These are some of the best matches for solar, because they give you a big, flexible electrical load to soak up your own generation and cheap-rate power — which is exactly where solar's value is highest. All-electric homes with a heat pump tend to get strong results: they self-consume a lot of their generation, and pairing a well-sized array with a battery can cover a meaningful share of the heat pump's running cost across the year. Some even nudge their BER up a notch after installing solar.
An EV is arguably an even better fit, because you can shift its charging to whenever power is cheapest or most abundant. Charge on a cheap night/EV rate (often around the 2–5am window at a low rate), and use solar surplus to top up during the day. That flexibility is what makes a battery and a smart tariff pay — the EV becomes a giant, schedulable load that absorbs cheap and self-generated electricity instead of expensive peak-rate units. An EV plus solar plus a night rate consistently delivers the best overall economics.
The honest caveats: a heat pump pushes up your winter electricity demand precisely when solar generates least, so solar won't power it through the dark months — it offsets cost across the year, with insulation and a smart tariff doing the heavy lifting in winter. And the gains depend on actually shifting load to match cheap/sunny periods. But if you have (or are getting) a heat pump or EV, you have the load profile that makes solar — and especially solar-plus-battery on a smart tariff — most worthwhile. Size the system with that future load in mind rather than just today's usage.