Solar technology applications have been spreading all over the world as utility platforms to power buildings, vehicles, LED street lights and other devices. When it comes to solar LED street lights, it is very important to take a closer look at how the system is designed and what components are integrated together to deliver light performance from clean energy sources.
Introducing smart technology in the solar street lighting system is an essential step forward in ensuring off-grid system reliability and durability. Dedicated cloud software and wireless communication technology gives power to the user to control, manage and pro-actively maintain every solar street light via PC, table or smart-phone. Check out this article to find out how smart technology improves solar street light performance.
In this blog, we provide a quick overview of the core components used in the design of solar street lights. Knowing all the technical considerations will help you analyze which solar street light is the right fit for addressing your energy needs.
SMART SOLAR STREET LIGHT DESIGN
Every smart solar street light system consists of several core components. The functional off-grid system depends on the quality of each component, the technology used in the system and the management of the solar street light over time. Choosing the right smart solar street light specification is not an easy task, therefore you need to know all the system design nuances before discussing the technical proposal with a solar street light company. We have covered in detail what are the right questions to ask when considering solar street light proposals in this article.
SMART SOLAR STREET LIGHT COMPONENTS
- • Solar Panels
- • LED Light
- • Solar Rechargeable Battery
- • Smart Solar Controller with inbuilt wireless communication
- • Remote Management Software
- • Motion Sensor
- • Pole
- • Interconnecting Cables
SOLAR PANELS
Solar street lights are designed to absorb energy during the day. This energy is used by the off-grid system to power LED lighting during the night. The solar panels start working as soon as the sun is up while the LED lamp automatically switches off after the sunrise. The process is reversed when the sun goes down. The solar energy detection can be done either through solar panel sensing (this functionality works by detecting solar panel voltage which will increase immediately when sunlight hits the panel and vice versa) or through an astronomic clock built in the solar system (microchips using latitude and longitude clock combined with real time clock to decide when to flip a switch). The main function of the solar panels is to convert sunlight into electrical energy through photovoltaic solar cells. This energy is then stored in solar rechargeable batteries.
WATCH VIDEO ON TWITTER: HOW SOLAR PANELS ARE MOUNTED ON STREET LIGHTING POLE IN THE WORKSHOP
There are two types of solar panels worth mentioning (we will not cover thin-film panels as they are much less efficient and not able to perform up to the task): Mono-crystalline and Poly-crystalline. Compared to Poly-crystalline, the energy conversion rate of Mono-crystalline solar panels is much more appropriate for solar street light performance. To read more detailed information on how solar panels work and function read our previous article on the subject.
Every solar street light proposal must specify:
- • Number of solar panel(s)
- • Type: Mono-crystalline or Poly-crystalline
- • Power of solar panels: Total Wattage
- • Mounting to the pole: on top of the pole, side of the pole
All of the above mentioned points rely heavily on the specific requirements and the specific location (both micro and geographical) for every project in question. For example, when considering to install solar street lights, you should always pay attention to the surrounding objects, especially if they create shading that could decrease the solar panel performance. Believe it or not, this matter is usually overseen by many solar street light users. Knowing the geographical location of the solar street light project helps in configuring the solar panel power (total Watts) and in setting the appropriate angle of the solar panel fixture.
Useful tip: If you are located in the Northern hemisphere, your solar panels should be faced south. If your location is in the Southern hemisphere, the panels should be directed towards north. In most cases, the angle of the solar panel should be between 30 and 40 degrees. The more you go towards northern locations the angle of the panel should increase. For example, if your solar street light project is in Sweden, you would probably go with 90 degrees angle of the solar panel.
LED Light
Smart solar street lights use new LED technology which delivers much higher Lumens for less energy used. LED lights with lower wattage than traditional style fixtures are more efficient and have lower power consumption while providing higher luminosity levels and zero UV emissions. LED fixtures are also less prone to failures with an average number of 50,000 working hours, whereas traditional street lights range from 5,000 to 8,000 working hours with much higher failure rate.The energy consumption rate of LED fixture is at least 50% lower than high pressure sodium (HPS) fixtures.
Every solar street light proposal must specify:
- • Type of light fixture: LED light model (you should not even consider any other type of fixture except for LED light)
- • Luminosity per Watt
- • Light distribution patterns (there are many distribution patterns available and usually they are determined based on the specific location in question).
- • Light level requirements (ex. lighting on street must be .2 foot candle average with lighting uniformity ratios under 10:1)
- • B/U/G rating and Dark Sky requirements
- • Fixture mounting height
- • Specific illumination area (ex. 1 lane street, each lane 12’ wide with no median, light pole set back 5’ from edge of street)
Click here to read more on the differences between traditional and solar street lights.
SOLAR RECHARGEABLE BATTERIES
The Solar Battery is a type of electrical battery or accumulator. Its main function is to store electricity from the solar panel during the day in order to provide energy for the LED lamp in the night. The capacity and lifetime of the battery is very important as they provide backup power for low energy periods – days without sun. A good smart solar street light system has a temperature probe that monitors the battery and optimizes its performance (battery temperature and depth of discharge voltage) to prolong battery life cycle. There are three types of batteries: lead acid battery, gel cell deep cycle battery and absorbed glass mat (AGM) battery (also called starved electrolyte). AGM and Gel technology are preferable for solar systems.
