How to Use a Solar Battery Charger on a Backpacking Trip

How a folding solar charger works on the trail

A folding solar panel turns sunlight into USB power. It does not store anything. The BigBlue panels in our data say this plainly: they must be used in direct sunlight while connected to your device, and they cannot hold a charge for later.

That one fact shapes the whole routine. If you plug a phone straight into a panel and a cloud rolls in, charging pauses or stops. If you plug a power bank into the panel, the bank collects whatever sun you get and holds it for the evening.

Most hikers end up with a simple chain: panel to power bank, then power bank to phone, GPS or headlamp. If you are still choosing a panel, our best solar battery charger for backpacking page puts weight, watts, ports and waterproof ratings on one spec sheet.

Step-by-step setup

Here is a routine that works for most multi-day trips. Do a practice run at home first, so you know your cables and ports work before you are miles from a trailhead.

• Unfold the panel fully and check that the cells face the sun with no wrinkles or folds shading them.
• Attach it to the outside of your pack with the carabiners or loops while you hike, or lay it on a rock or tent roof at camp.
• Plug your power bank into the panel with a short cable. Some panels include one, such as the 50cm USB-C cable that comes with the BigBlue 28W.
• Look for a charging indicator. The BigBlue 28W has an LED that glows solid blue when it is charging properly.
• Re-aim the panel every hour or so at camp so it faces the sun as it moves across the sky.
• At night, charge your phone and other gear from the power bank, not from the panel.

Charging an iPhone

Newer iPhones charge over USB-C and older ones use Lightning, so check which cable you need before you go. Pack your own cable that matches your phone. The BigBlue 28W listing notes that a cable for Apple devices is not included.

Port choice also matters. The BigBlue 35W lists two USB-C ports and one USB-A port, but its Type-C1 port, the 25W one, does not support Apple devices. The GEYOTO 45W listing says its 25W USB-C port works with iPhone and iPad, and it has three ports in total.

For the best results, charge the power bank from the panel during the day and let the bank charge the iPhone. This keeps the phone out of direct sun, which matters because phones that get hot slow down or stop charging.

Which panel suits which trip

Weight and folded size matter on the trail, but so do ports and waterproofing. The figures below come from the product data on our comparison page.

If your hikes involve a lot of shade, such as forest trails, look at panels with parallel circuits. The BigBlue 35W uses a dual parallel design so one section can keep charging while the other is shaded.

Common mistakes that waste sunlight

Most poor results come from placement, not from the panel itself. These habits make the biggest difference.

• Charging through glass. The BigBlue 28W manual advice is not to use it inside a window or windscreen.
• Letting a shadow cross part of the panel, such as a pack strap, trekking pole or tree branch.
• Laying the panel flat when the sun is low. Tilt it so it faces the sun more directly.
• Plugging a phone straight into the panel on a changeable day instead of using a power bank.
• Hanging the panel on your pack but keeping it half covered by a rain cover or a stuffed side pocket.
• Expecting the rated wattage. Actual output varies with sun angle, temperature and the device you connect.

Safety and care

Solar panels are low voltage, but a few precautions protect you and your gear. Keep the USB junction box and ports dry. The BigBlue listings warn that the junction box is not waterproof, even when the panel surface has a higher rating. The GEYOTO 45W listing also advises keeping the charging ports dry and wiping the panel before you store it.

Do not leave phones or power banks in hot, direct sun, and never charge a battery that feels swollen or very hot. Stop using a cable that is frayed or damaged.

In a thunderstorm, take the panel off your pack and stow it. Metal cords and carabiners on a pack are not a place you want to be attached to when lightning is near. If you scramble on rocks or exposed ledges, secure the panel so it cannot swing or snag, and do not stop to adjust it in a risky spot.

When solar is worth the trouble

For a weekend trip, a charged power bank alone may be enough. Solar earns its weight on longer routes, in places with reliable sun, or when you rely on a phone for maps and photos every day.

If you also work on vehicles or batteries at home, our guides to the best battery charger for AGM batteries and the best battery charger and jump starter combo cover that side of things. Those are separate tools from a trail panel, so match the product to the job.

Frequently asked questions

Can I charge a power bank and a phone from the panel at the same time?

Yes, if the panel has several ports, but the sun output is shared between them. Each device charges more slowly. It is usually better to fill the power bank first.

Does a solar charger work on cloudy days?

It works, but much more slowly, because it needs direct sun for best output. Panels with higher cell efficiency or parallel circuits cope better with weak light and partial shade.

Should I charge while I walk?

You can. Clip the panel on top of your pack with the cells facing the sun and connect a power bank. Keep the cable and bank secure, and expect less output than when the panel is aimed at the sun at camp.

How do I store the panel after a trip?

Wipe it clean and dry, fold it along its creases, and store it with its cables somewhere cool and dry. Check the ports for moisture before packing it away.