Window-mounted solar chargers

Wendy S. Delmater
By Wendy S. Delmater on Tue, Jul 21, 2015 - 10:45pm

This is just a heads up - I saw this at Interesting Engineering: they now have window-mounted solar chargers for devices. My guess is these were not practical until photovoltaic cells became much more efficient like they are today.

Here is a page of them. This is not an endorsement, I do not own one but they look interesting.

1 Comment

silvervarg's picture
silvervarg
Status: Bronze Member (Offline)
Joined: Mar 28 2010
Posts: 57
Varying quality

There is lots of packages to charge phones etc from, and the quality varies from total crap to really good.
Since I have looked into this a bit and tested a few devices (and read lots of reviews and user comments) I would like to give my 2 cents.

Generally we see 3 types of devices:
Solar panel only with no battery. Made for direct connection to cellphone etc. Generally these are specialized for hikers that want high quality gear with low weight and long durability. Expect to see a high price tag and a known brand name, like Brunton.

The second device is the combined small solar panel and battery. In general the solar panel is really small, so it takes a huge time to charge up the internal battery.
Often there is an option to charge from USB, and it is there because the solar panel is far to weak to be really useful.
Price is often low, way less than you pay for a s decent device without battery.
I personally own 2 of these devices and both are pretty crappy.
My advice is to stay away from this category.
Generally they don't list the output power from the solar panel, but the size we see on typical devices are about 0.5W. A normal charging power for a cellphone is 5W (1A at 5V). With a 0.5W panel with losses in charging electronics and battery it will take a full day in bright sunlight (if placed outside) to get enough charge to make 1 hour charge of a cellphone.

Third is the devices that are just a battery that you charge from USB. As the tiny cheap solar panel is almost useless by ditching the solar panel it can be made slightly smaller and much more robust. Quality on these varies a lot, but in general that are much better quality than the combined versions.
I own 1 of these devices and it is really good. Brand is a T with there S turning around the top of the T like if they where winds on a windmill.
It is really simple, but a quite rugged design that works really well. It got two ports out but max output current is 1A. Good for charging a phone, but will take a long time to charge a tablet.
I also got an emergency charger that you can put regular AA batteries in to get a portable USB port. Only intended for real emergency charging.

In general a device that will be decent to charge a tablet will be bigger and heavier so not a great option to carry around it you just need to charge a phone or other smaller device.

If you do get the combined solar+battery despite my recommendation no to be careful with how you set it up.
If you have it attached with suction cups to a window and connected to you phone and the suction cups comes loose there is a good chance that the charger drops down to the floor and pulling your phone with it (as it is attached with a cable). There is a good chance to destroy both charger and phone at the same time.

And one last point. There has not been any really dramatic increase in solar power efficiency, at least not in the commercial market. Some really advanced solar cells have been made to beat records, but so far I have not seen any of them available to end consumers.

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