No, it is not profitable in most cases. Read the previous comments in this thread and check out the other similar topics in the mining section. I wish it was profitable though and I hope the time will come when they will be able to make cheaper solar systems and thus sell them for lower prices then now. I really support the usage of the Solar energy, it's just pity it is too expensive.
That is certainly true. Since Solar panels, are too expensive, it could limit yourself from ever being able to mine Bitcoin with it, as you would need good capital, in order to get started with this operation. However, if you visualize this for the long term, then you might make back what you have initially invested into solar panels, as time goes by, thus making it an ideal investment.
I've always been fascinated by using alternative energy, in order to mine Bitcoin, in eco-friendly way. This would definitely increase your chances of profiting, than using normal energy. However, I've heard rumors that countries like China and Venezuela are ideal to get started with any mining operation, due to low energy costs, among many other factors.