I had a short weekend in Madison, Wisconsin and discovered a few inconveniences with the current components, mostly with the solar charger and the NiMH batteries.  My batteries were mostly depleted and I was heading out at night.  Also, it is winter so the amount of daylight hours is reduced.  By the numbers, I needed 10.5 hours of daylight and for January that is all I get.  Throw in some clouds and the diminished light at sunrise and sunset and there is no way to get a full charge of 4 batteries in one day by solar alone.