Q. I’d like to get a good cellphone solar charger. I just got a fairly inexpensive one, and to be blunt, it sucks. Are there any good ones on the market for less than $100?

Jim R.
Ann Arbor, Mich.

A. Dearest Jim,

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My sympathies to you and your less-than-satisfying solar experience. But I’m cheered to know it hasn’t left a black cloud over your head when it comes to this technology – harnessing the sun’s rays to power your next session of Fruit Ninja is still a bright idea. As you’ve so recently been reminded, sometimes you do get what you pay for. Fortunately, I’m confident those 100 smackers can get you a perfectly pleasing device.

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That said, let’s make sure to have reasonable expectations for today’s chargers. They won’t juice up your phone as quickly as an AC wall outlet will. In fact, it’s pretty typical for a solar charger to take a whole day to convert sunlight into power, and then several hours to transfer that to your phone. And depending on a model’s design, they might struggle in low-light or cloudy conditions. But once you get your system down – setting the charger in the sun all day, charging your phone at night, perhaps – they can take your chatting totally off the grid. I’d say that’s a pretty sunny outcome, even if it does take a bit longer.

Speaking broadly, there are two main types of solar chargers for gizmos like cellphones, tablets, and mp3 players. One kind charges up a portable battery, which you then use to recharge your device at your leisure (usually via USB). The other charges your phone directly, without the battery middleman. While the latter can be convenient for topping off on the go, I’d recommend the battery type for you, Jim. They allow you to charge your phone even when it’s dark or cloudy (something I imagine you’re familiar with in those Midwestern winters), for one. And you can leave them baking in a sunny spot all day rather than toting them around with you, which is nice if you choose a heavier, bulkier model.

So which way thence? Consider a few more features. One, surface area: The larger the solar panel, the quicker it will transform sunshine into battery power, and the better it will be at wringing juice out of overcast skies. Smaller chargers come in around the size of your phone, while bigger panels can be four feet long or more. Shape also matters: These intrepid testers found that stiffer panels with sturdy bases are best because they can be propped up to gather maximum rays, no matter where the sun is (other models must lie flat on the ground, losing out when it’s not high noon).

Also look at the solar charger’s watt rating. The higher the watts, the faster the battery will power up your phone (by a factor of several hours). Phone-appropriate models are typically in the four to seven watt range, though you can find chargers up to 27 watts (and a $1,000 price tag, I should add). And finally, I’d lean toward a charger that uses USB to power any device, rather than one that demands specialized, fussy cords for every gadget.

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I like to keep things brand agnostic over here, Jim, so I hesitate to endorse any one product over another. Plus, I haven’t personally tested the bevvy of solar chargers on the market against each other. But plenty of other smart people have, and I do feel comfortable pointing you to their recommendations, many of which come in at $100 or less.

Take the Cobra CPP 300, winner of the Wirecutter’s head-to-head review: The battery pack gathers sun efficiently and charges up quickly, and can power two electronics at once, for a cool $80. Good Housekeeping gave the crown to the Fat Cat Solstice 2.5 for its powerful battery and multidevice compatibility ($100). And the folks over at Outdoor Life ranked their top seven models, four of which come in at or under your price point. All of these reviews include plenty of runners-up, too, so you should have plenty of options to get you started.

Happy shopping, Jim, and may your skies always be sunny.

Radiantly,
Umbra