It works.. but Peltier cells are notoriously inefficient... your looking at MAYBE 8% efficiency.
Inside of an RTG with a nuclear heat source in the frozen vacuum of space the efficiency is not crippling for an extremely low power application... However with solar power you would need almost 30 square meters of lens to make a kilowatt of power.
30 square meters is "Freaking enormous"
You would also need some place to dump nearly 10 kilowatts of heat... That would require a monster of a radiator on mars.
If this was hooked to a Stirling engine you might be able to push about 30 percent after conversion which would be a better conversion ratio you could cut down the size of the lens some hopefully making it look less like a sail.
But honestly at this point any real space based endeavor would be using radio-isotopic decay as the heat source... A 10K nuclear source would only need to be maybe a foot or two compared with a 2 story monster lens that would need to be attached to a massive framework to make it move..
*average US power use per home/apartments is 1.24KW per hour. That is without needing to scrub carbon dioxide or deal with temperatures 40 degree's below zero or smelt metal. Our house uses about 4KW per hour when things are running. I would expect a martian base to use significantly more.
*The International Space Stations Solar panels produce 32.8 kW of power. I would expect this to be about the correct minimum amount of power a martian base would need if it had a smelting operation and a water hydrolysis system.
* The monster Fresnel lens though might be useful for smelting, you could partially concentrate the sun through a large window in the habitat and then use it as a heat source with another lens... Probably would use mirrors instead though.
* here is a link to the ISS truss solar panels so you can see what kinda size we would also need if we were to really use solar power. *remember it would need to be 2 to 3x larger than this even!
http://www.siggi-exner.de/ISS-sonnensegel.jpg(And here you can see the same point this picture was taken in the overall scheme of things) Look to the complete right at the little white area in the middle of the solar panels.
http://www.daviddarling.info/images/Integrated_Truss_Structure.jpgOr a high resolution shot of it a little later.
http://upload.wikimedia.org/wikipedia/commons/0/04/International_Space_Station_after_undocking_of_STS-132.jpg