Coupla things:
- Your solar tank is simply not big enough to make any difference for space heat;
- Solar heat and heat pump inhabit the same warming zone. They each can get you up to 80% if you want that economic balance, but you need some kind of boost for the rest, which in your case is oil. If yer willing to pay for the tubes sure, you can get 100%.

96 is pretty respectable for flat-panels if you're in a northern clime, but you're going to want evac-tube for further expansion to get that temp up higher. AMK, Apricus.

I would not wait on PV, particularly if your state offers credits or if your power is not socialized. I've listed the panels before, but Sanyo packs the most punch at 16.2W/sqft.