I hear it's cheaper to operate, but not cheaper for the initial purchase.
I did do the math, and at the current average price, it's still cheaper to get power from the electric company. Should they drastically raise rates, and if propane prices went down lower, it wouldn't take much to swing this the other way though.
One other thing I found...regular light bulbs are a major power expense. Just switching all of these to CFL bulbs (the spirally ones) made a big difference in our electric bill. If going the solar route, I'd recommend going even further and going to LEDs (that's the next step, we're phasing these in). As they use even less power.
The only downside of LED bulbs now though, is cost. Takes a while to get the payback for the initial cost. That's why we went to CFLs first. CFLs also last longer than the normal bulbs, and LEDs last even longer than CFLs.
Now, we use a lot of lights, and for a long period of time (with 5 people on different schedules, our house has folks home all the time and at all hours), so this was a much bigger impact than some might see. Still, highly recommended to get rid of all normal bulbs. Better for your bill, better for the environment.
If using solar though, you'll want to spend the extra dough on LED lights, because it will mean more available power for other items.