The ones that have a watt of standby are the really old models (probably not sold for the last 30yrs) where you'd have an LDR controlled relay with no electronics

Anything more modern than that, even if it has a similar case, will use less power

A low-voltage photocell uses like 5mA @ 24VAC these days, it’s nowhere near a watt. You can buy a wireless battery powered photocell or occupancy sensor that will last a decade.

This Acuity occ sensor/photocell combo draws 4mA @ 24VDC: https://pdmassets.azureedge.net/library/SS/documents/specshe...