Filmmaker George Thengummoottil built an affordable, custom solar charger with only three parts.
Kerala, India-based filmmaker George Thengummoottil wanted to spend two weeks capturing one of the most remote treks in the Himalayas, where there would be no access to power for recharging his camera gear. To meet this challenge, he tested many of the existing systems like solar backpacks and power banks, but he found them lacking, since the combination of the thin mountain air and low temperatures made large battery systems ineffective, and most solar backpacks required too much time to do their jobs. However, he still needed power for his GoPro Hero4 and Canon T1i through his journey.
To overcome that obstacle, Thengummoottil discovered a cost effective solution that worked despite the challenges of working in the highest mountains on earth. Rather than spending hundreds of dollars on a custom designed solar backpack, he instead went to a hobby shop and purchased a 12 volt 1 amp solar panel, of the type that are widely available from eBay in the United States for around $20. Solar panels are an especially good option for extreme temperatures like in the mountains, Thengummoottil pointed out, because they function even at temperatures below freezing.
Thengummoottil then custom wired the solar panel to the socket for a car cigarette lighter, using parts that any electronics or auto parts store keep in stock. Since most car battery systems are either 12V or 24V, he was able to use car chargers plugged into the cigarette outlet to keep his Canon and GoPro cameras charged throughout the project. (He noted that the 12 V solar panels may give a peak voltage of 24, but this is perfectly fine.) He provided us with the diagrams below to show exactly how the wiring was rigged:
Even on snowy or icy days in the mountains, provided the sun was shining, he was able to keep working through his 14-day shoot with charged batteries. His 250Ma panel would take about 4 hours to charge a 1000MaH (milli amp hour) battery. If your particular camera didn't come with a car charger adapter, it most likely came with a USB charger, and car-to-USB adapters are available widely for less than $10, so this should be a cost effective solution for many filmmakers who are planning productions involving long periods of time off the grid.
For this system to work, you need to be constantly charging one battery while working off another, and you need to be shooting in such a fashion that you don't run through one battery before the next is ready to go. With smart battery conservation choices, keeping the camera powered down when not in use, and turning off unnecessary features, great results are possible.
You can see his final result, Singalila, here.