re: I've been thinking about that....
Get some pros in to do a complete analysis of your costs and benefits.
Note that hot water heating systems are easier to add rooftop solar heating units to. No way in your climate that will cover all your heating, but every BTU that comes in will be a free one.
Lowering the overall thermostat and using some good local electric heaters where you spend most of your time doesn't hurt either. Those sealed oil jobs that look like little radiators work pretty good in small rooms and are safer than normal electric ones.