Buyers Guide to Street Lighting

LEDs Make Streets Brighter

Street lights have a very obvious purpose that is lighting up the walkways, driveways, and other similar areas to ensure a safe driving and walking experience for the passersby.

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The main aim of streetlights is to make all the objects under them clearly visible so that any potential obstructions or hazards can be easily identified and avoided. Several studies have shown street lights cause around a 40% reduction in car accidents.

Street lights must be installed to save passengers on any street safer against accidents and further damage. You may think that higher brightness is all that is important for street lights but that is not true entirely.

Brighter lights increase the risk of shadow spots that become blinding for drivers. This is one of the many important factors that need to be considered while picking the perfect street lights. We are going to do a quick rundown on such factors below:

• The light output of the bulbs
• Reflection value of the particular target surface
• Ability to render colors
• S/P ratio of light and mesopic vision
• The ratio of maximum lumens, average lumens, and minimum lenses
• Uniformity of light distribution
• Fixture angle cut off
• Mounting pole height: The perfect lighting density can be achieved with optimum pole height. This is because light density starts decreasing with the increase in the height of the mounting pole.

The brightness of roadways or street lights denotes their total light output. You may have come across many streets and roadways lighted by the metal halide lamps.

These lights come with a lot of challenges that we will mention later but the most problematic one is the harsh glare they cause to the head-on onlookers. So, what can be done to avoid this? The answer is LED lights.

Brightness of the Street Lights

The Angle Made by Light Above the Nadir

The Term Nadir is Used in the Lighting World and it Denotes the Angle That Exists in the Downward Direction from the Center of Any Light Spot. This Point Lies Perpendicular to the Surface.

The IES or Illuminating Engineering Society is a non-profit organization responsible for curating lighting standards. It uses nadir for qualifying street lights as non-cut off, semi-cut off, or full cut off.

We have included a table below that shows the relation between light level percentages and luminaries classification.

Fixture Classification % Total light output at 90° from Nadir Percent of Total Candlepower at 80° from Nadir Full Cutoff 0% <= 10% Cutoff <= 2.5% <= 10% Semi Cutoff <= 5% <= 20% Non Cutoff No limitation No limitation

The full cut-off lights can be seen as being the downward-pointing light sources. This is crucial for Dark Sky regulations (mentioned later) as it causes the minimization of unnecessary light dispersion towards the sky. An added benefit is that they allow the usage of lower-wattage lights because light wastage is a rare case here.

You can make the light sources more focused and directional by equipping them with a light shield simply. A light shield boosts their brightness even with lesser lumen capacity and decreases harsh light production. In place of all this, you can simply use LEDs that are built to provide directional light. They promote improved optic quality and lifted light angles for great outdoor lighting.

The IES or Illuminating Engineering Society has recently become more vocal about the importance of BUG ratings for street lights.

The BUG rating system is highly comprehensive at rating the lights on three unique standards- glare, up-light, and backlight. However, we will be discussing the previous classification only since it is still being used by the municipalities.

What Makes the Full Cut-off Lights So Crucial?

To help save energy and minimize light pollution in the environment is the main aim of full cut-off lights. This is closely related to Dark Sky complimenting.

The concept involves the making of skies &#;night friendly&#; to make heavenly bodies clearly observable to astronomers and minimization of anthropogenic lighting effect on the circadian rhythm of nocturnal earthly bodies and all this is achieved by freeing of skies from ambient light levels.

The basic idea is to reduce the contribution of light fixtures towards environmental light pollution. These regulations are strictest in coastal areas but must be practiced elsewhere too.

Various Luminaries and Their Light Footprint

The figure above describes the most popular luminaries&#; varieties and their distinctive installation spots on the roads as per the IES standards. This depicts the distinctive working processes of luminaries in various situations.

Type 5 lights work better for installations to achieve a 360-degree brightness footprint in places like roundabouts or 4-way stops and type 1 lights work better for achieving better light footprints on areas like road medians.

The Major Hurdle in Calculating the Light Output of Fixtures in Lumens

The basic presumptions on which the calculation method of lumen output rests are equitable light quality and absence of light reflection. Theoretically speaking, the amount of light reflection varies according to the color of the particular surface and this also affects the brightness levels generated.

For instance, if yellow light is falling on an object of green color, the light will get absorbed and cause the object to appear black rather than its original color.

However, the reality is that greener objects, like leaves, are replete with multiple pigmented substances like xanthophylls, carotenoids, chlorophyll, and others that cause some reflection of the yellow light and appear grayish as a result. This makes higher luminosity output important from the roadways LPS fixtures.

LPS fixtures generate single-colored light in the whole spectrum. At the same time, LEDs generate a full light spectrum. This causes higher contrasting and highlighting of the color differences in target objects even with lesser lumens and the onlookers&#; experience improves optic power and securer feeling.

