Powertraveller and Turbine.
After much deliberation, I decided to settle on a Powertraveller Powergorilla and Solargorilla. I also have a Texenergy Infinite Air portable wind turbine, which I use to keep the tablet going when there's no sunlight, and wind is available.
Powertraveller gear is a bit expensive but very durable.
Re: Powertraveller and Turbine.
Today was a good day for power. Lots of sun and lots of wind, so the batteries had a lot to drink.
Sorry - there was a good photo to show, but I couldn't get it to upload, so this is a pointless post : (