After 6 months of looking for options on how to remotely control the gate lock at the side of my house I have bought the Cisa Elettrika lock and am very impressed. Its a beast of a lock at 3kg and very secure. It takes 12vac to open it, although there are modules to also take dc as an input which I supply from my alarm panel, but a zwave relay would work as well.
It can be unlocked and left on catch until someone pushes it open, then locks when closed, or left with power to be open all day for instance. Only downside is that when power removed if its not then opened and closed, it doesnt lock, just stays held closed on a catch.
I got mine from the auction site where Italian (its Italian made) suppliers sell it at half the price of UK suppliers.