...okay ? But how the bricks help ?

Like, there is some merit in say heating up the "heat battery" at peak solar power (or just when grid energy is cheapest) then using that to heat directly but... you're still doing it at 100% efficiency while heat pump does that at 200-300% using nothing but ambient temperature to get that efficiency.

I guess you could use it as a hybrid solution with heat pump for very cold climates that would normally disqualify heat pumps (heat the brick during the day, use heat pump to get the heat back) but even that is kinda meh.