Steven KwokThe transportation system is an important segment of decarbonization for both developed and developing regions today. As part of the system, the street light industry has undergone ongoing innovation to suit various project demands, bringing greener, more reliable and aesthetic products to the market. Vertical solar street lights have gained traction over the past couple of years. In this article, we will get you acquainted with this innovation and give you more details for a wiser procurement decision.
What are vertical solar street lights?
Vertical solar street lights can be categorized as one type of split solar street lights, where the lighting module (or light housing) and the panel are separated.
The adjective "vertical" is used to depict the orientation of the solar panel in solar street lights. In traditional lights, the panel is fixed on top of the light pole or light housing facing the sunlight above at a certain tiling angle. While in vertical lights, the solar panel is fixed vertically, parallel to the light pole.
How do vertical solar street lights stack up against other lights?
As mentioned, the most notable difference between vertical and traditional lights lies in how the panel is secured. When digging deep, there can be a few solar panel varieties for vertical lights.
Panel Form and Panel Type
The solar panel module in vertical solar street lights comes in different forms. The panel can be sliced into four pieces of bands and then embedded on the four sides of the upper part of a square light pole. Or the long panel bands can be assembled on a square, hexagonal or other polygonal tube structure; then, the structure is encased around the pole.
The majority of these panels adopt mono-crystalline solar cell technology. Still, some may use flexible thin-film solar panels (e.g., CIGS panels) since they work well in low and high-temperature or can be curved and fashioned into a cylinder panel module creating a more elegant appeal for the street light.
In some vertical lights, the photovoltaic layer of the panel is sandwiched between two pieces of tempered glass, forming a bi-facial crystalline solar panel and installed adjoining to the pole, which allows energy conversion from both sides.
Conversion Efficiency and Power Output
The conversion efficiency of the panel in solar street lights is largely determined by the technology it is used. Technically, mono-crystalline panels have an efficiency range of 15%-24%; bi-facial solar panels can generate 10%-30% more energy than conventional mono-facial mono-crystalline panels. Most thin-film solar panels used in vertical lights offer lower efficiencies, but their bendability and small temperature coefficient generally somewhat compensate for this downside, which is better suited for applications in particular scenarios and climates.
Under the same conditions, power output is determined by the area of the panel and the amount of sunlight that arrives.
Because the panel in vertical solar street lights is set up parallel to the long light pole, it offers greater flexibility to extend the panel for higher output. In contrast, increasing power output in this manner is greatly constrained in traditional lights. Expanding the panel size can either increase the risk of the tilting panel being blown down by strong wind or bulk up the light housing creating a bloated look.
The ideal tilting angle for solar panels to capture sunlight falls into the range of 30 to 45 degrees if the project is located in the northern hemisphere. The panel in most traditional street lights can be adjusted to reach this range. And the palm tree solar street lights on both sides of a two-way road can even have panels face at an ideal angle simutaneously. But it is not feasible in vertical lights. Manufacturers should use more efficient solar panels and expand the panel size to obtain a higher overall output.
Maintenance and safety
Dirt and bird droppings are not easy to accumulate on the vertically set panels, which not only helps to cut down labor costs for panel cleaning but maintains a stable output to power the light and charge the battery.
Since most vertical solar street lights employ several pieces of panel bands to generate power, the costs to replace a damaged panel are technically lower. In contrast, technicians must replace the whole, large panel in traditional lights despite minor damage on the panel.
As we already mentioned above, the panel in traditional lights is large and set at a certain tilting angle, supported by the pole. It is comparatively easier to be blown down under strong winds in certain regions, posing safety issues for the vehicles and passengers-by underneath. Though the panel on traditional all-in-one street lights is secured more firmly on the housing, it does add weight to the all-in-one housing module leading to similar risks.
Luckily, the panel in vertical lights is in a narrow form and adheres closely to the base structure, parallel to the pole and perpendicular to the ground. It works well in withstanding and unloading wind force, strengthening the safety of the application.
Aesthetics
Many solar street light products on the market still present a bulky impression with huge panels for buyers, which is especially the case for first-generation split or even all-in-two lights.
Regardless of how the vertical panel is installed, the narrow design exerts a slimming effect on the street light without compromising energy output, being an excellent choice for projects with high aesthetics pursuit.
Illumination Choice
The illuminance a solar street light can provide for the roadway underneath is one of the key metrics to consider during the procurement process. Though this is directly linked to the lighting device's luminous efficacy, power rate plays a fundamental role here.
The panel in vertical solar street lights has more room for expansion. Manufacturers can prolong the height/length of the panel to obtain more conversion area for higher power output without inducing serious risk during harsh climates.
The higher output is capable of powering a high-power light and charging a large-capacity battery. Ultimately, the illumination choice for these lights is much broader.
Benefits and not-so-good points of vertical solar street lights
Through the comparisons above, we can see there are many benefits that come with vertical solar street lights. But you should also weigh up the not-so-good points for an informed decision.
Benefits
In a nutshell, vertical solar street lights have more freedom to adopt diverse types of efficient solar panel technologies and reap different power outputs to satisfy the energy needs of the lighting module.
The vertically set panel gives a brand-new appeal for solar street lights. There is no need to prop up a heavy, unlovely panel on top of the pole, or the light housing would not necessarily be molded bigger only to hold and fix the panel. The whole light becomes slimmer and more elegant, giving out a more pleasant visual appeal while operating in a "net-zero" manner.
Not-so-good points
Though attractive enough, the major downside of these lights may be their relatively higher costs, attributed to more panel materials would be needed since the panel cannot face the sunlight at an ideal angle which should require a larger area and more efficient technology for energy conversion. In addition, more panel pieces and accessories contribute to more labor and time needed for assembling, which could ultimately add up to the total cost.
In Summary
Vertical solar street lights showcase a wise design to lessen the impact of the black or blue, dull, unpleasant look of panels on the overall aesthetics.
Praise for this brilliant design that transcends the realm of transportation projects, spreading its wings to diverse modern applications such as industrial parks and parking lots. You don't want to miss this game-changing innovation!
