Would solar panels now be beneficial for my house?

Last week I asked " Would a heat pump be a good idea for my home?" and received many thoughtful comments.  This week I would like your opinions on solar panels. I understand they are becoming more efficient, but they are being so aggressively marketed that I doubt all the sales literature.
  • Would solar panels be more beneficial for my house than they were a few years ago?
  • How much has their efficiency changed?  Is it projected to increase further?
  • How much has the cost per kilowatt-hour gone up - or down?
  • How much has the cost of electricity, supplied by my power company, changed?
  • Should I consider the costs and benefits of an inverter? 

As you can tell, I'm rather interested in clean energy sources. Two years ago I bought an electric car and am loving it for a multitude of reasons: clean energy, saving money on gas, and being an example to my twin daughters about what we can do help the Earth.