I wouldn't install an electric solar system execpt in the very hottest and sunniest areas. Indeed, electric panels are so expensive that it's generally not a good idea to put them on a roof - they should be placed on a motorised bi-directional sun-tracking stand. It's not essential, but a good tracker can double energy output compared to a sloppy roof installation.
Depending on how much subsidy you get, how expensive your electricity is, and how sunny it is in your area, you may be able to break even after 5-10 years. But in many areas, such systems would never break even.
Solar water heaters are probably a much better bet - they capture energy far more efficiently, and are far cheaper and simpler. They are excellent for pool heating, but more sophisticated panels (using vacuum tubes) can produce very hot water, with industrial versions able to heat oils to over 300 F. While they are unlikely to provide central heating in Winter, they could produce 25-30% of hot water needs even in Winter, while producing more hot water than you could use in Summer. Because of their efficiency, they don't require a very sunny climate - even a very mild climate like that in the UK is more than sufficient for generating domestic hot water at low cost.
Personally, I wouldn't consider an electrical system until I already a water heating system. The water heater is also a cheaper introduction to solar power, as well as likely to pay for itself considerably more quickly. In less than 2-3 years in sunny areas.