Electricity is the key to the economic growth of India. Especially in this 21st century, power is an integral part of human lives, transport, and industries. India now generates around 1,160.1 billion units of electricity in the financial year 2017, up 4.71% from the previous year. According to reports, in 2020, 82% of the Indian population has access to electric power. While the government claims that 100% of the villages in India have electrical access, but a significant amount of population yet to get the regular electricity. The primary reason being those rural and outskirts parts of India don’t have the proper transport system or facility to install the power supply. And there are multiple disadvantages people are facing while using this traditional non-renewable energy as a source. One of the significant issues is the wastage of energy. Conventional street lights don’t contain any automatic sensor to “ON/OFF” the lights. So it is done manually, and many times due to negligence, the workers forget to turn the street lights off, and that causes the wastage. As stated by the International Energy Studies, the lighten initiative estimates that in 2010, the outdoor lighting in India consumed 18.1 TWh. As maintained by the current report of International Energy Studies, the public lighting energy consumption in India will increase to 13.2 TWh by 2020 or essentially double from its use in 2010. According to the report (Times of India), over 3 billion units of electricity was wasted in 2014-2015.
So renewable energy is the key to India’s electrification plan, and mini-grids with a capacity of 10 to 500 kilowatts are playing an increasingly important role. And when it comes to street lights, solar street lights are the best option to install all over India. Because the solar street lights can be easily transported all over rural India even to those outskirts parts which don’t have any proper transport facility yet. These solar street lights are also free from any kind of external cable connection, which minimizes the maintenance cost and the probability of accidents cause by electric wires both. Since these solar street lights have an auto sensor of “ON/OFF,” so it prevents the wastage of excessive energy, and it doesn’t require any sort of maintenance. And the batteries of solar street lights, especially the Lithium-Ion Phosphate battery doesn’t require any high maintenance, and it lasts more than 10 years. So that is easy to access.
A 50 KW solar grid with battery storage and a distribution reach of 5km can power small businesses, schools, two telecom towers, and over 500 homes. And that is way enough for rural villages in India.
The solar power industry is developing rapidly. The country’s solar installed capacity reached 37.627 GW as of 31 March 2020. India plans to produce 100GW of solar energy by 2022. As solar power is easily renewable and no greenhouse gas emissions are released in the atmosphere while using this solar power, so it’s the best nature-friendly source we can ever have. Solar street lights are getting popularity as a dependable source of low maintenance good products in India.
Solar Street Lights:
The whole idea of solar street light is based on maximum utilization and minimum loss of available energy. These solar street lights are not connected to an electric power grid. There is a solar panel that captures solar energy and the power cell, which restores energy. This solar panel is generally mounted on the lighting structure or integrated into the pole itself. And this energy is used to glow the street lights during the night time. By adapting the process of automation, the system provides a power-saving mode. A dark and light sensor provides the automatic “ON/OFF” facility to the solar street lights so that the solar street lights glow automatically when the surroundings become dark, and it gets turned off if sufficient light is available in the surroundings. On one way, the solar street lights can be connected through a micro-grid, which is a mini power grid used primarily for the lights, and on the other way, these solar street lights can be a stand-alone-system. Solar Street Lights unique features and easy access makes it most preferable in the rural area.
The main features of solar street light those provide the power saving mode are –
- Use of Solar Energy: Photovoltaic (PV) is the method of generating electrical energy from solar radiation. Photovoltaic energy generation involves a PV module that is constructed from the semiconductor material showing the photovoltaic effect. As the solar radiation is the most essential and significant renewable source, so if this energy can be stored in the power cell of the solar street lights in the form of electrical energy by using PV modules and later it can be used to run these solar street lights.
- Automatic ON/OFF Mechanism: The solar street lights should be illuminating when there is darkness, and in the presence of the daylight, these solar street lights should remain off. In the case of manually operated street lights, people can quickly realize to turn it “ON” as the darkness spreads but usually forget to turn it “OFF” even if the daylight rises sufficiently. So this is the classic example of unnecessary wastage of power. So the best option is the dark and light sensor, which automatically provides the “ON/OFF” facility.
