A solar panel is an essential component of a solar street light system as it allows the light to operate using clean, solar energy instead of fossil-fueled power.
The competitiveness of solar energy as a renewable power source depends significantly on both the conversion efficiency and cost of solar panels. These factors also affect the popularity of solar street lights.
This article will explore the various types of solar panels used in solar street lights and discuss the benefits they provide.
Briefly recapping the evolution of solar panels
The first practical solar panel was invented in 1954 by researchers at Bell Labs. Since then, solar panel technology has constantly evolved, centering on the mission to improve efficiency and drive down costs. Since the advent of first-generation crystalline silicon solar panels, the solar panel industry has progressed toward developing and testing various materials and manufacturing techniques, rolling out a series of varieties, including thin-film, bifacial, PERC, and other types of solar panels.
Along with efficiency and cost, solar panels offer different looks and electronic and physical features, enabling various applications and performances of solar street lights.
Types of solar panels used in solar street lights
Crystalline Solar Panels
Polycrystalline and monocrystalline are two primary forms of crystalline solar panels. Monocrystalline solar panels are made from single-crystal silicon, which is grown in a cylindrical shape and sliced into thin wafers. Then these wafers are processed into individual cells that are wired together to form a panel. In contrast, polycrystalline solar panels are made from multiple silicon crystals. The silicon is melted and poured into a mold, which produces square or rectangular wafers for later manufacturing procedures.
Monocrystalline solar panels are black, while polycrystalline panels are blue. Monocrystalline solar panels have higher efficiency (15% to 22%) but at a higher cost than the latter. But over time, the costs of monocrystalline panels have decreased dramatically due to advances in technology.
Monocrystalline panels have now captured a significant share of the panel market for solar street lights, and you can hardly see polycrystalline panels in these lights. Monocrystalline panels are versatile and can be used in a variety of solar street lights, from split style to all-in-two and all-in-one models.
PERC Solar Panels
PERC solar panels are a modified version of crystalline panels, which can produce 10%-30% more energy. They have a passivation layer on both the front and back sides of the cell, which reduces surface recombination of electrons and holes, thereby improving the efficiency of the panel. This technology also includes a rear contact design that allows for more light to be absorbed and converted into electricity.
The popularity of PERC solar panels has risen sharply over the past few years. Its adoption in solar street lights helps improve energy conversion efficiency, capable of powering higher-power lighting modules. That is to say, you can get the same power using a smaller and more compact panel while contributing to the light's aesthetic value.
Bifacial Solar Panels
Bifacial solar panels are based on crystalline silicon solar technology. In a bifacial panel, the light absorption layer is sandwiched between two layers of tempered glass or transparent plastic materials. This design allows for increased energy production and improved performance in certain conditions. Studies show that the average efficiency of bifacial solar panels is about 20-30% higher than conventional panels when there are high levels of diffuse sunlight and reflective surfaces.
Since bifacial panels convert energy from both sides, they are an ideal choice to be employed in solar street lights for a higher energy yield. They are either secured on top of the light pole or light housing, or installed vertically clinging to the pole.
However, this application poses strict requirements for the material quality and encapsulation techniques; otherwise, the panels could be more prone to damage, especially under harsh climates.
Thin-Film Solar Panels
Though already invented several decades ago in the 1970s, thin-film solar panels have only become the latest hot spot in the solar street lighting industry in the past few years.
These panels are praised for many benefits, including lower cost and a more sustainable manufacturing process. But the points to be introduced below make them serve as a remarkable innovator for the industry.
Thin-film solar panels are lightweight and flexible; they are also bendable and provide many possibilities for panel module design in street lights. Vertical-style solar street lights commonly utilize these panels, which can be installed in different ways. First, they can be embedded on the four sides of a square light pole. Second, they can be processed into lathy bands and assembled into a polygonal tube structure or rolled into a cylinder structure, and then encased around the pole. In these manners, thin-film panel technology gives solar street lights a sleek and modern appearance that aligns with contemporary aesthetic sensibilities.
Another advantage brought by thin-film panels is that they can maintain good efficiency in lower light conditions such as cloudy or overcast days. Lastly, they hold impressive temperature coefficients, which means they are less sensitive to temperature changes and their efficiency would not decrease as much in hot weather.
Other solar panels
All panels can find their place in this industry! Technically, other panel technologies, such as IBC and HJT panels, can be used in street lights. But aside from efficiency, the cost is a crucial determining factor, especially considering the extra expenses of fashioning the standard models into those ones ideally used in street lights without mass production and the potential unexact maintenance costs for these newer panel technologies in the long run. Take the ones just mentioned as an example; IBC and HJT panels are more expensive than PERC panels, making their applications nearly a rarity in the street light industry at present.
Comparison chart for different panels used in solar street lights
When evaluating solar panel technologies, the top considerations are typically conversion efficiency, power output and cost. These factors are key indicators of a panel's overall performance and value as they impact what type of lighting module the panel can power, how long the panel takes to charge the battery and more.
In modern times, when solar panels are utilized in street lights, it's necessary to consider factors beyond just functionality. Aspects such as flexibility and aesthetic value should also be taken into account since they impact the overall design and look of the light fixture. When deploying street light projects in areas with extreme weather conditions, it is also important to pay closer attention to weight and the mechanical load of the panels. These are crucial factors that should not be overlooked.
We've created a comparison chart to provide you with a general overview of the features and benefits of various panel technologies used in solar street lights. This will help you better understand the differences between them and make an informed decision.
|c-Si Panels||PERC Panels||Bifacial Panels||Thin-Film Panels|
So which type of solar panel is most suitable for use in solar street lights?
It's important to understand that solar street lights are a system of interconnected components. The selection of the solar panel affects both the lighting and battery storage modules, and ultimately determines the functionality of the entire system.
Though efficiency, power output and cost may matter the most, other associated features and specs as well as project environment and requirements, will also play a role in the decision process.