An article by Alex Wilson of Environmental Building News in the local newspaper Brattleboro Reformer on solar water heating with some good local links. I have done a couple houses now with solar hot water backed up with a propane or electric heating element right on the storage tank to boost water temps when needed to serve as heat (radiant) and hot water. No boiler! Marathon Water Heaters are how you do it. see also passive house institute for more information trickling to this country from Europe about how to build carbon neutral-zero energy-heatyourhousewithacat homes
Also Coldham and Hartman architects have done something similar with a number of houses in the Northeast involving upgrading the shell of the house enough to be able to heat with a single space heater such as a through the wall gas space heater in the main living area.
My own house (900 square feet, 1970, poorly insulated cape) has a modern woodstove and electric radiant heat in the ceiling which we use primarily when we are away in the winter. We heat water with a plain old electric water heater. The presence of large sugar maple trees prevents us from utilizing the sun.