But here's the dilemma as I see it:
• Modern technological civilization is predicated on abundant cheap (high EROEI) energy sources. Technology follows from, rather than leads to, energy availability, and hence isn't an answer.
• For reasons of both depletion (peak oil / gas / coal) and pollution (greenhouse gasses, AGW, mercury and other emissions), continued use of fossil fuels isn't viable. We've already heat peak conventional liquids (oil), and global total peak oil production is likely within 5-15 years. Gas follows shortly after, coal likely by the late 21st / mid 22nd century assuming demand doesn't collapse entirely (which would generally indicate a collapse of civilization).
• If you want to continue a technological civilization of some sort, then you've got to find alternative high-grade forms of energy. Likely a mix of electrical generation (highly fungible) and limited liquid or solid fuels production (for transport and storage needs). Capacities to produce both are fairly constrained.
• The alternative is ... a non-technological level of civilization. Likely a collapse in both technological levels and population (from famine, disease, war, the usual). Which means that the future of humanity will be relying on solar power -- collected and stored by plants. And be living in a drastically depleted environment in which many ores and mineral resources, as well as water, topsoil, and ecosystems have been hugely depleted. "Rebooting" civilization would be at best very, very difficult.
• I like a technological civilization, don't get me wrong. But I don't see it as sustainable. And there's nothing in the laws of physics, chemistry, biology, ecology, or geology which say the Universe owes us our standard of living.
Answering your question about solar PV: the economics look difficult, and numerous people who are convinced of peak oil and climate change suggest that they may well not work, see Ted Trainer, John Michael Greer, Charles A.S. Hall, and Gail Tverberg among them:
"Renewable Energy: No Solution For Consumer Society" http://www.countercurrents.org/trainer240411.htm
But that doesn't exactly leave us with good alternatives, and my feeling is that PV or other high-grade solar technologies (solar thermal, Stirling or related engines) are worth pursuing with our remaining fossil fuel reserve (we really should have been pursuing these decades ago).
What's your alternative?
Enjoy your day.