It will do that
A) when the sun is shining and at a high enough angle (about 10% of the time) and
B) they aren't running anything more than a toaster inside.
The rest of the time they are buying power just like the rest of us. I guarantee they are not storing energy. It is also likely that they are getting a subsidy for that "left over" power because the power company is forced to buy it at the regular rates (i.e. meter spins backwards) even though that power is not produced at peak time when it is needed and therefore should be priced less.
Just be thankful you don't live in Germany. There your neighbors put up solar panels and you are forced to buy their power for 50 cents per kWh (what they get paid) plus electric company markup. That compares to the five cents or so we pay here for wholesale power from a real provider. It is the ultimate scam, rich people getting paid by poor people for an imaginary product so they can all feel good.
Well I suppose this is the whole point of cap and trade isn't it...to destroy our middle class and get the ruling class richer....sort of like the Soviet Union or Zimbabwe.
Fundamental Change! Treasonous Bastards.
BTW, our day care center is really nice....just like the rest of the campus - has to be one of the best in the world. Here's something about one of our stores: http://www.nikebiz.com/responsibility/considered_design/features/nike_innovates_at_retail.html