But I suspect heating is more expensive than cooling.
In Romania (45-46 degrees latitude) I can tolerate up to 25°C, and an uncooled room (that is not directly below the roof) only ever gets to 28°C, so it'd need 3Δ°C.
Whereas in winter, an unheated room can get to 14°C or lower, but the lowest temperature that doesn't affect me working from home is 23°C, so it would need upwards of 9Δ°C of heating.
Therefore, a heat pump for heating needs more power than an AC for cooling, which is why it would be more expensive.
But "heat pumps" (which is exactly like AC, but in the UK 3x more expensive because its "renewable") need to run for heating.
So I agree with you, solar and AC are perfect for cooling, heating might need other sources of electricity.