One of the most abundant sources of renewable energy is the sun. How to tap this unlimited and free energy source is made simpler with solar cells or photovoltaic cells. You have probably seen solar panels attached to the pole of some street lights. These street lights are no doubt sun-powered and are experiencing complete autonomy from the grid.
A solar street light is powered by solar panels integrated or mounted on the pole. It has a smart, rechargeable battery that powers an LED lamp.
Solar street lights are one of the newest technologies which support green initiatives. They are environmental-friendly, smart and economical lighting solution. Solar LED street lights help deliver a favorable living environment with reduced operation and energy costs. Around the globe, some countries have already converted traditional street lights to LED street lights which proved to bear advantageous results.
Basic Operation of Solar Street Lights
The basic operation of solar street lights is that it automatically turns on and off at a specified parameter set into its controller that controls the circuit.
When dusk arrives, the voltage decreases to approximately 5V. This signals the LED lamp to switch on and use the electrical energy stored in the battery. When dawn approaches, the voltage rises up until it reaches more than 5V, which initiates the LED to turn off. At this point, the battery will recharge again. This process repeats every day.
Of course, there are some intricate features of the solar street light which makes it a smart lighting solution. In the next chapters, we will discuss how each component help in making solar street light work efficiently.
How Smart Solar Street Lights Work
Smart solar LED street lights are modern-day, integrated solar street lights that have enhanced features and components to control, manage and deliver effective lighting experience.
Smart street lights are designed modularly for easy installation and maintenance. They usually have a protection class of up to IP65.
How a solar street light works is as follows.
#1 The solar panel collects the sun’s energy
The PV module or solar panel detects and absorbs the sun’s light rays. In existence, there are two popular types of solar panels used in solar power industries. These are the Monocrystalline and Polycrystalline solar panel.
Monocrystalline solar panel is widely used in solar street light technologies due to its efficient way of capturing the sun’s power, even in cold weather.
The solar panel is mounted on the top part of the pole through aluminum brackets. Some designs have a certain range of flexibility by enabling the panels to be adjustable. This is to enable different solar panel positions to harness more effectively.
#2 A rechargeable battery converts solar energy to electrical energy and stores it
Solar street lights have rechargeable batteries. From the solar panel, the energy captured from the sun will then be turned oven the rechargeable battery. The battery stores the energy during the daytime and use it during the night to power up the LED lamp.
Rechargeable batteries are under the deep-cycle battery type which is designed to sustain continuous currents for longer periods of time. Hence, it can effectively discharge currents from time to time without losing its efficacy. Solar street light batteries are designed to have more than a day of charge. A typical design allowance is 5 days to sustain lighting during the winter and rainy seasons.
There are two types of deep-cycle batteries used in the solar lighting industry. These are lead-acid battery and lithium battery.
#3 A smart controller regulates the stored energy and electronically communicates with other devices
The stored energy is regulated in the smart controller. The smart controller helps control the flow of voltage and current to prevent batteries from overcharging. This component is actually installed between the solar panel and rechargeable battery to be able to accept signals from both components. The smart controller manages the signals to regulate the amount of voltage and current coming from the panels.
There are two main types of smart controllers used in solar lighting technology. These are the PWM and MPPT. Modern Solar LED street lights are equipped with an MPPT charge controlleras it a more reliable charge controller than the PWM.
As a core solar street light component, it functions to control the following:
- Dusk to dawn control
- Time control
- Motion sensing
- LVD disconnect
- Dusk to dawn
Voltage is kept under surveillance and metered. When the controller detects that the incoming voltage is low, the LED light automatically turns on. When the voltage increases, it signals the LED light to turn off.
The MPPT controller also initiates the dimming action and light intensity of the solar street light. For example, at certain times of the day, the LED light can project varying amounts of illumination as illustrated below.
- At 6pm to 7pm – 70% brightness
- At 8pm to 10pm – 100% brightness
- At 11pm to 5pm – 30% brightness
When the sensor detects people, it will automatically turn to 100% brightness even at any time of the night. Thus, energy usage is conserved.
Motion sensors can either be microwave or infrared. Infrared motion sensor detects heat from objects or people while microwave sensors let bounced signals enter the sensor.
The motion sensor is capable of detecting people up to a certain distance before opening the LED light. This can be a 5m to 6 m of distance.
Low voltage disconnect (LVD) Prevention
Overcharging affects negatively affects the performance of the battery and its life. Smart charge controllers prevent overcharging through monitoring low voltage and overcharge.
#4 A remote management software (RMS) sends signals to your device for remote monitoring of the street lights
The remote management software initiates an active monitoring of light level performance so as not to overuse wattage and incur larger costs. It provides a complete report of the solar street lighting system operational status. This also permits the owner to monitor and control each light fixture through remote access via phone, PC or tablet.
#5 Dusk till dawn street illumination with LED Light
Finally, the stored energy is used to power the LED light when the night falls. Manufacturers use an LED lamp as it is the most energy-efficient lighting source.
Note that LED lamps on solar street lights only illuminates from dusk till dawn, usually for 12 hours. Also, the brightness is regulated during those hours. As mentioned above, at peak hours, the light intensity is at its highest. A dimming effect is initiated when it’s past due the peak hours, but whenever the sensor detects people, it automatically adjusts to full brightness.
We hope that this article has helped you understand how a solar street light works. You can see how amazing this smart technology can be as compared with traditional street lights and older solar street light versions.
Heisolar is a solar street light manufacturer based in China. Feel free to contact us for more information about solar street lights. We are also happy to accept quotation requests.