Care to put some magnitude numbers on that "thermal pollution" effect? How does it compare to, say, the emission of warm water from conventional power plants into the marine environment? Or urban heat islands? How is the albedo of the plant versus that of the existing terrain?
I'm also confused about the idea of a desert "becoming" uninhabitable. The whole discussion reminds me of people talking about bird death effects only related to wind power, ignoring all other environmental and man-made causes. I do accept that the desert is an ecosystem of its own and the usual checks should be made that you're not eradicating the sole habitat of an endangered species.
Edit: there's even an environmental impact check in that EISA PDF from my other comment.
The Ouarzazate solar complex study area is not part of any protected natural zone; however, the following are located on its outlying zones:
The Mansour Ed Dahbi artificial lake, part of RAMSAR (site of the dam – located 6 km South of the site);
The Bouljir dorcas gazelle reserve (13 km to the North-West of the site);
The Iguernane Reserve (15 km to the North–West of the site);
The key site of Sbaa Chaab (20 km East of the site);
The Biosphere Reserve (solar complex in buffer zone B of the Biosphere Reserve).
None of the plant species found in the project site and its environs is considered rare or endangered.
The solar complex project site is considered to be of low heritage value.
The areas with high heritage value are located on the eastern and western reaches of the project site.
The emission of warm water from (conventional and nuclear) power plants is a significant issue but it's kind of not the most prominent issue w.r.t. nuclear power so it tends to be ignored (e.g. the fact that the water is slightly more radioactive or contaminated gets a lot more attention -- it's well known that heat-loving ecosystems develop around power plant outflows).
The magnitude of the thermal pollution varies by technology. Morroco is planning a heat-concentrating system (boiling water with a giant parabolic mirror, in essence) which produces very intense heat in the middle and actually cools the land in the surrounding errors (since the mirrors will have a much higher albedo than rocks and sand). I'm not actually sure if this is going to be a net increase in heat absorption, so this might be a non-issue. (This form of solar generation is apparently more expensive than photovoltaics, though.)
The Union of Concerned Scientists is much more worried about water use, especially in arid areas, with such power plants.
Photovoltaics (solar cells) are pretty much black and about 20-30% efficient) so they're absorbing more incident radiation than rocks and sand and then converting 70-80% of it to heat. We see similar effects from urbanization of desert areas (e.g. Phoenix and Las Vegas) so it's not like the effects will be unprecedented -- they just shouldn't be ignored.
That's exactly the misconception folks have about desert right there, in that quoted "becoming". The idea is that deserts are worthless, containing no life. Probably because they contain nothing that humans value for their own comfort.
Yet deserts have lots of life, unique life, that because of the harsh environment is exquisitely tuned to the desert environment. This is the stuff that will be lost if the sunlight is gone, the heat goes away, the moisture balance is upset by so much shade. Plentiful shade and cool and wet are good for people; disaster for the desert ecosystem.
The 'thermal pollution' is, curiously, cooling instead of heating in this case. Light is turned to electricity instead of falling on the ground and becoming heat.
I'm also confused about the idea of a desert "becoming" uninhabitable. The whole discussion reminds me of people talking about bird death effects only related to wind power, ignoring all other environmental and man-made causes. I do accept that the desert is an ecosystem of its own and the usual checks should be made that you're not eradicating the sole habitat of an endangered species.
Edit: there's even an environmental impact check in that EISA PDF from my other comment.