- Auto Intensity Controller: The solar street lights don’t need to glow with the same intensity all the time. The solar street lights consume more energy to burn with high intensity than a solar street light glowing with lower intensity. So by controlling the intensity of solar street lights, it’s easy to save some more energy. This auto-intensity control mechanism is achieved by using a microcontroller. In this purposed model, the solar street light controls it’s intensity automatically according to the surrounding light. For example, when the sun starts to decrease in the evening, the strength of solar street lights starts increasing. And when there’s no intensity of light after evening, the solar street lights remain “ON” in full power till 12.00 am. After 12.00 am, the strength of the solar street lights is controlled by the passing vehicles on the road. That means the solar street light will turn “ON” only when the car will pass on the way. And again, it will turn off after the vehicle crossed the street. Infrared Sensor controls it.
- LED Luminary: An LED(Light Emitting Diode) contains a chemical compound that radiates light of visible range when direct current from the battery passes through it. The lifetime of LED is usually up to 50,000 hours. LED provides much higher luminance with lower energy assumptions as compared to the HPS(High-Pressure Sodium) fixture used in traditional street lights. The energy consumption of an LED fixture is at least 50% lower. Also, the wastage of energy in the form of heat is negotiable in the case of LED. So the lamp used in the solar LED street lights saves up to 50% energy as compared to traditional street lights.
Benefits of Using Solar Street Lights :
- Solar street lights can stand separately, so it is independent of any kind of electric power grid. Hence, the operation cost is minimized.
- Solar street lights have an auto “ON/OFF” sensor that minimizes its maintenance than the traditional street lights.
- The solar street lights don’t have any kind of external wire connection, so the risk of accidents related to electric wires is less in this case.
- The electricity produced by the solar panel doesn’t cause any kind of pollution.
- The energy is renewable so the energy costs can be saved.
- The entire solar street light system can be transported separately.
- As the solar street light is one time investments and it has excellent longevity, so it is more preferable in rural areas where the traditional electricity can’t reach out.
- Because of using LED luminary in solar street lights, it saves up way more energy than the HPS street lights.
- The increase of Carbon Dioxide and Carbon Mono Oxide is causing an alarming situation in the world called “Global Warming.” These solar street lights don’t produce greenhouse gases such as CO2 and CO. From recent research studies, and we got to know that this solar energy can eliminate the carbon emissions by 258 million metric tons if they are extensively used over the next twenty years.
- These solar street lights have a microcontroller and infrared controller to control the intensity of lights according to the surroundings and external light reflections, respectively. So there is no wastage of light energy.
- The lightweight design of these solar street lights minimizes the installation cost.
- Also, the solar street lights are waterproof, so it does not require any kind of extra maintenance during the rainy season. Solar street lights are dustproof too. So it can survive easily without any type of serious cost of maintenance in the areas where the dust level is higher than the normal.
- The batteries of solar street lights long more than five years easily, and it has good back up for the extreme weather conditions. Notably, lithium-ion phosphate batteries are the safest and most advanced option for the solar street light.
- No monthly electricity bills and no extra expenses for external cables or meters.
Centralized Solar Street lights and Stand-alone Solar Street lights :
- Centralized Solar Street Lights: This is really a unique approach to a solar lighting system in India. Most of the villages in India were equipped with electric poles but no street lights. In places like this, the centralized solar street lights are so versatile. Basically, in this centralized solar street light system, all the solar panels are installed in one place, usually on a rooftop of a building, and the power cells and other electronics are installed in a control room. The solar DC input gets converted to single-phase AC output (by a highly efficient inverter), which is supplied to all the connected street lights.
