1 square meter evacuated solar tubing is used for hot water systems not home heating. It's a question of output temperature, the warmer the water the less cost efficient and more costly the system. High end systems include a backup water heater which means you directly save 1k on a hot water heater.
Anyway, for home heating you don't need 'hot' water, a heat pump operating on even 60f water vs 0f or below air is very efficient. You can also pre heat cold water with a flat plate feed that into your normal water heater and again save a lot of energy.
PS: Also, many people pay 1,000-2000$ / year on home heating even with a well insulated house. These systems generally have payback period under 10 years, assuming you actually need significant amounts of heat.
In the US we mostly use them for pool heating, as anything else costs to much, but somehow they are ignored for other uses.