Every solar street light proposal must specify:
- • Type of solar battery
- • Total amperage hours
- • How much system autonomy can be achieved with the battery to ensure LED light performance. Most solar street light systems do not provide more than 3 nights of battery storage. With smart technology, such as real-time remote control and monitoring of discharge values, battery data coming from temperature probes and overall energy optimization, the off-grid system will ensure reliable performance all year long.
- • Mounting: Battery box (construction material), under ground, on top of pole etc.
- • Useful Tip: Bury the batteries underground if you want to prolong their life cycle. Solar batteries do not perform well if they are exposed to extreme temperatures. The soil is a perfect isolation to keep optimal temperature both during winter and summer, so buring the battery deeper in the ground is a good solution.
SMART SOLAR CONTROLLER & COMMUNICATION
The solar controller is the heart of the solar system. This device decides when to switch on or off the lighting and charging. Smart controllers have built in functionalities to control lighting, dimming and battery charging. The smart controller prevents the solar battery from overcharging and undercharging. By receiving the energy from solar panels it continuously charges the battery during the day. During the night the controller supplies the stored power to run the LED street lights. Smart controllers can support single load or multiple loads.
Smart solar controllers provide excellent energy generation, performance optimization and monitoring of each street light unit via cloud based software. The smart controller has a built-in communication network and dedicated software for control and proactive maintenance of the entire street light network to achieve the highest LED light performance 24/7, 365 days per year.
Today we have many different protocols that would enable wireless communication and control of the solar street light, such as: wireless LAN, zigbee, sigfox or Lorawan. Smart controllers are designed to communicate data, either via SIM card in each smart solar controller (having small number of units involving up to 10 solar street lights) or via cellular gateway device (having large number of units involving more than 10 solar street lights), to enable data transfer from each system component to an online cloud software with a user interface. The smart solar controller, motion sensors, the cloud based software and the type of communication network constitute the smart technology aspect of solar street lights.
Every solar street light proposal must specify:
- • Type of solar controller (PWM, MPPT, SMART). If you want to achieve maximum performance and longevity, consider going with smart solar controller with built-in communication which enables interactive control and monitoring of the system in real-time. If you would like to know more about all the benefits of smart solar controllers, check out this article: Solar Street Light:” How Smart They Can Be”
- • Capabilities and functions: To properly size your controller you need to know the following:
- ○ Solar Panel Wattage
- ○ Battery voltage ( 12 V, 24 V or 48 V)
- ○ Amperage: To choose a perfect amperage for your solar controller, consider using Ohms Law comes. You need to divide Solar Watts with battery bank voltage. For example, 200 Watts Solar Panel / 12 Volts Battery = 16 Amps. Therefore, you need to choose 20 amps controller (most controller are 5, 10 , 15 , 20 or more amps).
- • Type of battery charger, secondary power, LED lamp drivers installed, other drivers and protection (against over or undercharging, short and open circuit)
- • Mounting and installation details
- • System connections (detailed layout of inputs and outputs)
- • Type of communication network & protocols
REMOTE MANAGEMENT SOFTWARE
Cloud Software gives you the power to monitor, manage and proactively maintain solar street lights over the Internet. Weather forecasting algorithms and load management enables you to set up and change lighting profiles in real-time with dimming and motion detection to ensure LED lighting, regardless of weather conditions. The software monitors your off-grid street light system day and night and sends alerts when needed to identify issues and deal with problems in real-time. With continuous capture of data, the software can pinpoint the right action to take to keep the solar street lights operating at the most optimal efficiency levels.
WEBINAR: How to control your solar street light and make it functional 365 days
Every solar street light proposal must specify:
- • Details about training for software usage
- • Software and monitoring fees (if any)
- • Software licensing and related
MOTION SENSOR
Motion sensor is a crucial part to have in the system since it is used to provide lighting when movement is registered. Motion detection allows for a unique possibility to set lighting schedules based on your specific preferences at different times during the night, including motion detection for pedestrians or vehicles. The main objective is to conserve energy during the night.
Every solar street light proposal must specify:
- • Type of motion sensor
- • Specification of functionalities
POLE
Strong pole is essential for every street light. Since heavy components are mounted on top of it, like the solar panel, fixtures and sometimes even the batteries. The construction material used in the production of the pole and the static analysis before deployment are also very important for consideration. Innovative modular design of street light poles reduces transportation and logistics costs and decreases the construction difficulties during installation.
Every solar street light proposal must specify:
- • Type of pole material: aluminum, steel, concrete, composite.
- • Placement: anchor base or direct burial
- • Static report – supporting the total weight of the mounted components (wind loads for particular installation location)
INTERCONNECTING CABLES
The battery box, LED fixture and solar panel are interconnected with cables. The cable for this system includes connecting the PV module to the controller, and then connection from the controller to the battery and LED lamp. The cable size and lengths depends on the current that goes in the lights and the height of the pole.
Every solar street light proposal must specify:
- • Installation manual with exact procedures for the interconnecting cables
- • Specification of the interconnecting cables
We hope that after reading this blog you will have a better understanding of smart solar street light design and components. Contact us If you have any questions on this topic. Also, don’t forget to post your views and feedback on this blog in the comment section below. For additional questions, visit this Q&A page. If you are interested to receive new information and articles, subscribe to our blog or follow Lightinus on Facebook and Twitter.