A Digital India Initiative

Salem: Smart street lighting for energy saving

October 7, 2019

Salem City Municipal Corporation (SCMC) had 27,632 street lights in the year 2014. The lights were mostly the high-pressure sodium lamps and metal halide bulbs and leading to a high energy consumption of 11,882.64 Mwh units, with an electricity bill worth Rs.7.55 crores. Sodium vapour lights are highly energy inefficient, prone to failures, have a very short life and emit CO2. Very often, it was seen that street lights stayed ON well past sunrise and there was a need for a solution to prevent wastage of electricity.


SCMC sought to replace the existing conventional street lighting system with LED technology-based lights with smart controls. The project was expected to bring about substantial savings through reduced energy consumption and reduced replacement costs.

The energy savings project (ESCO) was taken up for implementation in SCMC in 2014.

  • Out of 27,632 street lights, 40w17,470 tube lights were converted into 20w LED lights.
  • The corporation also converted 643 sodium vapour 70w lamps, 603 sodium vapour 150w lamps, high-mast 400w metal halide lamps and 300w induction lamps into 30w, 60w, 200w LED.

Under the Smart City Project 8,461 smart lights were installed at various locations, replacing the age-old sodium vapour lamps. These smart lights are equipped with an external controller which can be switched On/Off/Dim as per the command given, and can log all the critical parameters of the street light fixture connected to it.

Currently, the SCMC has a total of 29,839 LED street lights.

Features and Benefits

  • Each street light switch box is equipped with a controller, which allows automatic switching on and off based on the available annual sunrise and annual sunset timings.
  • All controllers are GPRS/GSM-based remote streetlight monitoring systems with capacity for self-protection from short- circuit, over voltage and anti-theft alert.
  • Smart lighting can automatically dim and schedule the lights. For e.g. 100% output from 7 to 11 pm, 80% power output from 11 pm to 1 am, 50% power output from 1 am to 4 am and again 100% output from 4 am to 6 am.
  • User configurable ON/OFF/DIM schedules are programmed on a daily/monthly/special events basis.
  • System has the capability to capture and provide all electrical parameters at variable time intervals and live data collection.
  • Monitoring Meter Power Consumption, Burn Hours, Power Factor, Current and several other parameters at an individual light point level, allows to manage the city lighting dynamically, interactively and flexibly.
  • Alarm Dashboard provides alerts and auto notifications by identifying and understanding each lamp failure immediately along with reason for failure.
  • The maintenance team knows upfront which parts they need to carry.

Smart Monitoring through Central Control and Monitoring Center (CCMC):

  • All street lights are now connected and monitored at CCMC.
  • In the first 30 minutes, each field engineer gets an alert and status on his mobile phone to check specific points for breakdown or repair.
  • CCMC gets an alert for breakdown and the repair requirements.
  • The system provides various reports including device status (On/Off/Dim/Communication faults) location-wise, zone-wise and ward-wise.
  • In case of a situation, data also provides status of on/off lights in daytime for specific hours.
  • The additional aspect of data is that it also provides information of energy consumption,for e.g. if a light takes more than specified voltage power consumption then it reflects through report and corrective actions took place based on power factor.
  • Each smart light works on Astro-timing and is based on drivers and sensors setup to smart lights it leads to automatic on and off depending upon sunshine and sunset time.

Based on reports generated, the data analyst reports the status to the concerned officials and decision-making can take place with corrective actions.


Outcomes and Impacts

  • With implementation of the 29,839 LEDs, the city has saved 77,92,142.29 kwhunitsof energy consumption and the cost of saving is Rs.4.95 Cr.
  • LEDs provide better quality lighting, lower energy consumption, and reduced CO2 emissions.
  • Brighter roads increase public safety and the new smart look is enhanced by decorative brackets.
  • Lux Levels have increased by 25% and that too with significant decrease in power consumption.
  • Adjusting light brightness level in areas where more accidents or criminal activities is possible.
  • LEDs have a long lifespan, thus reducing the issue of burned out street lights especially during night time.
  • Recent studies have shown that due to the installation of bright, white LED street lighting, crime rates have lowered. With less dark, illuminated pockets, people feel safer walking home late at night in comparison to when walking under traditional street lighting.
  • Use of LEDs is leading to reduced pollution in the surrounding area.

Therefore, the utility of these new lights can be realized everywhere, and the process of putting them into place is also straightforward. The feasibility of implementation is also unproblematic, for the incurred costs are offset by long-term operational savings. In the next phases, it is going to be replicated and readapted to regions across the city.