[Update: Apparently, the company no longer sells these solar chargers]
When I first saw the Changers Solar Charger, I was excited about the idea, and I’m not alone. After I had already tried a few small solar modules without success, this system actually seemed to work. Climate-neutral production is another bonus point (but you need credits for it, see below). Personally, I don’t need the connected community, but bragging about your own energy-saving performance is certainly more useful than any cat content. I also don’t need some kind of payback functionality with credits for top-ups, but it’s probably an incentive for some. All in all, a good idea. Or?
In principle, yes. But the effect is rather in the minus range. The solar module with battery costs around 150€. One kilowatt hour costs 27 cents rounded up at our “green” electricity provider Lichtblick. Let’s assume 2 charging processes a day (2 mobile phones in the household, I charge more than once a day, but then on the go), and we assume that the mobile phones are completely discharged every time (unrealistic, but easier to calculate and to the advantage of Changers). The battery of the iPhone has a battery capacity that allows a consumption of 0.0055KWh. Then we come to 2.0075 KWh for 365 days, which corresponds to 54.21 cents rounded up. With 2 mobile phones we are rounded up at 1.09€. In the year. Not per day.
We are even more precise: A charger consumes more electricity than it passes on to the battery, one speaks of about 70% efficiency. For the sake of simplicity, let’s pretend that only half of the power reaches the battery, again to the advantage of Changers. Then we would be at 2.18€ per year. We can now assume for fun that my Nexus 5 consumes twice as much power (it doesn’t), to the advantage of changers. So how many years would you have to use the solar module every day for 2 charging sessions to make it profitable to save electricity, if it actually managed to charge 2 times at all, even in winter? I doubt that the module and the battery will last that long at all. In purely mathematical terms, we are not doing the environment any favours here.
Ok, this is not just about saving electricity. But also about saving CO2, instilling an awareness of the general public about saving electricity, etc. But then you shouldn’t hide the fact that the transmission of the savings data requires WIFI, which in turn consumes electricity, and the community on Changers.com’s servers also consumes electricity. I have the impression that more work is being done here with the do-gooder feeling than with an actual environmental relief.
By the way: A refrigerator consumes hundreds of kilowatt hours per year. Buying a more efficient device can cut electricity consumption in half. In this case, the return on investment is there within a few years, not decades or half a century as with Changers. Leaving the car at home probably also helps the environment more than this solar module in 10 years. However, it’s not as convenient, and you can’t brag about it as well as in the Changers.com community.