There are better people than me to advise on electric specifics but from my experience you don’t need a Harvi. Just a hub and a Zappi.
even if you add solar at some point you may well not need a Harvi. I haven’t got one.
a 60amp mains fuse should be OK. I had one up until last year. If the incoming mains cables are sufficient, Your DNO may be happy to upgrade it. Mine is now 100amps.
the hub allows access to Zappi controls and shows what power is going where
here’s mine right now
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