Solar street lights

Solar lighting involves using solar energy to power lighting systems. Solar panels convert sunlight into electricity, which is stored in batteries and used to power LED lights. These systems are eco-friendly, reducing reliance on fossil fuels and lowering electricity bills. Solar street lighting systems harness photovoltaic technology to convert solar energy into electrical power, providing sustainable illumination for outdoor spaces. These systems are particularly advantageous in regions with limited or unreliable grid access, offering an eco-friendly alternative to conventional street lighting.

Components of Solar Street Lighting Systems:

1. Solar Panels: These are photovoltaic (PV) panels that capture sunlight and convert it into electrical energy by using semiconductor materials like silicon to generate an electric current when exposed to photons from the sun. They are typically mounted on the top of the pole to maximize sunlight exposure.

Photovoltaic (PV) Modules

• Function: Capture solar irradiance and convert it into direct current (DC) electricity.

• Specifications: Typically composed of monocrystalline or polycrystalline silicon cells, with efficiency ratings ranging between 15% to 20%.

• Mounting: Installed at an optimal tilt angle specific to the geographic location to maximize solar exposure.

Recent advancements have pushed the efficiency of certain PV technologies beyond these typical ranges. For instance, in January 2025, Trina Solar announced a world record for their large surface area n-type fully passivated heterojunction (HJT) solar modules, achieving an efficiency of 25.44%.

Additionally, the adoption of bifacial solar modules combined with single-axis trackers has been shown to reduce the levelized cost of electricity (LCOE) by 16% compared to conventional systems. This combination allows the modules to follow the sun’s movement, optimizing energy capture.

2. Battery: The converted electrical energy from the solar panels is stored in batteries.

Energy Storage Solutions

• Types: Predominantly utilize Lithium-ion (Li-ion) or Lead-Acid batteries.

• Capacity: Designed to store sufficient energy to power the luminaire for a predetermined duration, typically 12 hours, with an additional autonomy of 2-3 days to account for overcast conditions.

• Lifecycle: Li-ion batteries offer a lifecycle of approximately 2000 charge-discharge cycles, whereas lead acid batteries provide around 700 cycles.

3. Light-Emitting Diode (LED) Fixtures: LED lights are used due to their energy efficiency, long lifespan, and high luminosity. They require less power and provide brighter illumination compared to traditional lighting sources.

• Efficiency: LEDs exhibit luminous efficacy ranging from 130 to 180 lumens per watt, ensuring high-intensity illumination with minimal power consumption.

• Color Temperature: Typically set between 3000K to 5000K to provide bright white light suitable for outdoor visibility.

• Lifespan: Rated for up to 50,000 operational hours, reducing the frequency of replacements.

4. Charge Controllers: The controller manages the energy flow between the solar panels, battery, and LED light. It ensures the battery is not overcharged and regulates the power supply to the LED light, often incorporating dimming functions and time-based lighting schedules.

• Function: Regulate the flow of electricity between the PV module, battery, and LED fixture to prevent overcharging or deep discharging of the battery.

• Features: Advanced controllers incorporate Maximum Power Point Tracking (MPPT) to optimize the energy harvest from the PV modules and may include programmable timers and dimming options to enhance energy efficiency.

5. Structural Support: The structural support components of solar street lighting systems are designed to ensure durability and stability under various environmental conditions.

• Pole: Constructed from galvanized steel or aluminum alloys to withstand environmental stresses, with heights varying based on application requirements, typically between 3 to 12 meters.

• Mounting Brackets and Fixtures: Engineered to secure components firmly, ensuring resistance to wind loads and facilitating ease of maintenance. These hold the solar panel, battery, and LED light in place, ensuring optimal angles for sunlight capture and light distribution.

Working Principle:

• Daytime Operation: During the day, solar panels absorb sunlight and convert it into DC electricity. This electricity charges the battery through the controller.

• Nighttime Operation: When the sun sets, the controller detects the drop in solar energy and switches on the LED light using the stored energy in the battery. The controller regulates the power to ensure the light remains on throughout the night.

Classification of Solar Street Lighting Systems/ Types of Solar Street Lights:

1. Standalone Systems

• Operate independently of the electrical grid, with all components integrated on a singular pole.