Another factor that makes the color perception of objects better is the CRI or Color Rendering Index. Read here to know about CRI in greater detail but you must know that CRI is a measurement scale of light quality. CRI makes lights brighter with lesser lumens and this directly impacts the stimulation of rod cells in human eyes.

It is equally important to consider the future developments in lighting that can take place while choosing LED lighting systems. Some such important developments include:

1. Intelligent Lights

These are advanced LEDs fixed with motion sensors that render them the capability to generate various light outputs with no impact on brightness as per the ambient light levels.

Such technologies can be used further to equip the sensors for giving light outputs as per light levels and do all of this within minimized energy consumption according to the levels of natural light outside.

2. Multi-functional Lights

These lights can be used for gathering information on different things like weather and traffic, etc.

3. Solar Panels

Lights can be fixed with solar panels to reduce the risk of environmental light pollution.

The Right Light Dispersion for Street Lights

There are certain arrangements you would need to make while installing the street lights to make them anti-glare and generate evenly distributed light so that the street becomes safer for the passengers. We are talking about the light rays generated beyond 75 degrees from the Nadir that are harmful.

This light is glaring and harmful to drivers. This is why LEDs are a better choice for street lighting as they are anti-glare and produce balanced light. At the same time, HPS fixtures produce much higher glare due to their light rays being angled beyond 150 degrees.

This is the picture of a light setting that has the wide-angled HPS fixtures being used in it. You can notice the high amount of light wastage. The houses near the street have their curtains drawn mostly to save their windows from being unnecessarily lit all the time due to the high light distribution. This further causes light pollution affecting nature experts and astronomers too.

This can be eliminated with the LED lights that give focused and directional lighting. The houses near the streets won&#;t need to hide their windows with curtains like in the case above anymore since the lights won&#;t be reaching anywhere but the target space. This also causes a lesser lumens requirement since the light is being used for the set purpose only.

Uniform Light Dispersion

It is only after the installation of the street light that you can assess the uniformity of light dispersion.

Uniformity comes with a balance between several factors like light optic properties, luminary reflector quality, crossing areas between the bulbs, and others. The following three ratios determine light dispersion uniformity:

• The ratio of average to minimum light intensity
• The ratio of maximum to minimum light intensity
• The ratio of maximum to average light intensity

The first two ratios can be determined easily which makes them more preferable.

Light dispersion uniformity plays a crucial role in glare reduction. Glare decreases the amount of light reaching the eyes by impacting the pupils into shrinking.

Some of the most popular methods of avoiding glare include blinking, squinting, wearing sunglasses to lower the brightness in the whole vision spectrum, and using various devices like peak caps to reduce the brightness part of the visibility spectrum. However, none of these methods come in handy to the nighttime street passengers.

Comparison of High-Pressure Sodium and LED

Municipalities are on their way to transforming the streets with boosted safety measures and changing from HPS to LEDs is one of the major decisions they are taking. Even though the energy-efficiency quotient of LEDs is visibly higher, lot more things need to be considered.

The National Lighting Product Information Program or NLPIP discusses these issues in its publication. Their study was based on eight street light samples belonging to top companies and the following were the observations:

1. The output of LED lights is lower. This can be a deterrent but not a surprise altogether because the labels on the LEDs displayed their lower lumens as compared to the target HPS fixtures.
2. LED lights promote savings. This is completely unsurprising. LEDs need to be installed at closer gaps despite them being highly bright than the HPS fixtures. This led the NLPIP to worry about the energy savings rising due to the extra lights that would need to be installed. However, the final result was that LEDs remained more energy-efficient even with the additional numbers.
3. LED companies prefer fixtures to have lower lumen levels. You need to still have LEDs with suitable lumens to match the HPS fixtures they are replacing even after being spaced similarly.

Overall, you will find out the initial cost to be much higher when carrying out the LED lights conversion. However, even the studies of NLPIP approved that the lifespan and efficiency of LEDs are much higher than the conventional HPS lights. Thus, LEDs are a better option for street lighting for long-term benefits.

What is the Cost of Street Light LED Conversion?

1. The Initial Cost of Items like Electrical Wires, Poles, and Bulbs Plus Installation Cost

On average, it takes around $ for the installation of a single light pole. This cost can vary depending on the pole height, the foundation required, the distance of the pole from the electricity source, light efficiency, and light power ratings.

Usually, in rural areas, electricity sources are placed farther which requires longer wire stretching to give power to the lights. To avoid such a situation, solar-powered lights can be used in such areas but the higher cost is their downside.

2. Cost of energy consumption by the lights

Consider replacing a metal halide bulb without changing the fixture at all with a 100-watt LED Light, this means that the bulb will produce around lumens of higher quality light by consuming 100-watt power.

