I am building a passive solar home with Durisol Block and the best windows I can get. It is a 1 story with a walkout basement which is living space as well (about 2500 sq feet in all). It is facing due south with > 10% windows on that side. We are putting radiant floor in the basement (concrete floor) and main floor ( hardwood). I need to know if I can use an electric hybrid hot water heater (Water heater with heat pump) to heat the home AND provide domestic hot water. I am in Ontario Canada, latitude 45 degrees north and we get snow 5 months of the year. Any configuration which might get us there would be welcome. Price is a consideration. I feel the sun will heat the home most of the time and we will have a wood stove on the main floor as backup. I don't use the standard calculations to determine the energy requirements to heat the home effectively as the solar displaces / skews much of the numbers with regard to that. Anyway, I probably am missing a whole bunch of information for you to help with but I am open to suggestions if you have any. Electricity is the power energy source I have chosen as I have the capacity to generate my own ( in the future). I just can't justify an electric boiler right now if I don't need it.
     Also, I understand that OSB is available somewhere with an aluminum plating which would make the radiant floor on the main level very efficient. This too is a consideration in purchasing an energy source. How expensive is it? Does it work. Is it worth the price? Enough said.

Since hybrid hot water heaters work by pulling heat out of the room air, they're kinda useless as a space heating heat source. If your goal is to just warm the floor a bit while lowering the air temp of the room a bit it's still a loser, since the amount of heat those suckers will move per hour just isn't that much- you won't be cruising on cozy 24-25C floors with 18C room air using one of those.

To get even close to satisfactory performance out of radiant, using heat-loss calculation tools figure out what the heat load (in kilowatts) is on the zones you hope to heat with radiant when it's 0C or -5C out. that's the smallest sized heating element you need in your electric hot water heater that makes even remote sense. It takes an EXTREMELY well insulated house to use even higher power electric tank heaters as a primary heat source in Ontario. You might be able to get there using a larger electric on-demand water heater as a boiler, but the difference between a decent on-demand heater vs. an electric boiler isn't all that much.

Foil faced OSB is useless as a heat spreader- you need a real cross-section to the metalization to get much benefit (1mm minimum metal thickness 3-4mm better.) Foil faced OSB makes some sense as exterior wall sheathing in cooling dominated climates since putting the foil to the exterior allows it to reject at least some of the heat coming in from the hot siding material, or foil-side down in roofing apps to keep from radiating heat into the attic,( see: http://www.gp.com/build/product.aspx?pid=5857 ) but makes no sense at all in a heating dominated climate. There's no real cheaping out to be done- aluminum costs what aluminum costs- you might as well use plates designed for the application, (or layer the sub-floor with sheet aluminum of a significant thickness, which would be as effective, but probably more expensive) and build your sub floor up out of standard commonly available goods.

Sounds like you should consider a smallish geothermal system. Solar and wood could supply the rest.

I suspect that for the cost of a "smallish geothermal system" the house could be super-insulated to PassiveHouse standards, at which point an electric hot water heater COULD heat the place with kilowatts to spare...