I'm all in favour of converting to solar, even if only partly as you can move things across over time.
I've been living entirely off the grid for over 10 years now with reliable power and not a single bill.
Of course I paid a lot up front and still have to use a generator on occasion.
By coincidence I just read this article on this link posted on another threadhttp://blog.makezine.com/archive/2011/10/how-open-source-hardware-is-kick-starting-kickstarter.html
To save you reading the entire thing, in an interview the fellow says
I knew this because I was living in my cabin at the time, and the only supply of electricity I had was my meager 145-watt solar array.
So it can be done with a single panel although you can't do refrigeration, heating or cooking with electricity, you need gas for that. Certainly I've lived on 240W of panels (including a fridge and computer but not heating or cooking) although I have a much larger system now.
In a nutshell I'd say if you just want to power the bedroom light it's a waste of money, but if you eventually plan to be independent of the power supply companies then I'd make a start. Where I live power has at least doubled in the last 10 years and looks like increases will get more frequent and larger in future, not that I pay much attention to such matters