Solar street lights are raised light sources which are powered by solar panels generally mounted on the lighting structure or integrated into the pole itself.
The solar panels charge a rechargeable battery, which powers a fluorescent or LED lamp during the night.
Features
Most solar lights turn on and turn off automatically by sensing outdoor light using solar panel voltage. Solar streetlights are designed to work throughout the night.
Many can stay lit for more than one night if the sun is not in the sky for an extended period of time.
Older models included lamps that were not fluorescent or LED. Solar lights installed in windy regions are generally equipped with flat panels to better cope with the winds.
Modern designs use wireless technology and fuzzy control theory for battery management.
The street lights using this technology can operate as a network with each light having the capability of performing the turning on and off of the network.
Components
Solar street lights consist of four main parts:
1. Solar Panel
The solar panel is one of the most important parts of a solar street light, as the solar panel can convert solar energy into electricity that the lamps can use.
There are two types of solar panels commonly used in solar street lights: mono-crystalline and polycrystalline.
The conversion rate of mono-crystalline solar panels is much higher than their poly-crystalline counterparts. Solar panels also vary in wattage systems.
2. Lighting Fixture
LEDs are usually used as the primary lighting source of modern solar street lights, as the LED will provide much higher luminosity with lower energy consumption.
The energy consumption of an LED fixture is at least 50% lower than the HPS fixture counterpart which is widely used as the lighting source in traditional street lights.
A lack of warm-up time in LEDs also allows for use of motion detectors for additional efficiency gains.
3. Rechargeable Battery
Batteries will store the electricity generated by the solar panel during the day and provide energy to the fixture during the night. The life cycle of the battery is very important to the lifetime of the light and the capacity of the battery will affect the backup days of the lights.
There are two types of batteries commonly used in solar-powered street lights- gel cell deep cycle batteries as well as lead acid batteries. Lithium-ion batteries are also popular due to their compact size.
4. Pole
Strong poles are necessary to all street lights, especially to solar street lights as there are often components mounted on the top of the pole: fixtures, panels and sometimes batteries.
However, in some newer designs, the PV panels and all electronics are integrated in the pole itself. Wind resistance is also a factor.
In addition, accessories do exist for these types of poles, such as a foundation cage and battery box.
Solar street light at the bus stop
Each street light can have its own photo voltaic panel, independent of other street lights.Alternately, a number of panels can be installed as a central power source on a separate location and supply power to a number of street lights.
All-in-one type solar street lights are gaining popularity due to their compact design which incorporates all of the parts necessary in a compact manner including the battery.
Advantages and Disadvantages of solar light
Advantages of solar street light
- Pollution reducing and energy saving:
There is a global awareness now amongst people and authorities regarding the importance of using resource-efficient and environmentally-friendly energy sources.
Solar street lights use no fuel to operate and work purely on solar energy. Solar energy is unlimited and imperishable and is the perfect green lighting solution.
Non-renewable energy sources like coal, gas, oil, etc. can eventually run out.
People are becoming conscious about the fact that the use of solar lights helps in reducing the carbon footprints of individuals, homes and businesses.
- Cost-effective:
Solar street lights are a better investment option considering the capital plus the operation and maintenance costs.
Since these lights are dependent on solar energy, there is no need to pay for your electricity every month. Compared to traditional street lights, solar street lights offer long-term benefits.
The lights are wireless and independent of any utility grid so no operational costs are incurred in the installation of these lights.
Since no manual intervention is needed after the installation, you may save money in maintenance costs also.
It is important to also remember that solar street lights are capable of illuminating throughout the night irrespective of power cuts and harsh weather conditions.
- No complicated power facilities:
Solar street lights are independent in nature and are not connected to your electricity provider.
There is only very minimal cabling required to connect the solar panel to the luminary and there are no external wires used outside or at the base of the pole, so they do not pose any threats of accidents.
Overheating, electrocutions or strangulation are out of the question when it comes to solar street lights.
Usually, the commercial power lighting projects are time consuming and complicated since they involve foundation work of cables, digging, cable pipe laying, cable threading inside pipes and ditch landfill.
All these procedures require a lot of labors and equipment. Moreover, there are additional costs on the transformer, distribution cabinet, and switch board also.
However, each solar lighting system is an independent unit and do not need any trenching, cable laying or other similar procedures, saving time, money and labor.
- No interdependency weaknesses:
Traditional grid electricity uses a high level of interdependency.
Interdependency of cables simply means problems in one area can affect many other connected cables and affect the whole power supply.
This is not a concern at all in solar street lighting as each unit is an independent power generating system and if one light does not work, you need to check and fix that single unit only.
- No cable costs or cable theft:
Cable theft is a common problem in remote areas and laying cables and transportation of materials to those areas can cost you dearly.
These issues can be completely avoided when the traditional lights are replaced by a solar lighting system.
Since each unit is independent and free from any cable connection, there will be no cable to steal. In case a solar-related theft occurs, it will not affect the operation of any other unit in the system. This helps in reducing any potential losses to a minimum.
- Intelligent control, easy installation and maintenance:
Solar street lighting uses an impressive dusk-to-dawn feature and is controlled by built-in intelligence. The whole installation process is simple and time-saving.
The procedure requires only basic stools and minimum labor, making the process safe and economic.
Compared to conventional street lights, solar street lights require very minimal maintenance. Apart from cleaning and doing a few inspections once in a while, there is nothing much to do to ensure its longevity.
- Available in wide ranges:
Solar lighting technology has evolved over the years and researchers and scientists are still working towards making the panels more effective.
In the future years, solar panels prices are expected to be less expensive. There is a variety of solar street lights available now with different features, sizes, types, styles, capacities, etc. and are aesthetically designed to suit your functional needs.
Disadvantages of Solar street Lights
- Expensive than conventional lights:
Solar street lights in comparison with regular street lights require higher initial investment.
People usually hesitate to invest worrying about this but not realizing in the long run, the actual cost of solar street lights is relatively much lower considering the electricity, operational and maintenance costs and the longer life cycle of solar street lights.
- Risk of theft:
Since the lights are non-wired and costly, the risk of theft is higher compared to conventional street lights.
Even though there is no risk of cable theft, the luminary and panel can be easily stolen and the components have relatively higher monetary value.
- Occasional inspection when placed in extreme weather conditions:
In extreme weather conditions, the solar panels may not function very well which can lead to reduced energy production. Snow, dust or moisture can get accumulated on horizontal solar panels affecting the performance of the PV panels.
The users are always encouraged to install the panels at an angle to avoid water accumulation; however, it is also suggested to check the panels and other parts of the light frequently to extend the life cycle of the system.
- Replacement of batteries:
The modern lithium batteries used in solar street lights have long life compared to batteries used in earlier years.
Nonetheless, rechargeable batteries can get exhausted over time and must be replaced a few times within the lifetime of the solar street light fixture.
You need to include the replacement cost as part of your maintenance cost while calculating the overall investment to purchase a solar street light.
The most common advantages and disadvantages of a solar street lighting system have been laid out here and it is obvious that the overall pluses outweigh the minuses.
Across the world, more and more people are switching to solar energy and taking a huge step towards being environment friendly.
It is time that you understand both the pros and cons and decide whether it is worth investing in solar energy. Being a part of this revolution can help not just our generation but also the generations to come to live in a clean, safe, and healthy environment.