Solar energy is wonderful, but the point I was trying to raise is that for people to sell their excess power onto the grid at the same price they pay for it requires that someone else pay them at that rate PLUS the costs of maintaining the grid, as well as administration costs, etc.
So, ultimately I think it's going to come down to a question of competing labor costs. 1) How much do solar producers expect per kwh and 2) how much are fossil fuel producers willing to take per kwh generated? Solar may end up costing more than fossil fuel only because the people supplying it are indexing their price against what they pay for electricity, whereas the fossil fuel prices are based on supply and demand.
Eventually, if enough people invest in solar panels to make feed-in competitive, there will be supply-side competition and the cost paid to solar-cell owners will go down. However, the question is whether this low price will be sufficient to motivate private individuals to buy and maintain solar systems. It may turn out that big companies undercut private individuals eliminating home-based solar collectors.
At that point, my question would be what was gained economically by switching to solar, if it just becomes another profit industry the same as fossil fuels. Granted the ecological benefits are great, but it's not like people are going to be any more free economically than they are now, even though sunlight is 100% free. See the problem?