One of the big problems on an expedition is keeping the electronic stuff charged. Even on a relatively short expedition such as mine, with the number of electronic items most people carry, charging is critical and just carrying enough batteries for the trip can result in too much weight, volume or expense.
I have a Brunton 26W folding solar panel that does an admirable job of harnessing the sun's energy and outputting power.
However, charging my Nikon D7000 battery has always been a problem as nobody seemed to produce a 12V car type charger for the EN-EL15 batteries that it (and several other cameras, including the flagship Nikon D800) uses. I had previously tried a cheapo eBay charger supposedly good for charging the batteries but I found that once charged the battery showed as being almost a throw away item. The Nikon has a system that not only shows charge level of the battery but also nominal age on a scale of 1 to 4, 1 being new and 4 being just plain worn out. After charging with the cheapo the battery would read as a 4, recharging on the genuine Nikon charger restored it to a 1 but it created doubts about how much damage was being done to the battery.
Recently, I came across a company called Hahnel. Based in Ireland, they produce a range of chargers that will charge the Nikon battery. I ordered one of their chargers called a Unipal II and received it a couple of days ago.
After charging both of my Nikon D7000's batteries and some other different sorts of batteries I can genuinely say I am impressed. The batteries all charged without problem.
The Unipal II can charge AA's, AAA's, almost all lithium ion batteries, as well as having a USB outlet allowing it to charge iPhones etc. A truly versatile charger.
And even though it has the ubiquitous "Made in China" on it, quality looks to be pretty reasonable.