Best solar phone chargers, and ones to avoid

Some types of solar phone chargers can actually shorten your battery life. Here’s how to choose.

If you frequently experience the frustration of a smartphone that’s running out of juice and having nowhere to charge it, you should consider a portable solar battery charger.

These portable devices range in sizes no larger to a smartphone case, to larger folding chargers with multiple panels that can supply enough power to charge a tablet or even a laptop.

Your product choice will depend on the type of device you want to charge, how frequently you need to charge, and whether you need power delivery even after the sun has gone down.

Before listing some recommended models, let’s first take a look at some devices that you should definitely avoid.

Don’t buy solar cellphone cases

There is one type of solar phone charger that you should not use, which are phone cases with solar panels built into the back. Here’s an example:

The reason is that heat will shorten the life of lithium-ion batteries, and if you use solar smartphone chargers the way they intend, you will be subjecting your phone to a lot of heat that can damage your phone’s battery and permanently reduce it’s maximum capacity.

As you can read in this Battery University article, lithium-ion batteries like to be cool. Temperatures above 85F will start to stress a battery, and going much higher than that can severely stress the battery and shorten its capacity.

If you look at how they solar phone cases are designed to be used, they are bound to generate a lot of heat.

First, they wrap around your phone, helping to hold in heat - but that alone isn’t so bad, because that’s what all phone cases do. But to charge your phone, you put your phone face down in direct sunlight so the solar cells on the rear of the case can charge your phone.

The effect of putting your phone in direct sunlight, even if it’s through a window, will heat up your phone quickly. On top of that, you’re now also charging your battery, which results in additional heat. Finally, the wraparound case helps to hold the heat in.

In other words, you’re basically cooking your phone with these devices. They’re bad for your battery. Don’t use them.

Solar chargers you should choose

The best type of solar chargers are either:

  • A large, folding solar charger with multiple panels. These will allow you to either form a tent over your phone while the panels stay in the sunlight, or let you plug in a charging cable long enough that you can leave the charger in the sun while keeping your phone in the shade.
  • A solar panel-battery combo that includes both solar panels and a large battery. This will allow you to charge the storage battery any time you want, freeing you to charge your phone later, even when the sun isn’t shining. While you could purchase an external battery and a solar charger separately, an all-in-one design is more convenient.

In terms of the latter, you can find compact solar panel-battery combos that have only one small solar panel. These should be avoided, because one small solar panel isn’t going to generate very much wattage - barely enough to keep your phone topped up, let alone charge one that’s deeply discharged. If you need something that compact, it’s better to just get an external battery and skip the solar charging altogether.

With that out of the way, here’s some solar chargers that are highly recommended:

BigBlue 28W Solar Panel with 3 USB Ports

  • High efficiency (21.5-23.5%) flexible SunPower cells
  • Two USB 2.0 ports and one USB Type-C port
  • Large 28 watt power output
  • Moderate (IPX-4) water resistance
  • Has four panels that folds up into a compact package

The BigBlue is a great choice because the 4 SunPower solar panels gives it a large enough output to charge larger devices such as a tablet or Chromebook. In addition, it has both older USB 2.0 and newer USB Type-C ports. The advantage of USB Type-C is that it has a higher output voltage, resulting in faster charging for devices that support it.

The use of flexible monocrystalline SunPower cells is a good choice for this type of device because of the high power output. Other portable chargers may use thin-film solar, which has the advantage of being very flexible - even rollable - but at the cost of lower efficiency. These cells have the same efficiency as SunPower home solar panels, but in a flexible format.

Note that these types of cells are only partly flexible. They can withstand about a 30 degree bend, but anything more that that risks damaging the cells. This means that this charger should be stored flat, and not jammed at the bottom of a backpack where it could get damaged.

X-DRAGON 40 Watt Solar Charger

  • High efficiency (21.5-23.5%) flexible SunPower cells
  • Two USB 2.0 ports and one 18V DC port
  • Large 40 watt power output
  • Includes adapters for direct charging of common Windows-based PC laptops

If you have large power requirements, such as charging a laptop, this X-DRAGON charger with eight SunPower cells is the one for you. With 40 watts of output, it has enough power to charge a smaller Windows laptop or Macbook Air when used in full sunlight. For Windows laptops, it has an 18V DC output and a selection of charging adapters that are compatible with the most common Windows-based laptops. This is a great feature for laptop owners, because the higher voltage means more efficient charging.

It also has two standard USB ports that you can use to charge smartphones, tablets, or a newer Macbook (with a USB Type A to Type C cable).

Like the BigBlue, the X-DRAGON uses flexible monocrystalline SunPower solar cells. This means that while the cells can be safely bent up to 30 degrees, you should store this device flat to ensure that the cells don’t get damaged.

The tradeoff for the large power output of the X-DRAGON is that it’s a pretty chunky device. Folded up, it’s shorter and narrower than a sheet a paper, but more than 2 inches thick.

But if you’re frequently outdoors and have hefty charging requirements, a solar charger large enough to supply your power needs will be beefy. The X-DRAGON, with its eight monocrystalline panels and a 4.2 star rating on Amazon, fits that bill nicely.

SOARAISE 20,000 mAh battery bank with 3 solar panels

  • Very large 20,000 mAh battery capacity
  • Two USB 2.0 ports with 2.1 A output
  • 3 solar panels with 4.5 watt combined output
  • Integrated wireless Qi charger
  • Integrated flashlight

Sometimes you want to be able to charge your devices even when the sun isn’t shining. This combo solar panel charger/battery bank does just that. With its huge 20,000 mAh capacity, it’ll charge even the largest smartphones or tablets multiple times before being drained. It has three solar panels, which makes it a better option than other solar battery banks that include only one small panel.

It includes two USB ports with 2.1A output, and also a Qi charging pad for wireless charging.

The package is integrated with 3 fold out solar panels. SOARAISE doesn’t list the type of solar cells, but the combined output is only 4.5 watts, so it’s using lower quality cells. 4.5 watts is enough to charge a phone in full sunlight, but fully charging the battery bank will take multiple days. Still, that’s enough to save you in an emergency when the main battery is dead.

This device is best used by fully charging it via the USB port before leaving home, and using the solar cells to keep the device topped up.

Why no thin-film solar chargers?

You might have noticed that thin-film based chargers aren’t on the list.

Thin-film solar panels use a different chemistry than the more common crystalline silicon panels used in these devices and on the solar panels that you find on homes. The different structure and manufacturing of thin-film solar allows them to be extremely flexible, even completely foldable as a sheet of fabric.

There are a few thin-film portable solar chargers on the market that roll up into a neat package. So why aren’t they recommended?

Two reasons. First of all, they’re more expensive. Because crystalline silicon is the chemistry used for solar panels in homes and utility power plants, the manufacturing volumes are much higher, resulting in lower prices. The simpler manufacturing process of thin-film cells means that they could be potentially cheaper, but they remain a niche product with much lower manufacturing volumes, which means they remain more expensive.

The second reason is lower efficiency. The SunPower cells used in the BigBlue and X-DRAGON are among the highest efficiency cells on the market, which means that they can deliver more power in a smaller package. While thin-film chargers can be rolled up, when deployed they need a larger surface area to achieve the same wattage. This is less convenient for the use cases that are typical for portable chargers, like hiking and camping.

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