The use of street lights was first recorded in the 4th century B.C. Different types of light sources were used over the years such as oil lamps, candle lights, lanterns, gas lamps and electric lighting. Low-energy prismatic lights were replaced by high-pressure sodium lamps in the 20th century. The latest street lighting technology uses LED that emits a white light instead of the earlier yellow. According to researchers, traditional street lights can create carbon dioxide emissions up to 6%. One of the main reasons why the use of solar energy is being encouraged is that solar street lights bring down greenhouse gas emissions by over 50%.
A significant part of municipal energy is consumed for street lighting and its overall operating cost. Street lighting is a primary concern for public authorities in developing countries as it is important for economic and social stability. Street lights should be well designed and energy efficient to permit users to commute at night with good visibility while reducing energy use and operational costs and enhancing the appearance of the area. Needless to say, poorly designed street lighting system can lead to poor visibility and light pollution. We can often see many burned-out lamps on our streets suggesting less safety in the particular area. Inadequately maintained street lights consume large amounts of energy and financial resources.
Working principle
Solar street lights deliver lighting without being connected to an electrical grid. Solar panels harvest the solar energy during the day and convert it to electrical energy which is stored in a battery system. Solar charge controllers regulate the flow of current and voltage. The stored energy is distributed during the night to power the LED lighting.
Conventional street lights operate using a standard electrical grid which generates energy from non-renewable sources. They are carefully planned and connected in a series design. Conventional street lights are required to be connected to a main supply and powered from high-voltage AC mains.
Safety
Solar street lights do not pose any cable-related accidents since the poles are wireless and are independent in nature without any electricity cable connection. There are no protruding external wires and there is no risk of overheating.
Conventional Street lights are connected with a lot of wires and the cables are directly connected with electricity. Risk of electrocution and high chances of a short circuit are always there. During the installation process, there is also a threat of strangulation to the workers.
Installation of streetlights
Solar street lights are simple and uncomplicated to install. Since the system is wireless with independent and integrated components, the installation process is easy and can be achieved with minimum manpower and basic equipment saving both labor and cost.
Conventional street light installation demands professionals as there is an enormous amount of trenching and cable laying required to connect to grid lines. A large number of workers need to be hired due to the laborious and time-consuming installation process. Along with this, the installation cost also includes expense in installing transformer, distribution cabinet and switch board etc.
Lighting
Solar street lights use LED lamps which deliver brighter light for less energy used. LED lights are less prone to failures and the working hours are much higher when compared to their contemporaries. LED lights are well known for their high efficiency and longer lifespan.
Conventional street lights typically use high pressure sodium lamps due to their ability to produce bright light. Metal halide bulbs are also used in many countries for street, stadium and parking lot lighting. Halogen bulbs are also used since they last longer than incandescent bulbs. Not all are able to afford LED lighting due to their high pricing when compared to other lights.
Impact on the Environment
Solar street lights operate using unlimited renewable energy which is economical and safe for the environment. Usage of solar energy helps in eliminating carbon footprints. Solar energy is available in abundance and is free for all. There is no light pollution and no cost for the energy used. Most of the solar street lights have motion sensor and dimming options which help in saving energy which in turns extends the life of the street light system.
Conventional Street lights use electricity which is produced from non-renewable sources and this leads to production of carbon dioxide which is harmful to the environment. Also, HPS and metal halide lamps contain mercury which is toxic to the environment. If all the street lights are converted to solar lights, global electricity consumption could be reduced by 52% avoiding the production of carbon dioxide by 735 million tons.
Initial investment and future cost
Solar street lights require a higher initial investment in comparison with the conventional streetlights because of the higher cost of solar panels and batteries. But considering the fact that solar street lights harness free solar energy, in the long-term, they are more cost-effective. The plug-in-and-play installation does not require any extensive labor or tools. Solar street lights demand almost no manual intervention after installation and save money in terms of operation and maintenance.
Conventional street lights may cost more for installation, maintenance and electricity over a time period. In case of new installations, traditional street lights need cabling and trenching to connect to grid lines. This creates extensive additional costs and maintenance cost is another concern. If sodium bulbs are being used, they have a life span of only 5 years and the replacement cost also has to be considered. Interdisciplinary weakness can damage many units at a time and the replacement cost can be quite high.
Maintenance
Solar street lights do not usually require any type of maintenance. After the installation, no extra intervention is required to maintain the system. Only luminary cover needs to be cleaned once in a while for better light output. Most of the dust or dirt on the panels is washed off during rains. The panels and the batteries usually come with a longer guarantee and need to be replaced only when they are out of that period.
Conventional street lighting requires constant monitoring. The defective lamps, accessories and wires need to be replaced whenever required. It is always better to rectify cable faults as early as possible. Regular maintenance of fuse box and service cabinet is also important to look for loose connections and to check if the cables are connected properly. Constant monitoring and metering are done by trained personnel.
There is a massive potential to improve lighting quality while reducing costs and environmental impacts and solar energy is one of the easily available energy sources. Depending on the project’s budget and one’s requirements, you may choose the type of street lights. There are significant differences between solar and conventional street lighting systems and once you understand the reasons why many individuals and countries are turning to solar-powered lighting, it will be easier for you to compare the options that are available and choose the one that fits the bill.