid by the knowledge that you’re saving the planet”.

But in fact you’re not saving the planet. The hidden problem here is the embodied energy. I.e. the energy taken to manufacture the solar cells and supporting electronics; this also generates a CO2 debt which will likely never be repaid during the life of the phone because the solar charging is so ineffective. So not only are buyers of the phone paying for an ineffective feature, they’re also deluding themselves if they think they’re being green, because the embodied energy debt makes a solar handset less environmentally sound than a well engineered conventional handset with a modern charger. As far as I can tell it’s just greenwashing. And if any handset manufacturer reading this believes I’m wrong please send me the calculations and I’ll be happy to share them.