With current technology, there is no pay back for solar power, and there is no such thing as base load solar power. Instead of spending billions on subsidies to incenti-vize the manufacturing and purchasing of solar panels, money should have been spent 100% on research and development into creating technology that could efficiently convert energy from the sun into electricity.
Even at $1.60 per watt material cost, given power rates in my area, daylight hours, and angle of the sun, it would take a little over ten years to produce $1.60 worth of electricity (22,857 hours at an average of 6 hours per day of peak output). There is no pay back for solar (unless you count grants and tax write offs, but the product cannot pay for itself.) These are rough numbers, but fine tuning them to bring them closer to reality would only shave a few months to a year off at best.
The other problem is capacity (maximum output.) The facility where I work has an average demand of 20MW. It is probably not even possible to construct a solar plant that could power this single facility, or provide base load power. The real estate and technology does not exist.