Are Solar Street Lights Worth Choosing From Among Many Lighting Fixtures?

Do you know that there are streetlights that do not require grid power for operation? All they need is good sunlight during the day to work at night. Solar streetlights use a system of solar panels, electricity storage, and control systems to provide lighting at night. It enables off-grid lighting systems in remote areas with minimal maintenance and installation activities. They also reduce the lighting load from the grid, which accounts for 20% of the nation's consumption.

Solar streetlights have programmed PWM or other controllers that adjust LED brightness based on battery voltage, date, and real-time clock data. They are a complete lighting system with electricity storage, solar energy converters, controllers, drivers, lighting elements, and mechanical fittings.

Types Of Solar Street Lights

As technology progresses and feedback from solar street light installations piles up, various designs emerge to cater to field conditions. LED lamps have shown promising results in solar street lights. Owing to their directional light characteristics, they provide the best lumens per watt power consumption. Considering the solar street light design manufacturers divide them into four major categories:

1. Integrated All in One Solar Street Lights

As their name suggests, these solar lights have all the systems integrated inside an enclosure. It includes the solar panel, battery, driver, controller, fittings, and heat sink. The installation of integrated lights is simple and convenient, as there is no need for additional wiring or complex fittings. The integration of components is favorable for sites where quick installation is necessary. These lights have a convenient pole mounting system with quick fastening and electrical connection. A professional can set up an integrated solar street light in less than a minute.

The integration of multiple components also leads to a sleek design. Integrated all-in-one solar streetlights offer an elegant and modern aesthetic that enhances the visual appeal of public spaces. These lights can feature proximity sensors, brightness adjustments, and excellent IP/IK ratings.

2. Modular Design Solar Powered Street Lights

What if you could change the only part malfunctioning in the light with minimum disassembly and quick installation? Modular solar-powered street lights provide flexibility in maintenance and modifications. A typical modular solar street light will have the following replaceable components:

● Solar Panel

● Lamp Shell

● LED Light Board + Optical Lens

● Controller

● Battery Pack

The modular design also enables upgradation capability with simple steps. If the company introduces a new and more robust component, the user can easily replace it through simple disassembly and replacement. Its modular capabilities make it an ideal product that supports sustainability with cost-effectiveness.

3. Split System Solar Street Lights

The initial design of solar streetlights was the split system, which was cost-effective and functional. Its simple approach with separate components allows for easy replacement and upgradation. Compared to modular designs, the split system approach takes up more space and has a visible bulkiness to the aesthetics.

Replacing components of the split solar street lights is more convenient. The use of non-specialized components allows for modifications within the budget. The buyer is not restricted to using components from the same manufacturer. However, it does have longer installation time and wiring complexities than the modular design approach.

4. Integrated Pole Solar Street Lights

Integrated pole solar street lights are ideal for applications where a luminance of 3000-9000lm is enough to light up the street. These streetlights integrate the solar panel around the circumference of the pole. They are also called wrapped solar pole street lights. All the components of the solar street lights are inside the pole, making the overall assembly sleek and aesthetically pleasing.

These lights are ideal for locations with high foot traffic or tourist attractions. However, the buyer must consider the high initial cost, as these lights come with the solar panel integrated pole, LED, control systems, and battery.

Differences Between Solar Street Light And Normal Street Light

Standard and solar streetlights differ in aesthetics, design, components, and application. Selecting either of the technologies requires careful evaluation of their differences and possible budget impacts. Here are their differences:

● Design: Solar streetlights would appear visibly bulky as they carry additional solar panels and battery systems. In comparison, regular street lights use grid power, reducing the number of components.

● Application: Normal street lights are suitable for locations with an energy grid. Solar streetlights are off-grid and ideal for remote areas without a power grid.

● Cost: A solar street light costs significantly more than a typical street light. It is mainly due to the added components and control system design.

Differences Between Solar Street Light And Solar Floodlight

Solar streetlights and floodlights vary in build quality, fixtures, light spread, and application. The differences are primarily due to the design, which uses similar internal and external components. Here are the key differences:

● Design: A solar floodlight can have a solar panel integrated into the body or installed separately, similar to a solar street light. Streetlights focus downward with lower directionality than floodlights, while floodlights provide a focused beam to an object.

● Applications: Solar floodlights light up buildings, sports fields, billboards, or security parameters.

● Cost: Solar streetlights typically require a higher initial budget as they need a robust design compared to solar floodlights. Their impact protection rating is generally higher than that of most floodlights. However, exceptions to these conditions exist in both types.

Here is a table that summarizes all the differences between regular streetlights, solar streetlights, and solar floodlights:

Features of a Solar Street Light

Finding the perfect solar streetlights necessitates evaluating their specifications. Understanding the limits is vital to finding compatibility with any lighting project. Solar streetlights are an excellent off-grid lighting system, but finding the right supplier that addresses the challenges and complexities of solar streetlights is essential. Let's have a look at the key specs of a solar street light:

➤ Solar Street Lights Lumens: Brightness, Wattage, and LED Chips

Lumens and Controlling Brightness

Lumens is a unit to measure lighting conditions. It represents the brightness of the light in numeric form. Higher lumens mean that the light will be brighter, but it will also require more power. Modern intelligent lighting systems utilize lighting and proximity sensors and timers to control brightness based on environmental requirements. These advanced LED solar streetlights have longer operational life and provide better battery backup due to advanced regulation and control systems.

