Solar charging a smartphone is easy, but there are so many products on the market making promises that it becomes difficult to choose. The purpose of this article is to clear it all up for you.

First, I will tell you what to look for in a solar charger. Second, I will cover a few issues with a simple QnA. If you still have questions after reading this article, please send me an email.

What you’re looking for in a solar charger…

1. POWER OUTPUT
Most smartphones these days will not accept power from any USB port not able to provide at least 1,000mA. Do not accept any charger that isn’t USB 3.0 or better. A tablet-friendly USB charger is capable of 2100mA maximum output, and this is preferable to anything less. Don’t worry… your device won’t blow-up just because the port is capable of higher output. Your device is in control of its own charging, and will accept the power it needs.

2. POWER STORAGE
A smartphone holds approx 6 Watt-Hours of power (1400mAHr). Due to losses in the charging process, this means your solar charger will need to provide at least 8 Watt-Hours (2200mAHr) of power if you are charging your phone from a completely dead state.

3. SOLAR POWER
In my experience, if a solar charger product is not able to charge itself from a completely dead state over the course of two summer days (or faster), then it is a weak design. For example, I would expect to see nothing less than a 1 Watt solar module on a charger with a 2200mAHr storage battery inside. It makes no sense to wait 4 days for a full charge from sunlight.

4. PORT COMPATIBILITY
USB ports are supposed to be standard, and yet I constantly see smartphones reject certain ports for one reason or another. So, I have come to rely on one simple test that removes the frustration: Apple compatibility. Even if you are using the latest BlackBerry or Android, if the solar charger says it is compatible with the fussiest USB products around (ie Apple), then it will usually work for you.

Now a little Q&A…

1. Can I plug into the charger anytime, or do I have to wait until it is charged?
Plug in anytime.
Some solar chargers will stop charging themselves from sunlight while you charge your smartphone, while others will use both the solar output and their internal battery to charge your device.

2. Can I go straight from a solar panel to my smart phone?
Not usually. The reason relates to point #1 above. If the panel is not able to provide upwards of 500mA at any given time, and preferably 1,000mA, then unlikely that your phone will acknowledge the solar panel’s existence.

3. How many charges will I get each day from the solar charger?
A typical 0.5W/2200mAH solar charger will be able to keep up with 25% usage of your smartphone (summer, with good daily exposure). Twice the solar panel will provide twice the power offset.
If all you want is a back-up battery with a cool solar add-on, then I advise getting a battery capacity of at least 2200mAH so you can charge your phone fully one time (or from 50% down twice). If you are a heavy smartphone user, then get a battery capacity of at least 4000mAH.

4. How long do these chargers last?
If you take care of it, and don’t completely drain the battery on a regular basis, then a typical lithium-based battery will operate properly for several years. Stick to solid names like Powerfilm, Brunton, Eton, Voltaic, and others to ensure that you are getting the highest quality components in your charger.

I look forward to your questions!