Calculating this way, around kWh of power is used by the street lights installed in Los Angeles at the rate of 250 watts per hour. To save on this enormous energy consumption is the prime motive behind Los Angeles and another shift to LED lighting systems.

3. Cost of Bulb Disposal and Changing Fused Bulbs

You may have not thought about it earlier but even disposing of and replacing the street lights incurs a charge that is higher too. The average money spent by Los Angeles in controlling and maintaining around street lights is 42 million dollars. This equates to $200 spent per light every year.

The primary reason behind this high cost is pole height because dealing with the lights at such a height requires machines like cherry pickers and trucks to carry the workforce or lift there.

A comparative study was done by U.S. Naval Observatory Flagstaff Station personnel Christian B. Luginbuhl of the various outdoor lighting systems led to him conclusion that LPS fixtures have a lower lifespan than the HPS fixtures by nearly hours and they also need higher maintenance.

This is one crucial reason other than no color rendering capacity that makes Low-Pressure Sodium lights less preferable. At the same time, Metal Halides and HPS have an average lifespan of nearly to hours. Even worse is their lumen depreciation that is L50.

Calculating the Replacement Cost of One Bulb

Cost of the new bulb + Payment of two mechanics + Rent of man lift + Cost of renting a truck = +/-$800 (We have assumed the cost of a single bulb and ballast to be around $150).

The unfortunate case in many cities is that the municipalities have to meet the demands of higher or at least average-quality services in the limited funds that are available. Such situations can be made better with newer lighting technologies.

There are remote control systems that can reduce the physical maintenance cost of street lights. A good example is an LED lighting system that has a higher average lifespan of about ten extra years. The light systems of certain cities like Ann Arbor require higher maintenance which can be dealt with modern lighting technologies.

Are you looking for a solar-energy-based illuminating solution for either your own courtyards or some public sites, such as playgrounds, pathways, parking lots, plazas, etc?

Or, you are upset about the short autonomy of your current solar street lights with traditional technology, which, sometimes, especially during monsoon, have to subsist on the national electricity grid?

(some hybrid solar street lights systems are grid-tied systems, they are designed to connect to the national electricity grid. When their own battery bank runs out of power, they will switch to the electricity grid.)

However, things can be worse.

Your projects could be located in some remote rural areas or isolated islands, where no electricity can reach. How can your solar-powered street lights survive a spell of raining weather?

You may say we should increase the size of both battery bank and solar panels. Well, this sounds plausible in engineering respect, but when it comes to the project budget, this also means the raising of outlay significantly since the cost of battery accounts for a larger part.

Then, why not adopt the ones with advanced technology, all in one solar street lights.

Without further ado, let&#;s dive right in:

Chapter 1. What is all in one solar street lights?

All in one solar street lights are one type of integrated solar street lights, which

integrates into a product the four main components: solar panel, light source, battery, solar energy cables, and solar controller.

Now let&#;s go through the details of each module one by one

The major modules

# Monocrystalline Solar Panel

Monocrystalline and polycrystalline solar panels are two different solar panels which are widely applied in the solar industry.

Generally speaking, monocrystalline performs better than polycrystalline, especially in cold weather they have higher energy conversion rates than polycrystalline. To data, Sunpower monocrystalline solar panel can reach as much as 24.1% conversion rates.

So, Monocrystalline panels are installed in all in one solar street lights due to its limited size.

These solar panels act as the role of energy collecting and conversion, in the daytime, they collect energy from the sun and then convert them into electric power which will be stored in batteries as chemical energy.

# LED Light source

Suffice it to say, as light sources LEDs are prevailing among illuminating market, for its high performance in energy-saving. It definitely can be counted as a new generation of lighting solution.

LED types vary in size and watts, such as , , , , to adapt to different applications.

Our S2 series integrated solar street lights is with Philips LUXEON SMD, which has almost 190 lumens per watt. A LED module is formed by these single SMDs which are soldered to an aluminum substrate in advance.

Furthermore, an aluminum heatsink is always applied to the rear side of the led modules to help dissipate the heat generated by LEDs. This is very important, for although manufacturers claim that LED has a lifespan of more than 50,000 hours, its light depreciation can be abnormally high if it is working in a temperature larger than 70 Celsius. So we must make sure that the LED junction temperature is under 70 Celsius.

# Lithium-ion Battery

Rather than car batteries, which are designed to discharge a large amount of energy in a short period of time, renewable energy industries prefer deep-cycle batteries, for their excellent characteristics in the enduring power supply, deep discharges and far more cycle times, times, twice or three times more than that of car batteries.

Batteries cycle times is also affected by the depth of discharge(DoD), we will talk more in Chapter 5.

