The searchlight towers in Vancouver at Tower beach and Wreck beach
were to detect Japanese surface vessels. That is why they are at the waters edge.
The Germans used radar like Freya and Wurzburg to do the same. Freya was able to detect RN destroyers at a range of 60 miles, far more distant than a searchlight. The searchlights used by the Germans were mainly for air defense and were located inland from the coast of France but closer to the coast in Belgium. It seems the flight paths of Bomber Command were over Belgium. In 1942 Hitler ordered most of the searchlights back to the German border as Allied bombing was having an effect.
There was a major effort just before D-Day to take out the coastal radar sites.
An excellent book covering this topic is "Most Secret War" by R.V. Jones. He was the British scientist involved in overcoming the German defenses.