- Stand-alone Solar Street Lights: A stand-alone solar street light comes along with an individual solar panel integrated on the top, a power cell, and one LED light. This stand-alone solar street light is basically sold as street LED light with a battery box and a solar panel mounted on the top of a 6-9 m long pole. This solar street light is independent of any sort of external connections. So it can be transported easily from place to place.
There are three types of stand-alone solar street lights produced in India in terms of accessibility and unique features. Those are –
- Conventional Solar Street Lights: This type of solar street lights are the very first kind of solar street lights produced in India. There is a solar panel integrated on the top of the pole, and then there is the light (usually LED) attached separately to the pole. And the power cell is kept in a box that is easily detachable from the pole. Usually, Lead-Acid battery is used in conventional solar street lights. This is the minus point of this conventional solar light in India due to the frequent theft issues, especially in rural India.
- All in One Integrated Solar Street Lights: In case of improving the security issues, all in one solar street light was launched. The design and outlook are attractive enough. In this purposed model, the solar panel, the power cell, and the lights are attached together. That looks extremely handy and easy to access. This solar street light is perfect for all kinds of weather. It provides extra light intensity in no time according to the weather, i.e., there is a battery backup facility for the cloudy or rainy days. Lithium-ion batteries and lithium phosphate ion batteries, both can be used in the all in one integrated solar street lights. The installation is straight forward. And there is a thermal key in the integrated solar panel to control the temperature. But most of the cases are facing significant problems during installation of these all in one solar light. I.e., direct sunlight is needed to capture the solar energy for the solar panels, so it should be placed accordingly to the direction of the sun. But for paying attention to this issue, the position of the light is getting effected. For example, the locus of the solar street LED bulb is getting moved away from the streets. And that’s causing trouble for the passing vehicles and people on the road.
- Two in One Solar Street Lights: In this solar street light, the power cell and the battery are attached together and integrated on the top of the pole. And the light bulb is installed separately under the power cell. So, one can change the position of the solar panel according to the sunlight; still, the LED lamp can be in the perfect place to light the road. Similarly, lithium-ion battery and lithium-ion phosphate batteries are used in these two in one solar street light.
Different Kind of Batteries used in Solar Street lights :
There are many kinds of battery cells used in solar street lights. These batteries are intended to be versatile with low maintenance and with excellent backup power. The power cells of these solar street lights don’t require any kind of external wire connections, and the solar street light battery is also waterproof and dustproof. That means the power cells don’t need any kind of extra maintenance due to the weather changes. And these solar street lights don’t even cost any monthly electric bills and no cost of external meter or transformers. So this solar street light is one time investment. Even solar batteries last longer than 5 years easily. Here are some examples of batteries used in solar street lights:-
- Lead-acid Battery: This lead-acid battery is used by a wide range due to its low cost. It is inexpensive compared to modern technology batteries. But the main disadvantage is that this kind of solar street light battery needs high maintenance. And there is a risk of explosion in extreme weather conditions. This battery longs for 3-4 years. Another disadvantage of using the lead-acid battery is that since it contains lead, so it needs a bigger solar panel and a large battery, which requires a lot of space. This solar street light battery requires 12V of charging, and it is difficult to produce sufficient energy to generate solar street lights in high intensity during the rainy season.
- Lithium-Ion Batteries: This lithium-ion battery is more expensive and more compact compared to the lead-acid battery. Since it requires 3.7 volts of energy, that means the solar panel is smaller, and it lasts for 3-6 years. The only disadvantage is that there might be a chance of an explosion in extreme weather. And it’s efficiency reduces during very high or very low temperatures.
- Lithium Ion Phosphate Batteries: This lithium-ion phosphate battery is most advanced and most expensive amongst all the solar street light batteries. It requires 3.2 volts of energy, so the solar panel is the smallest, and it lasts 7-12 years. It is equally efficient during extreme weather conditions and at very high or very low temperatures. This street light solar battery doesn’t have any chance of explosion. So these lithium-ion phosphate batteries are the safest options for solar street lights.
All these solar street light batteries come with 6 months to 5 years warranty period.