The idea is simple.
What if you used a hardened surface of a Peltier Element and slided that along some solar heated surface? Then I think you get a much more warmer hot side. At the same time you cool the upper side with a fan. This should generate more electricity than just placing the peltier still on surface.
So the idea is to sum up small patches of heat. With movement and low friction contact the added energy for motion is ?small. Like for a sliding bearing. At least solar energy could move the heat collector also.