Here is a report from a northern California homeowner who installed a large array of solar panels on his home six months ago, and has been carefully tracking energy usage since then. Not surprisingly, the panels generated a lot of power during the summer months, and output has been much more variable as the angle of the sun has changed during the winter (meaning less power). More cloudy days in the winter also affects output. But a year ago, this guy had a $446 electric bill for the month of January, and has paid only $390 for the entire second half of the year. This does not factor in the initial cost of the solar panels, but hints at the substantial cost savings available--solar energy is free.
Keep in mind however, that solar, like wind, is not a complete energy solution. Solar panels generate no electricity at night, and wind turbines don't generate any electricity when the wind does not blow. Coal and nuclear power have to generate a substantial portion of the base load power in the U.S. to keep the economy working.