• Ideal for remote or rural areas where grid extension is impractical.

2. Integrated (All-in-One) Systems

• Consolidate the PV module, battery, LED fixture, and controller into a unified compact unit.

• Simplified installation and reduced maintenance due to the modular design.

3. Grid-Connected Systems

• Interface with the existing power grid to supplement solar energy, ensuring uninterrupted illumination during periods of insufficient sunlight.

• Enable energy feedback to the grid, potentially offsetting costs through net metering arrangements.

4. Hybrid Solar Street Lights

• Hybrid solar street lights are a combination of standalone and grid-connected solar street lights. 

• They are powered by a solar panel and battery combination and are typically used in areas where grid power is available but unreliable.

Advantages of Solar Street Lighting

• Eco-Friendly: Solar street lights use renewable energy, reducing carbon footprint and greenhouse gas emissions.

• Cost-Effective: Although the initial investment may be high, the absence of electricity bills and minimal maintenance costs make it economical in the long run.

• Low Maintenance: With fewer moving parts and durable components, solar street lights require less maintenance compared to traditional street lights.

• Easy Installation: They do not require complex wiring or trenching, making installation faster and less labour-intensive.

• Enhanced Safety: By providing consistent and reliable lighting, solar street lights enhance safety and security in public spaces, especially in remote or off-grid areas.

Applications:

• Urban and Rural Streets: Providing illumination for roads and pathways in both developed and developing regions.

• Public Parks and Gardens: Enhancing visibility and security in recreational areas.

• Parking Lots: Offering efficient lighting solutions for vehicle parking areas.

• Campus and Industrial Complexes: Ensuring well-lit environments for educational institutions and industrial facilities.

• Remote and Off-Grid Areas: Providing lighting in regions where access to the electrical grid is limited or non-existent.

• Airport Lighting: Mobile solar towers and portable lights provide safe, flexible lighting for airport tarmacs at night.

• Security Where You Need It Most: Solar lights with motion detectors enhance security by deterring theft and providing light only when needed.

Challenges:

• Initial Cost: The upfront cost of solar street lights can be high, which may be a barrier for some communities or municipalities.

• Weather Dependency: Solar street lights rely on sunlight, making them less effective in regions with prolonged cloudy or rainy weather.

• Battery Life and Efficiency: The performance of the battery can degrade over time, affecting the overall efficiency of the lighting system. Solar street lights have long-lasting panels, but batteries need replacement every 5-7 years, requiring ongoing maintenance for reliability.

• Brightness and Technical Limitations: Advancements in solar technology have improved brightness and efficiency, but traditional lighting may still be preferred in high-demand areas.

Recent Government Initiatives in India:

The Indian government has been proactive in promoting solar street lighting through various schemes:

1. Atal Jyoti Yojana (AJAY): Launched in September 2016 by the Ministry of New and Renewable Energy (MNRE) to illuminate rural, semi-urban, and urban areas inadequately served by grid power (less than 50% grid connectivity) with partial funding from Members of Parliament Local Area Development Scheme (MPLADS) Fund.

• Phase I (2016-2018): Sanctioned approximately 1.45 lakh solar street lights, with around 1.35 lakh installations completed. Covered Parliament Constituencies in Assam, Bihar, Jharkhand, Odisha, and Uttar Pradesh.

• Phase II (2018-2020): Sanctioned about 1.50 lakh lights, achieving 1.37 lakh installations by June 2022, despite challenges posed by the COVID-19 pandemic. Phase II expanded to hill states, North-Eastern states, island Union Territories, and aspirational districts. Covered 10 aspirational districts in Chhattisgarh, with installations completed in Kondagaon, Kanker, and Rajnandgaon.

• Due to the suspension of MPLADS Fund (2020-2022), AJAY Phase-II was discontinued for new sanctions from April 1, 2020.

• Objective: Enhance public safety and quality of life by providing reliable solar-powered street lighting.

• The Ministry of New & Renewable Energy (MNRE) installed 2.72 lakh solar street lights under the Atal Jyoti Yojana (AJAY), as reported by Union Power & NRE Minister R.K. Singh on March 16, 2023.

