Unfortunately, even determining how much CO2 is "saved" by photovoltaics isn't straight-forward. In the current energy mix, their output still has to be backed up by conventional reliable generation, because our society isn't going to accept a power drop-out when clouds pass over a big solar farm, or a dust storm obscures what few panels the enviro's allow to be put up in the desert. A backup coal-fired plant has to keep its water boiling, ready to release steam as soon as it is able to pick up any slack, and that really reduces the energy being "saved".
Solar, and wind as well, are unreliable sources that are being shoe-horned into the energy game just to make their manufacturers(e.g. Solyndra, GE's Jeffrey Immelt) rich through sweetheart deals with politicians so that they can brag to their voters how they're "saving the planet", so that they can feel good about themselves. To me, that's the real emotional sloppiness.
Putting aside the CO2 as a pollutant fantasy, photovoltaic make sense in isolated environments--on boats, rustic cabins, etc. Everywhere else they operate at a loss.
Solar hot water panels actually save money and therefore make a certain amount of sense. Even so, the amortization period is quite long.
Natural gas combustion turbine generators are efficient, quick start-up systems which handle sudden or peak energy demands.