Introduction

Street lighting is not one size fits all – from highways and expressways to local roads, alleys, crosswalks and even bike lanes, different types of roads have very different lighting requirements. But no matter the scenario, these types of streets need proper lighting to ensure the safety of those who use them. Solar LED street lights and AC street lights are the two main options. This article will focus on the main advantages of solar LED street lights in road lighting, and how to correctly choose the right solar LED street lights (check to find more ZGSM solar street lights) for your project. This requires you to understand the lighting and requirements of different types of streets, and how solar lighting can meet the lighting requirements of the corresponding roads. At the same time, we will also focus on the scientific configuration method of solar street light wattage and battery capacity.

Why go with solar LED street light?

Street lights can achieve fast, accurate and comfortable visibility at night, which is helpful in reducing nighttime traffic accidents, improving traffic flow, and promoting nighttime commercial activities and the use of public facilities. In recent years, the demand for street lights in the city has mainly shifted to solar LED street lights. ZGSM believes that the reason why solar LED street lights are widely used is precisely because of these three core advantages – efficient lighting, convenient installation, energy saving and environmental protection.

Solar street lights now mostly use LED as the light source, which is usually equipped with 220lm/W and higher LED chips, so the overall light efficiency can currently be close to 200lm/W. This allows solar LED street lights to illuminate the road with lower wattage. With reasonable light distribution (What’s light distribution?), we can achieve 50W or even lower wattage to achieve M2 lighting class for main road lighting. These characteristics make the application of solar LED street lights more extensive.

The installation of solar LED street lights does not rely on traditional power grids, so the installation of solar street lights saves the need for cable trench excavation, distribution cabinet installation and transformer installation, etc. This makes solar LED street lights have great potential for application in rural areas, mountainous areas, grasslands and islands with imperfect infrastructure. In addition, its installation cost can also be greatly reduced.

Solar street lights absorb solar energy through panels and store electricity in batteries through controllers, and power LED light sources at night, which makes solar LED street lights independent of traditional fossil fuels. Taking a 50W solar street light as an example, it can reduce 150kg CO₂ emissions per year (PS: Taking thermal power as an example, 1KWH of power generation has a carbon emission of 0.7KG). Such a huge reduction in emissions is of great significance to the protection of today’s increasingly deteriorating natural environment. The figure below shows the basic composition and working principle of solar energy.

Lighting requirement for your roadway lighting

Roads can be divided into different types according to their functions and design standards. Expressways are long-distance, high-speed inter-city or cross-regional traffic arteries. They are fully enclosed (no intersections) and have high speed limits (for example, 100-120 km/h in China). Expressways are fast passages within cities or suburbs. They are usually fully enclosed roads (or only a few intersections) and have high speed limits, usually 80-100 km/h. Urban main roads are the main traffic arteries in the city, connecting the centers of various regions. These roads are usually 4-8 lanes in two directions, with isolation islands in the middle, and speed limits of 60-80 km/h; secondary main roads assist trunk roads in diverting traffic, connecting residential areas, commercial areas, industrial areas and public service areas; branch roads are used for short-distance travel within residential/commercial areas, usually 2-3 lanes in two directions, and speed limits are usually 40 km/h; rural roads connect villages, houses and farmland, with relatively few vehicles, and speed limits are usually 30 km/h. These roads together form a complex transportation network between cities, between cities and rural areas, and within cities/rural areas.

Different roads have been introduced, so are the lighting requirements for different types of roads fixed? Normally, if the speed limit is fixed, the traffic volume, traffic composition, intersection density, the presence of parked vehicles and the ambient brightness are the same, the lighting requirements for the same road type are fixed. However, when there are different parameters, the lighting standards will also be different. For example, on both main city roads with speed limits of 80km/h and 60km/h, the lighting requirements for the former are higher than those for the latter, because the speed is faster and better lighting is needed to help the driver see the road conditions clearly. For example, for urban branch roads, the lighting requirements for roads where parking is allowed are higher than those for roads where parking is not allowed, because vehicles parked next to them will interfere with the driver’s ability to see the road conditions clearly, so better lighting is needed to reduce driving risks. So is there any way to help municipal departments determine lighting standards? The answer is yes, and EN13201-1(More details about EN13201 for street lighting design) provides a clear method.

