I've just had a modest PV solar panel system installed on the home roof. It's an overcast, windless day here in Canberra. Today, the system has output b#gger all, but this got me thinking . . .
With my current contract, I can buy electricity from the grid at about 20 cents per kilowatt hour; I can sell it back to the grid at 45 cents per kilowatt hour. So, if I were to install a massive light system on the roof and direct its light onto the panels, I can make money 24/7. I am cutting out the middleman, namely the sun. From the profits, I might be able to financially support my modest windsurfing addiction. 
OK, so the "input to output" conversion might not be 100% efficient, but if it's better than 45%, I'll be in front. How can it go wrong? I just hope the neighbours don't complain too much about the glare.
Did I mention that it's not windy here in Canberra today? Wasn't yesterday, either. Nor the day before that, nor last week. It seems it hasn't been windy here for quite a long time. 
Nice thinking... but:
Well, if you got your panels from one of those shopping mall cowboys I am guessing the actual efficiency will be someone around 6 to 8% if you are lucky. If they installed one of those dodgy Chinese made first gen panels you might get even less.
Better rated panels, which rarely are being used under schemes here in Australia, can reach about 15% efficiency. High end panels under lab conditions might get as much as 40ish %.
Given you are getting next to nothing on an overcast day I am guessing your panels efficiency falls somewhere in the first category of panels.
If you want more details either call it into Triple J's Dr Karl or contact the guys from Mythbusters. I wouldn't be surprised if the Mythbusters guys would actually be interested in this from a theoretical point of few.
Maybe you could set up some wizz bang battery setup and suck in juice all night and pump it back into the grid during the day so that it looks like solar panels.
Though I am pretty sure it wouldnt be efficient enough to justify the expence and you are probably going to get lots of waste going from ac --> dc --> ac plus all the frequency and voltage conversion you need to do.
Could you take your panels and put them somewhere that someone else lights eg a shopping centre or Tony Abbott's backside?
Can't you just buy electricity from your next door neighbour?
Just plug his output into your input.... or is that a different thing?
Problem solved Solar pannels are just about outdated soon You will be able to pull power off your windows and roof !
This sort of idea has been tried out in Spain where they too have generous solar power feed in tarrifs.
Unfortunately the country is going broke and unemployment is over 20%.
