Solar-powered power banks seem like a fantastic idea; attach some solar panels to a power bank, and you have a free power source whenever the sun is shining.
However, the reality is different from this idyllic vision of limitless energy.
Someone tested nearly two dozen solar-powered power banks, ranging from devices purchased online to ones bought from camping and outdoor supply stores. Unfortunately, every single device has been disappointingly ineffective — and some have even been potentially dangerous.
Using such a device means placing a power bank, a box filled with lithium-ion batteries, in direct sunlight. And that’s a big problem. I’ve found that a power bank left in the sun on a modestly hot day can hit temperatures as high as 80°C/176°F, which is incredibly hot for lithium batteries.
These temperatures came after the power bank spent 10 minutes in the sun.
Not only do those temperatures push the devices to a dangerous area, but those heat levels mean the charge controller is likely to prevent the batteries from charging, which defeats the purpose of leaving the power bank out in the sun.