I agree with Roy above. To heat with
solar electricity you'd need like 10 or 20 times the area covered in solar photovoltaic panels, than if you were to use the heat of the sun's light directly, instead.
Even simpler than a solar water heater system to heat a house, would be to design the house to be a passive solar house. That means, design it so that most of the windows and most of the rooms that you need to have warmed are facing exactly south; have plenty of thermal mass inside the solar heated spaces, good insulation, good thick curtains for winter nights, ... and if your location is adequately sunny, that's often
enough. Or it leaves you with a very small need for active backup heat.
I've lived in a cold-winter climate with only passive solar heat for about 20 years. I like it. (Though maybe I'd use backup heat on January nights if it were possible). Most homes and offices in this area use heating of some kind from October to April or May.
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