The flashing lights are powered by a 12V transformer that plugs into a powerpoint in the house where the sign is located. The total electricity cost to run the lights is less than 70 cents per year:

The lights are LED based. They draw 0.65A of current at 12V = 8W. Only one light is on at a time.

The lights strobe on for 50% of the time and off for 50% of the time when operating. Total on time is 1.5 hours per day.

There are 12 weeks of school and public holidays per year leaving 40 weeks of school = 200 school days per year.

8W x 1.5 hours per day x 200 days per year = 2400 Watt Hours = 2.4 KWH per year.

Electricity costs a maximum of 22 cents per KWH for peak usage.

2.4 x 22 cents = 53 cents per year.

The lights are driven by a computer controller that is always on.

The controller draws 6mA of current at 12V = 0.072W.

0.072W x 24 hours x 365 days = 630 Watt Hours = 0.63 KWH per year.

0.63 x 22 cents = 14 cents per year.

There is a GPS satellite receiver in the controller that obtains the time and date from the satellites every hour.

The GPS satellite receiver draws 80mA of current at 12V = 1W.

The GPS is turned on for 10 seconds per hour = 240 seconds per day = 0.066 hours per day.

1W x 0.066 x 365 days = 25 Watt Hours = 0.025 KWH per year.

0.025 x 22 cents = 1 cent per year.