The lighting standards involved in motor vehicle road lighting include brightness level (luminance) and uniformity, illumination level around the road and residual glare limit. If the project has clear requirements for these, the lighting design (lighting simulation) can be carried out according to these requirements. If there are no requirements, it can be selected by referring to the standard EN13201-1. At this time, the parameters we consider include: speed, traffic volume, traffic composition, lane separation, intersection density, parked vehicles, ambient brightness, difficulty of navigation task/visual guidance/traffic control. For example, for a road with a design speed of 80km/h, the weight value is 1. If traffic volume is high, then the weight value is 1. If the carriageway isn’t separated(without median island), then the weight value is 1. And the junction density is <3/km, then this weight value is 0. The road is without parked vehicles, then this weight value is 1. And for other weight value we supposed that they are all 0.

Parameter	Options	Description			Weighting Value VW
Design speed or speed limit	Very high	v ≥ 100 km/h			2
	High	70 < v < 100 km/h			1
	Moderate	40 < v ≤ 70 km/h			-1
	Low	v ≤ 40 km/h			-2
Traffic volume		Motorways, multilane routes		Two lane routes
	High	> 65 % of maximum capacity		> 45 % of maximum capacity	1
	Moderate	35 % – 65 % of maximum capacity		15 % – 45 % of maximum capacity	0
	Low	< 35 % of maximum capacity		< 15 % of maximum capacity	-1
Traffic composition	Mixed with high percentage of non-motorised				2
	Mixed				1
	Motorised only				0
Separation of carriageway	No				1
	Yes				0
Junction density		Intersection/km	Interchanges, distance between bridges, km
	High	> 3	< 3		1
	Moderate	≤ 3	≥ 3		0
Parked vehicles	Present				1
	Not present				0
Ambient luminosity	High	shopping windows, advertisement expressions, sport fields, station areas, storage areas			1
	Moderate	normal situation			0
	Low				-1
Navigational task	Very difficult				2
	Difficult				1
	Easy				0

For the determination of the number of the appropriate lighting class to be applied, the weighting values for the different parameters have to be added. As per the previous section, we get the sum of weighting values Vws = 1+1+1+0+1+0+0, which we finally got the Vws =4. Because it’s a motorway, we get the M lighting class = 6 – Vws = 6-4 =2. So M2 lighting class should be used for the lighting design. For C and P lighting class, the calculation equals are similar which is lighting class C = 6 – Vws and lighting class P = 6 – Vws.

Choose the solar LED street lighting system with right watts, battery and panel

Step 1 – where should be lighted

For areas that need street lights, we must first figure out the length of the road that needs street lights, the composition of the road, the width of the lanes, the distance between the light poles, the height of the light poles, etc. They are very helpful in helping us confirm the number of lamps, wattage and lenses required. For example, a city expressway is a two-way 4-lane road (7 meters in one direction), with an isolation island (1 meter) in the middle and two-meter hard shoulders on both sides. The design speed of the road is 80km/h, the traffic volume is high, there are almost no intersections, and parking is allowed on the road. The navigational task is difficult. We can calculate the required lighting level of the road based on the knowledge in the previous section as M2. However, the project takes into account the important channel between the two cities. In order to avoid traffic accidents, the lighting is finally required to be designed according to the M1 lighting class.

Step 2 – Wattage(lumen) we need for lighting the road

The composition of the road has been determined in the first step. Then we can use this to perform lighting simulation to confirm the required wattage. Don’t believe that there are 500W or even 1000W solar street lights. Such high wattage is not needed in actual applications. Taking 200lm/w solar LED street lights as an example, ZGSM conducted a simulation and found that 100W with Single sided arrangement (More about Luminaire arrangement of street lighting) is enough to illuminate a 7-meter road (30-meter pole spacing, 8-meter pole) as per highest M1 lighting class. In addition, we should pay more attention to lumens to confirm the wattage, rather than just staring at the wattage to confirm the configuration of solar street lights. The same 100W, 150lm/W is difficult to meet the M1 lighting class. If the light efficiency is increased to 190lm/w, the M1 lighting class can be easily met. We can conclude that in solar street lights, we should choose high-efficiency LED street lights as much as possible to reduce the wattage of the lamps, and then we can greatly reduce the configuration of solar panels and batteries in the system.

