Let's get this out of the way right up front: The SolarTab is the best solution I've seen for using solar energy to charge your gear in the wild. The problem is, with the ubiquity of cheap, high-capacity external batteries, I'd pretty much written off solar chargers as obsolete. But more on that later.
A Bright Spot in Solar Charging
The SolarTab combines a high-capacity 13,000 mAh battery with a 5.5W, mono-crystalline silicon solar charger. The "mono" part is important. Older solar chargers use poly-crystalline panels—the ones with that fish scale look. Mono-crystalline chargers are much more efficient at turning light into energy.
The company says the SolarTab's turns 21 percent of the sunlight it receives into energy; that's right near the top of the charts for consumer-grade -- even residential -- panels. Commercial grade and "concentrator" panels have higher efficiency, but you wouldn't want to carry them around, even if you could afford them.
It's also the best packaged solar charger I've seen. You'd be forgiven for mistaking it for an iPad -- its dimensions are almost identical, and in its protective case, it's a dead ringer for one. This makes it a breeze to slip into a backpack or travel case -- if you can fit your iPad, you can fit a SolarTab. It's a sleek, slim alternative to the traditional canvas, foldable solar chargers that dominate the market.
The case doubles as a stand, allowing you to adjust the solar panel as needed to get the most direct angle to the sun. That's important too: efficiency is significantly affected -- obviously by how much sunlight reaches them, but also by how direct that sunlight is. When not in use, a Moleskine-type elastic band slips over the cover to protect the solar panel.
Any more bright ideas?
In our testing in bright, direct sunlight, the SolarTab charged fast enough to maintain its charge while charging both an iPad Pro and an iPhone 6s through its two USB ports -- something no other solar charger we've tested has been able to do. In about two hours, the SolarTab increased the iPad's charge by about 20 percentage points, and topped off an iPhone that had a 60 percent charge when it was plugged in.
The company says the SolarTab will charge an iPhone 6 in 1.5 hours and an iPad Air 2 in four, which seems in line with our testing. That's mostly because it's charging devices from the battery and not directly from the sunlight it's receiving.
Bear in mind that's not the best way to charge your devices. Unsurprisingly, both devices got very hot sitting in the bright sun. We slipped the iPhone in the space between the SolarTab and its case and covered the iPad with a towel. But in real world use, it's much better to use the sun to charge the SolarTab's battery, and then use the battery to charge your devices later. (Preferably when you get back to camp after a long active day on the trail.)
Oh, and please don't strap your solar panels to your backpack while you hike. You'll look silly and will almost never get enough direct sunlight for practical charging.
The SolarTab sports a large LED on its side that lets you know the solar panel is generating electricity. The brighter the light, the better the charge. It also has four smaller LEDs that—with a push of a button—light up to let you know how full its battery is. It has two USB ports for charging devices and a microUSB port that allows you to charge its external battery by plugging it in to power. (Always a smart idea before taking it out on a trip.) All ports also have an LED charging indicator light.
Has Solar Been Eclipsed by Battery Technology?
There's almost nothing not to like about the SolarTab. The biggest question is the one I promised to get to at the beginning of this review: In a world where external batteries are cheap and plentiful, do we need to worry about charging things in the field anymore?
To that I'd say "it depends." There are more use cases for chargers than camping and hiking. For that matter, there's more than one way of camping and hiking. If you're going on a weekend camping trip and don't intend to use your phone to do more than take a few pictures and call home at night, then you're much better off packing a much smaller external battery. You can find some on sale for under $20 that match the SolarTab's 13,000 mAh capacity. Granted, you won't be able to recharge it while you're in the field—but you almost certainly won't need to.
So who's the SolarTab for? If your trek takes you out longer, or you have more devices (a GoPro or other camera, Bluetooth speaker, your spouse's or kids' devices) that you'll be putting to more use (as a GPS receiver, for Geocaching, taking movies, etc.), the SolarTab starts to make a lot of sense.
Good Day, Sunshine
The SolarTab could also be tremendously useful in other situations. As a longish-term solution during a power outage, on a long trip in a car without enough chargers, to drive a wireless speaker at a picnic or outdoor barbecue...once you start thinking beyond the traditional weekend camping trip, the possibilities really start to add up. I've even used the SolarTab on business trips, to power my devices without having to unplug a bedside lamp or crawl behind a night table.
Even at its current sale price of US$97, the SolarTab isn't cheap if you just compare it to external batteries. (Its original list price is US$130.) But if you look at standalone solar panels, which don't usually include an external battery, the SolarTab is a relative bargain and far less bulky. It even comes with a MicroUSB cable and wall charger—something that's no longer a given with tech gear.
The Bottom Line
Cheap external, rechargeable batteries mean that off-the-grid charging solutions aren't necessary for everyone anymore. But if your activities take you beyond the range of an external battery alone, the SolarTab is an efficient, attractive, highly portable way to keep your gear running when there's no place to plug it in.