How much solar could be got from the Indian desert?
Well, the 'Great Indian Desert' is 200,000km2. [ http://en.wikipedia.org/wiki/Thar_Desert ]
Let's conservatively assume 10W/m2 (10MW/km2) http://www.withouthotair.com That makes 2000GW or 1kW for 2billion people. So India can power it's existing energy consumption from the Thar desert, even with 2billion people ; but it can't power an american (10kW/person) level of consumption from this source.