If we could make solar panels on mars using martian materials I see them as viable... Otherwise probably not..
This array would only produce about 700KW of power on mars:
http://www.wapa.gov/newsroom/images/FtCarsonsolar1.jpg (I put the image as a link since it was kinda HUGE!)
A french rubis class submarine's reactor produces 48,000KW's of power... and will do so for many years without refueling. It we shipped the entire submarine including the torpedoes and exocent SM39 Mines it carries to mars it would only be about the size of ONE of the panels in the picture.
(7M wide by 6M high by 73M long)
At 300,000 USD or so per lb.... which do you think they will ship to mars?
*Smelting metals and the like could easily take a couple hundred KW of power on a decent scale. IE More than a couple KG's of ore at a time. On the bright side however, the waste heat from the process could at least keep a major hab complex on mars warm.
(I believe the Alcoa aluminum plant requires 820MW/hour to run)
*Going even smaller... Toshiba has been testing 200KW reactors measuring roughly six metres by two metres. Designed to fuel smaller numbers of homes for longer, they could power a single building for up to 40 years.
They are entirely self contained, require no maintenance, and no observation. You just set them some where and you have power for 40 years. (They recommend burying it to prevent someone from stealing it.)
Will be great for places that do no have an irrational fear of nuclear power but have desperate need of electricity for humanitarian concerns such as Africa.
*And going even smaller are NASA's Stirling reactors, No one knows their final weights and dimensions but from what I have seen they are probably looking at less than 200KG in weight and fit into a space 1M/1M/1M. Course they will only produce 10-40KW... but a still will weigh a lot less than a single solar panel.
I think the power problem will be easily solved. Two things we can get on Mars is alcohol from black algae and Mars has chlorides we can extract so a alcohol/chlorine fuel cell will be the cheapest and easiest to sustain.
http://en.wikipedia.org/wiki/Fuel_cell
Just want to point out, you will need to have about the same surface area of water exposed to sunshine to produce the algae as you would need for solar panels... and you would need tens of thousands of liters of water too...
Just a quick calc... 400 Watts per meter solar iradiance... 7-10 percent efficiency of capture and conversion... maybe.. Might be lower but I will use 9% efficiency... 1 meter depth to capture most of the sunlight... So that is about 36 watts for 1000 Liters of water. To produce 40KW of power then will take... 1,111,111 Liters of water. And that is only heat power...
After converting that inside of a fuel cell at 40 Percent efficiency... you would need.... a 2,777,777 Liter pond covering 2777 Square meters.
Uhh I think that is big but I am really not sure My mind does not work well in meters. I think if you take the square root of the square meters it takes it would allow me to have dimensions... so that would be (I think I am not sure) 53 Meters by 53 meters in size for the pool... Once again I really don't know how big that is...