Yes solar water heating is a great way to save energy.
Here in the Costa Blanca area of Spain you can expect to get 80 to 90% of your yearly domestic hot water for free by using a vacuum tube solar water heater.
But it is a real shame it is still not used much here.
The other day I was at Alicante castle, I looked down across the roof tops of the city, I only saw 2 solar water heaters.
The sun was really strong and I thought it seemed such a waste that all that free energy was not being put to use !
Tony cssolar Spainwww.cssolar.weebly.com