ᐅ Upgrading a solar thermal system

Hello,

For my planned new build, I initially intended to install solar thermal systems only for heating domestic hot water. Is it possible to add more solar thermal panels after a few years to also support space heating of the building?
The system used is the VITOSOL 100-FM from Viessmann.

Nice, but then you also need a new (larger) storage tank or an additional one. Plus the extra piping and safety devices. Where else would you put the hot water in summer?

So, I wouldn’t do it; it’s pointless... you won’t save anything anyway because you have to work on it twice.