Solar Power

I am considering the installation of solar power, and have started to investigat the variuos options. Nice and shiny websites are all well and good, but i thought i would ask for some real world experience of them...
I know there are two main types - hot water systems and electrical (photo voltaic) systems.
I currently have a oil fired central heating boiler which serves white a large property. Is there any way i could use solar power to serve this same central heating system,supplementing it with the oil when required?
Also, as far as the PV systems are concerned, does such a system have a storage capability, or it is a case of use it or lose it (or export it)?
Lastly, in terms of the cost benefits of either system, i am concerned that if there really was money to be saved in installing such systems, everyman and their dog would have them. Does anyone have any information about the relative cost savings associated with hot water or PV solar installations?
TIA for any observations or comments.

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