Twilight Sensor

It's pretty much essential that your home knows if it is dark or light outside, if you want to control things like security lighting and automated curtains at the right times. Typically, you can buy twilight sensors to operate individual lights and devices but doing this in a centralised fashion provides more intelligent control.

The weather is an obvious factor in when it gets dark at night and lighter in the morning. For the purposes of control and automation, it makes sense to take account of the outside conditions. To ensure these don't result in hysteresis the control system must allow for changing weather and calculating the local times for sunrise and sunset can help validate the sensor outputs.

Also worth a mention is that when it gets dark, you would not want to close all the curtains at the same time! This does not make your house look occupied and creates a large load spike.

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