Street Light Wattage and Brightness

An 80-watt solar streetlight can produce 12800 lumens of light using a design that can produce 160Lm/W. Highway lighting typically requires 10000 lumens, which makes 80 watts high enough to support the necessary brightness for adequate driver response time and awareness distance. A 20-watt solar street light is enough for pedestrians on a sidewalk. A typical solar street light for sidewalks will feature proximity sensors to adjust the lighting brightness based on traffic.

LED Chips and Lumens

Manufacturers produce many types of LED chips. The most popular and robust are SMD5050 and SMD3030 from Luxeon, a Philips LumiLEDs brand. Owing to their chip design and good heat transfer characteristics, these chips have exceptional Lm/W production capability. Ensuring the LED chips' good construction quality and design is vital in selecting solar streetlights.

➤ Solar Panel: Efficiency, Direction and Size

Solar panels are the most vital part of solar streetlights. They provide electricity to the lighting module via a battery. During the day, they convert solar power from the sun to electricity through PV (Photovoltaic) cells. The photons in the sunlight fall on the PV module and cause its electrons to move inside the PV cells. It leads to generating current that goes to the battery through wires for storage. A typical 40-80W solar street light will have a 35-65W solar panel to charge the battery.

➤ Battery Capacity: Type and Energy Density

There are many types of batteries, each with its characteristics. Lithium Li-NCM and Lithium LiFePO4 are the two popular types of batteries with varying capacities. The types of batteries directly affect their capability to store energy. However, initial budget and installation constraints can decide when selecting a type. Typically, high-end LED solar street lights will feature either of these two types of batteries:

● Lithium Li-NCM: Lithium Nickel Manganese Cobalt Oxide is a popular battery cathode material. The monocrystalline cathode material can achieve an ultrahigh volumetric energy density of over 2600 Wh/L in half-cells. Its energy-dense properties make it ideal for solar panel applications where space constraints are vital.

● LiFePO4: Lithium Iron Phosphate is another compact battery suitable for solar street lights due to its energy-dense characteristics of 433 Wh/L (1170mAh).  

➤ Backup Time: Brightness Regulation and Battery

Backup time depends on various other specifications of a solar street light. A high-end solar street light will feature control methods that decrease the brightness of the LED during times of low or no traffic. The backup time also depends on the LED chip and the driver's battery capacity and power consumption. To summarize, a modern solar street light that uses the latest battery type with modern regulation techniques will generally quote their backup time depending on the brightness levels. Here is an example of a solar streetlight from CHZ:

● Option 1: 4 hours of full power and 8 hours of sensor-based brightness.

● Option 2: 12 hours with sensor-based brightness (100% brightness when active, 30% during non-active).

These show that if the light runs in regulation control, it can run for 12 hours a day. If it uses full brightness for 4 hours, with loads of traffic and proximity sensors for brightness control for 8 hours, it can have a similar backup of 12 hours.

➤ Control Method: Sensors and Control Circuits

Solar streetlight manufacturers deploy various control methods to enhance battery backup and address environmental concerns. During the night, with low traffic, the lights will reduce brightness to ensure the circadian rhythm of humans living around the block is not disturbed. A solar street light controls light through sensors and control circuits:

Sensors

● Light Sensor with NEMA Connector

● Motion Sensing Using Proximity Sensors

● Battery Voltage Sensor

● Power Consumption Sensor

● Tilt Sensor for Solar Panel

Control Circuits

● 0-10V Dimming

● DALI (Digital Addressable Lighting Interface) Dimming

● Pulse Width Modulation (PWM)

Installation and Maintenance

Solar streetlights are long-lasting and require minimal maintenance. All the components inside solar streetlights are maintenance-free. The only time when maintenance becomes necessary is after the breakdown of an element or the cleaning of lights. Installation has also become convenient owing to the design maturity and the modular or integrated approach. As solar street lights do not require any external power to operate, they can be installed in minutes, only requiring fastening to the pole. Here is the life expectancy of the two most vulnerable components:

● Solar Panel: According to the Solar Energy Industries Association (SEIA), solar panels last between 20 and 30 years.

● Battery: A Li-NCM battery can last 1500-2000 charge-discharge cycles. On the other hand, a LiFePO4 battery has a charge-discharge cycle limit of 2500-3000. This roughly translates to 5-7 years if the battery uses 80% of its charge every day with 12 hours of use in regulation mode.

Conclusion

Solar streetlights are the best for off-grid solutions and long-term savings. The initial cost can be high, but due to modern design's reliability and maturity, solar streetlights are becoming the go-to option for most countries for street lighting. Even areas with a grid are also adopting solar streetlights. Solar streetlights are worth choosing from many other types of lighting fixtures as they provide efficiency, low maintenance, easy installation, and enhanced regulation features.