Personal Solar for Devices in the Backcountry

I don't go into the backcountry device-free. A smartphone, with backcountry GPS software, and a digital camera are always with me. Planning for an 11-day rafting/hiking trip through the Grand Canyon in April raised the issue of how to power my gear. I decided to go solar to minimize battery consumption. A February week in the Mojave desert (right) gave me a chance to sort out candidate devices and to configure a compact but workable system. Here are reports from the Mojave and Grand Canyon trips.

Mojave Desert

I build my system around USB connectivity. My phone and camera both charge via USB and my Anker 21W solar panel charger outputs via USB.

Direct charging of the smartphone did not seem practical -- it's charger would constantly hunt for a connection in low-light situations, which cannot be good for the charging circuitry. (This solar panel does not have an indication of how much charge is being delivered, just a single charge/no-charge LED.)

I solved that problem by having the solar panel charge a USB portable charger, which tolerates a low-light trickle charge, then use the portable charger to charge a device.

Two small USB portable chargers of ~3000mAh each were in my final configuration, so that I can have one on the trail while the other is re-charging at basecamp.

I rejected a USB AA/AAA battery charger after testing. It did not seem to charge batteries well when connect to a conventional power supply, so I did not bother with a solar panel test. Instead, I added a USB-charged LED headlamp to my collection of devices to reduce battery use.

I'll still travel with backup batteries for my camera and a backup AAA-powered headlamp, but my goal is to see how much I can rely on solar. Reduced battery consumption and more use of renewable energy are two Green ICT goals.

Grand Canyon Update

The gear worked well on the trip. The biggest challenges came from the 'use case', not from the gear itself.

The duration of direct sunlight is very short down in the tall, narrow canyon. We broke camp each morning before direct sunlight in order to get back on the river and we arrived at the next camp late afternoon after direct sunlight. It also was not practical to have the solar panel out while underway because the raft was crowded with people and supplies. Lunch and hiking stops, when logistics permitted, were the only opportunities to unfurl the solar panel.

Despite this, I was able to generate enough power to charge my iPhone and my Olympus TG-3 waterproof camera, as well as help others keep their devices powered.

Both the phone and the camera have in-unit charging, which avoids having to carry a charger or swap batteries. Not opening devices to swap batteries was particularly important with all the fine sand blowing around the canyon.

I used a microfiber cloth to keep the solar panel clean. I would periodically dust it with a dry cloth and only used a moist cloth after dusting if really necessary.

The powerful and turbulent Colorado River will grab anything it can and heavy wind gusts help feed the river's appetite. For these reasons, it was important to keep the solar panel secure while charging even though the raft was beached during this time. The panel comes with 4 grommets, but I had to supply my own carabiners to secure the panel to the raft's lines. The design allows for only two carabiners to remain attached when the unit is folded. The other two would rub on the solar cells.

The built-in pouch that protects the two USB ports only has a small velcro tab, so it is useless for storing accessories like cables or a battery. I used the custom-sized plastic bag in which the unit shipped to help keep the unit dry when it was stowed in my pack while running the rapids, but that seal was minimal and became fatigued from frequent use. I now have a dry bag for transporting the unit and its accessories.