Step 3 – Determine the lighting requirements

Through the first and second steps, we have basically determined the wattage of the solar system. Next, we need to confirm the working mode of the solar street light. 1. Do the street lights need to run from dusk to dawn, or only for a certain number of hours at night? 2. Can the street lights be dimmed in the middle of the night to avoid excessive lighting in the second half of the night when there is less traffic? 3. Do the street lights need to be equipped with microwave sensors to reduce system consumption and thus reduce system configuration when no one is around? 4. Will the solar lamps have access to the electricity to ensure that the lamps can still provide lighting to ensure safety when there is insufficient solar energy? When you decide on the configuration of the solar street, these questions need to be answered because they determine the size of the system configuration. For example, a configuration that works 100% all night is definitely much higher than a configuration with microwaves or timer dimming, which cause the price will be higher as well (Why solar street light prices differ a lot?). For solar street lights with mains access(electrical grid), we can also appropriately reduce the system configuration because we do not need to increase the panels and batteries to reserve power to ensure that the lamps work normally on rainy days.

Step 4 – Calculate the configuration and get the quotation

After collecting the above information, we can calculate the configuration of the solar energy system. For example, we finally confirmed the 60W (150lm/w) LED lamp, 150W solar panel, 100AH ​​24V battery, and then we can contact the company to request a quote. Of course, if you only have the relevant information of the road, but are not clear about the lighting requirements and solar energy configuration requirements, you can also contact a professional supplier to obtain the configuration of the solar energy system. After you get quotes from different suppliers, be sure to research the company and the product. The quotation needs to specify the lamp wattage, luminous flux (Watts to lumens/luminous flux), charging and discharging method, solar panel wattage and battery capacity. If conditions permit, ask the supplier for a lighting simulation to ensure that the solution meets the corresponding lighting standards. In addition, the battery capacity must be calculated to confirm that the battery can provide 0.5-2 days of backup. Finally, we need to remember that the lowest quote is not always the best. Either the wattage is false, the battery capacity is false, or the battery used in the product is not of high quality, etc. You often weigh the product information of each company and then make the best choice for the project.

ZGSM solar street lighting solution

ZGSM received an inquiry from Panama, which required lighting an urban expressway. This is because the original lamps could no longer meet the lighting requirements. The road is a two-way 4-lane road (7 meters in one direction), with an isolation island (0.6 meters) in the middle, the distance between lamp poles is about 30 meters, and the design speed of the road is 80km/h. The customer required the lighting design to be carried out according to M2, and ZGSM finally confirmed that the wattage of the lamp is 45W, 220lm/W. If the lighting class is unclear, we need to know more about the road conditions to help us confirm the lighting class. The following is the result of the lighting simulation, we can see that the luminance = 1.52cd/m2, uniformity (What’s the uniformity?) U0 = 0.59, UI = 0.82, glare Ti = 6, which meets the requirements of the M2 lighting class for the three indicators.

Then, we can proceed to the next step of calculation. We learned from the customer that the road was initially designed with electricity access, so there was no need to consider the situation of insufficient power due to rainy days. At the same time, the customer wanted the light to be with timer dimming (What’s timer dimming?) and hoped that the power would be 100% in the first 4 hours, 30% in the next 5 hours, and 70% in the last 3 hours. Finally, ZGSM was designed with a 1.3 times margin, and the panel was confirmed to be 110Wp and the battery capacity was [email protected]. Considering the high wiring requirements and high installation costs of the split solar street lights, we recommended that the customer use an integrated solar street light, and finally confirmed the ZGSM-PV5-45 all in one solar LED street lighting solution. If you are interested in calculating the capacity of solar panels and batteries, you can refer to our blog – Important parameters and calculations of solar street lighting systems. In addition, if you are interested in solar street lights, whether they are integrated(All in one), all in two or split solar LED street lights, you can click on the picture below to get more product details.

Summary

Solar LED street lights are an alternative to traditional electric street lights. Solar street lights do not require a power grid because they are self-sufficient units that generate electricity from batteries during the day and supply it to LEDs at night. LED street light fixtures provide better lighting solutions with lower system configurations by using lower power, better optics, and dimming functions on demand. It is the unique advantages of solar energy and LED street lights that make solar LED street lights the current mainstream. Through the text, we also know that when confirming the system configuration, we should pay more attention to lumens (watts to lumens), and then confirm parameters such as panels and batteries based on this. Through this method, combined with the lighting simulation provided by the supplier, it is effective to avoid purchasing solar LED street lights with false lumens or watts. In addition, when making configuration selections, factors such as timer dimming, microwave sesnor (More about street light with motion sensor), and mains access also have an important impact on the system configuration. Users need to consider these factors comprehensively to choose the solar LED street light solution that best suits their needs. For further information, please contact ZGSM for more relevant information and products.

Related Products

Related Blogs

Related Cases

People also ask

Author introduction