Utility power is out and your phone battery is draining down to zero. Your next obvious choice is to start your car or home generator and use their charging capabilities to keep your phones up and running. This will work just fine for a period of time but what if power is not coming back quickly and your gasoline supply dwindles. A compact foldable solar panel, stored inside your bug-out bag, can emerge to be your best friend (solar phone charging).
You need a simple and ready to go, back-up plan. An excellent standby small power source capable of charging your phone is a compact, affordable, and portable solar panel. There are many choices on the market so you are in luck.
Solar Panel & Phone Charging Basics
Here are the basics. A solar panel converts sunlight into direct current (DC) electricity (the type used by your phone). Most foldable panels include a voltage regulator circuit and USB ports to support easy plug-in phone charging. Exposing the panel to strong sunlight (few or no clouds) for several hours will provide the ideal charging conditions to charge a phone battery. Of course it will not work at night, mostly cloudy or rainy days, but for most locations there will be enough sun on average to make this a viable back-up.
My experience shows that you need a 20 watt minimum solar panel for an effective solar phone charging solution. The rated panel wattage is the best the panel will produce under ideal sunlight conditions. Most phones need a USB port capable of providing 2.4 amps at the standard 5V USB output to charge, which equates to about 12 watts of power. Inefficiencies (losses) are unavoidable in the solar power and charging system, so you must start with a panel that has a wattage capacity rating which is more than the phone requires to charge.
Larger size solar panels are available to satisfy even higher power demand devices like tablets, etc. but the panel size grows directly proportional to the solar panel wattage rating. Panels with a capacity of 20-24 watts are in the “sweet spot” balancing capacity, bulkiness (size), weight, and cost. Note that these portable panels are moisture resistant (not waterproof) so keep them in a dry storage location when not in use.
Foldable Solar Panel Recommendation
I purchased a 21 watt Anker foldable solar panel in 2021 that has worked well for me. There are several other Anker products (flashlight, charging cables, etc.) and have been impressed by their durability and reliability. I know there are other very good products on the market, but in my mind Anker designs and manufactures high value products. For the record, I have no association with Anker, but simply like their products.
Tips for Maximizing the Charge
Some portable solar panel users (like campers), lay their panel flat on the ground in the sunlight. This works but a better technique is to angle the panel so it’s directly facing (perpendicular) to the sun. Prop the panel on a box or equivalent to gather as many rays as possible. If you are able to and in dire need to obtain every “ounce of charge” in emergency situations, you can reorient the panel several times during the day to follow the sun across the sky.
First Try Charging One Phone at a Time
Keep in mind that the total available charging power will be split equally between phones if you connect more than one phone to the USB charging ports. Connections are made to each phone through a standard USB cable. Obviously your phone will need to be close to the sun bathed solar panel but keep your phone shaded to avoid a possible overheat condition, especially in the summer months. A piece of cardboard will do the trick. If your solar panel has sufficient capacity to fully charge all phones simultaneously, that’s great. But many times that will not be the case and multiple phones will individually take much more time to charge, or may not charge at all.
Although the set-up is relatively simple, make sure you test your system on a sunny day to ensure everything works. Notice how long your phone takes to achieve a full charge from a depleted state.
Hopefully, you can see the benefits of owning a portable solar panel with a built-in USB charging function. I explored a solar panel’s excellent phone charging utility but it has many other applications including charging a USB lantern or flashlight. Tuck your panel in your bug-out bag and you will be much better prepared for an emergency.