Carbon neutrality and sustainable development have been gaining increasing traction around the globe. To realize this ambitious transition, governments have launched initiatives and regulations to accelerate the deployment of solar and renewables. When it comes to the transportation sector, the construction of and upgrades to solar street lights have already proved to be an effective means to carbon reductions.
Though the benefits of solar street lights have obtained wide recognition, there are several types available in the market coming with a difference in specific construction, usage and maintenance. Choosing the right type is critical to satisfy your project's needs and generate the desired outcome.
This article will break down the pros and cons of different types of solar-powered street lights. You will also receive some tips about how to choose them accordingly.
Recapping the basics of solar street lights
No matter which type you are considering, all types of solar street lights consist of a solar panel, lighting module and fixture, rechargeable battery, and a pole. Some premium street light products also integrate MPPT charge controller, advanced Battery Management System (BMS) and/or microwave sensor for a robust and extensive application.
How these components combine and interact will determine the type of street light. Until now, there are three major types of solar street light as listed below:
- Split Solar Street Lights
- All-in-Two Solar Street Lights
- All-in-One Solar Street Lights
What are split solar street lights, and their pros and cons?
Also called "separated solar street lights" and regarded as the first-generation of solar-powered street lights, these lights generally have a solar panel installed on the top of the light pole and a solar battery hung at the lower part of the pole or buried underground. Simply put, all components of the light are distributed separately.
- Typically the most affordable solar street light option
- All parts of the light can be replaced with products from another manufacturer when a repair is not ideal.
- The battery storage is easier to approach for inspections and replacement.
- The solar panel has more flexibility to adjust for a better light absorption angle.
- Any upgrades on lighting brightness, panel power rate and storage capacity are more effortless to realize.
- Lead-acid batteries are widely used on these lights but with a bigger size, lower energy density, and shorter lifespan, requiring regular maintenance.
- The installation process may be more time-consuming and complex—more expenses on labor and materials are needed.
- Wiring is more complicated.
- The hung or buried battery may pose a greater electrical risk, and it's easier to be stolen.
- Long-term maintenance costs take up a big part in your project operation.
- The appearance is not appealing—not recommended for urban projects.
What are the pros and cons of all-in-two solar street lights?
The progress of battery technology is the principal push towards the emergence of all-in-two solar street lights.
Lithium-ion batteries and the lithium iron phosphate variant (LiFePO4) offer an upgraded energy storage solution with higher density, larger capacity, longer lifespan and smaller size. Consequently, they are integrated into the street light fixture and help to make up a more sleek look for the light. However, the solar panel is still independent of the light fixture and set up on the top of the pole.
- Have more capacity to power the street light due to the improved energy density of lithium-ion or LiFePO4 batteries—when there's no power generation.
- The rechargeable solar battery has higher efficiency, a longer lifespan, and requires less frequent maintenance.
- The battery is hard to be taken off as well as damaged by flood and heavy moisture, as compared to the hung or buried counterpart on split street lights.
- More aesthetically appealing than the traditional split street light design.
- Lower quality lithium-ion batteries may suffer thermal runaways, which would cause fire or damage to electronic devices and the lighting module.
- In general, they are pricier than the split solar-powered street lights.
- Less attractive than the all-in-one design.
What exactly are all-in-one solar street lights? What're their benefits?
Now comes the newest version! As the name implies, all-in-one solar street lights combine the solar panel, lighting module and battery storage into one, leading to the sleekest and most elegant look. Sometimes, if not told, people could even not distinguish them from the traditional grid-tied electrical street lights.
All-in-one solar street lights mirror the latest progress made in photovoltaics, battery storage, and lighting. Below are the benefits brought to you, which comprise most merits from the all-in-two introduced above.
- Power generation: Although the size of the solar panel becomes smaller, striving to cater to the integrated design, their conversion efficiency and power output would not compromise if supplied by reputable manufacturers. These panels, in most cases, will utilize efficient monocrystalline cells to ensure a reliable power generation.
- Battery storage: Similar to the all-in-two products, quality lithium-ion or LiFePO4 batteries are used for energy storage. In addition, some high-end products unite MPPT charge controller and the advanced Battery Management System (BMS) to lift up overall efficiency and performance.
- Lighting: Bright LED lighting is the norm for modern street lights today. Further than that, all-in-one street lights go for a higher standard for the lighting module's reliability, considering the impact of extra heat yielded by the integrated compact design.
- Other intelligent modules: Over the past few years, many all-in-one products have been equipped with microwave sensors, remote controllers, smart ventilation systems and many other intelligent modules, making them more competitive over other products, both solar-powered and traditional grid-tied.
Are the newer versions of solar street lights better? Which type should you choose?
The quick answer is yes and no. When all aspects are evaluated, newer versions of solar street light products are better than the old school ones.
But there's no "one size fits all" solution to suit all circumstances. The project location, climate conditions, and budget can influence the final choice during the procurement process.
All-in-one solar street lights seem perfect; they have some downsides project managers should overcome. The first one is the price. They have a higher price tag than the all-in-two and traditional split types of street lights, which may cause stress to project managers if they have a tight budget. Nonetheless, while the initial cost is high, the maintenance of all-in-one street lights is lower than that of the split solar street lights, which would offset your overall expenses to some extent.
Another thing you should be aware of is that the integrated panels on some all-in-one lights can only be adjusted alongside the lighting fixture, which may induce less flexibility. In this case, when they are installed on both sides of the street, some panels could not achieve the same efficiency since they are not faced perfectly toward the sunlight. Thankfully, the Renowise EVO solar street light has conquered this pain point by its innovative foldable design. The design offers a means for the maintenance crew to turn the panels on both street sides to the optimum angles, facing against the sun and absorbing the most sunlight. Beyond this, we can go for the all-in-two solar street lights for more possibilities of panel rotation.
Last but not least, you should factor into the installation site's climate conditions. Most lithium-ion batteries can withstand the heat in tropical areas and work well. But please make sure they come from quality suppliers; otherwise, accidents such as thermal runaways could happen, especially in extremely scorching weather. For projects located in areas with many rainy days or are prone to flood threats, solar street lights with buried batteries are not safe.
It can be expected that the cost of solar panels, batteries and lighting modules will keep going down in the future. The price gap between different types of solar street lights is becoming closer. Alongside the lithium-ion and LiFePo4 batteries being more progressive and safe, all-in-one solar street lights will garner more market share.
That said, a comprehensive evaluation of the project and product candidates is crucial for a wise decision.