2. Off-grid and Decentralized Solar PV Applications Programme:

• Focuses on deploying solar street lighting in remote and rural regions. The installed solar street lights feature 12W LED lights with a 3-day battery backup for reliability in rural areas.

• As of July 2020, over 7.4 lakh solar street lights have been installed nationwide.

• Under Phase-III (available until March 31, 2021), a target of 3 lakh solar street lights was set. The scheme prioritizes areas lacking grid-powered street lighting, including the North Eastern States and Left-Wing Extremism (LWE) affected districts.

• The scheme provides Central Financial Assistance (CFA) with a 30% subsidy for General Category States, while the North Eastern States, hilly states (Jammu & Kashmir, Himachal Pradesh, Uttarakhand), and island territories (Lakshadweep, Andaman & Nicobar Islands) receive a 90% subsidy to support the installation of solar street lights in remote and underserved areas.

3. Mukhyamantri Gramin Solar Street Light Yojana in Bihar:

• In September 2024, ITI Limited secured a contract worth approximately ₹300 crore from the Bihar Renewable Energy Development Authority (BREDA) to supply and install 1,00,000 solar street light systems  under this scheme.

• However, as of August 2024, only about 20% of the target has been achieved, with challenges such as reluctance of local officials to make advance payments and concerns over the quality of installed lights contributing to the delays.

4. The Off-grid Solar PV Applications Programme by MNRE aims to provide solar power solutions in areas with limited or unreliable grid access. Under the National Solar Mission (2010), a target of 2,000 MW of off-grid solar capacity was set for 2022, implemented in three phases:

• Phase-I (2010-13): 252.5 MW sanctioned, 117 MW installed.

• Phase-II (2014-17): 713 MW sanctioned, 345.5 MW installed, focusing on rural applications like solar pumps and study lamps.

• Phase-III (2018-21): 20.09 MW sanctioned, 15.67 MW installed, covering solar streetlights and power plants for government institutions.

As of December 2022, the programme has facilitated:

• 84.59 lakh solar lamps/lanterns

• 5 lakh solar pumps

• 9.44 lakh solar streetlights

• 17.23 lakh solar home lighting systems

• 217 MWp of solar power plants

Standalone solar pumps were shifted to PM-KUSUM, and solar home lights to the Saubhagya Scheme.

 Additionally, 70 lakh Solar Study Lamps were distributed to students in Assam, Bihar, Jharkhand, Odisha, and Uttar Pradesh, with 60 lakh lamps distributed before programme closure.

5. SPV Street Lighting Programme for Rural Areas – Haryana

• The New and Renewable Energy Department, Haryana is implementing a Solar Photovoltaic (SPV) Street Lighting Scheme to reduce dependence on conventional power for street lighting in rural areas.

• Beneficiaries, including Gram Panchayats, Zila Parishads, and Block Samitis, can apply through district authorities, with suppliers selected via a bidding process.

• Subsidy & Cost:

– Solar Street Light (5m pole, 12W LED): ₹16,500 (₹4,000 subsidy, user pays ₹12,500) – Target: 9,000 units

– High Mast Light (7m pole, 4×22W LED): ₹1,03,265 (₹20,000 subsidy, user pays ₹83,265) – Target: 600 units

• The rate contract for procurement has been issued by DS&D Haryana and endorsed to the New and Renewable Energy Directorate, Haryana through official notification.

• The release on the LED Based Solar Street Lighting Systems was issued on October 28, 2024, as indicated by the endorsement of the rate contract by the Directorate of Supplies & Disposals (DS&D) Haryana to the Directorate of New and Renewable Energy, Haryana.

Solar street lights represent a sustainable and efficient solution for outdoor lighting. Their ability to harness renewable energy, combined with technological advancements in LED lighting and battery storage, makes them an increasingly popular choice for illuminating public spaces worldwide. Despite some challenges, the benefits of reduced energy costs, minimal maintenance, and environmental impact position solar street lights as a key component in the transition towards greener, more sustainable urban infrastructure.

Also read: Top solar energy solution providers in India