There are two main types of deep-cycle batteries existed in the solar battery market: lead acid and lithium.

Why do all in one solar street lights use lithium-ion battery?

5 reasons:

1. Flooded lead-acid batteries require maintenance, say, equalization
2. Although sealed lead acid batteries are maintenance free, they are pretty expensive than flooded ones
3. Both two types of lead-acid batteries occupy too much space to be set up in all in one solar street lights, which is compact design and with small spaces inside.
4. Lithium batteries have longer lifespan than lead-acid batteries, six times the number of cycles compared to a lead-acid
5. Lithium is capable of surviving irregular discharging and maintenance free.

However, manufacturers often use two types of lithium-ion battery

• ternary lithium battery,
• lithium iron phosphate (LiFePO4) battery,

Difference between them?

What kind of lithium-ion battery should I use in my projects?

What we have learned, from the comparison table above, is that LiFePO4 battery is more expensive, but its chemical substance inside is more stable, which makes it kind of high-temperature resistance, while ternary lithium battery is relatively low-temperature resistance, for its materials are more active and can work under 0 Celsius.

So, if your project is in the tropics, LiFePO4 battery is recommended. But if the project is in northern countries, we advise ternary lithium battery.

# MPPT Solar Charge Controller

There are 2 types of controller: PWM and MPPT in the market.

All in one solar led street lights adopts MPPT, for, in this case, PWM will waste some energy collected by panels, while MPPT can convert all the solar energy collected into chemical energy

As the main functional component, MPPT solar charge controllers have some basic functions as below

1. Dusk to dawn control

The controller is always monitoring the voltage of the solar panel, which increases or decreases with the intensity of the sunlight. When it is lower than 5v, towards dusk, the control will switch on the LED lights. And when it is towards daybreak and the voltage is larger than 5v, the LED lights will be turned off.

2. Time control

The solar controller can also control the power output according to the time schedule, for instance, you want

• 70 percent brightness from 6:00 pm to 7:00 pm,
• 100 percent from 8:00pm to 10:00pm,
• 30 percent from 11:00 pm to 5:00 am.

Commonly, a controller has around 5 time-slots you can use to set according to different requirements of projects.

Time control is often used in conjunction with motion sensor control. For example, from 11:00 pm to 5:00 am, there are few people on the road, so you can set only 30% power during this period, meanwhile, only capitalizing on the motion sensor to raise power to 100% when a passer-by is detected.

By doing this, we can save a lot of energy to boost the duration of off-grid solar street lights and ramp up the days of autonomy.

3. Motion sensor control

A controller can take action when it receives a signal from the motion sensor to increase LED brightness when someone is in sensor area, and then revert to the former level of brightness when it moves out of the area.

4. Preventing overcharge and Low voltage disconnect(LVD)

Either overcharge or over discharge can dramatically reduce the lifespan of batteries, although batteries modules themselves have this sort of protection, solar charge controllers usually have the same function analogous to that of battery modules. But be rest assured, the two are not conflicting with each other, for they function in different dimensions.

# Infrared(PIR) Motion sensor

Infrared and microwave motion sensor are two popular types in all in one integrated solar street lights, the infrared motion sensor detects heat source movement, while microwave ones send microwave radar and receive the bounced signals to analyze the changes in bounced signals.

Our all in one solar street lights incorporate infrared types, which have a 120-degree working angle and can detect a squat cone space under the lights.

We do not prefer microwave ones, although they have a larger working angle, they are rather too sensitive and more likely to respond to some wrong movements, such as swaying trees, fluttering birds and flapping flags. Those wrong response could consume lots of gratuitous battery energy, and that&#;s what we do not expect.

Above is the introduction of the primary components.

However, as integrated solar street lights, all in one solar street lights can also integrate some other functioning modules, such as Bluetooth, CCTV(Closed Circuit TV), or even wireless monitoring system, which enables end-users to monitor the status of each lights or even to control every lights by PC or mobile at any places where there are internet services.

Then, How do all these modules work as a complete system?

We will talk about the working process in 2 aspects:

Chapter 2. How does an all in one solar street light work?

#Charging

First, the solar charge controller will turn off LED lights towards dawn once solar panel voltage rise to 5v, which is accounted for a little sunlight in the morning.

When there is enough sunshine during the day, the solar panel will work together with the solar charge controller to collect the solar energy.

Commonly, in a 12v solar system, with the effect of insolation, the voltage of its solar panel will rise to around 18v so as to charge the 12v battery bank. Meanwhile, the solar charge controller will prevent overcharge to protect the batteries.

#Discharging

When there is not enough sunlight towards dusk and solar panel voltage drops to a value under 5v, the LEDs will be turned on accordingly.

&#;Time control mode&#; and &#;Motion sensor control mode&#; will be working during discharging at night.

As primary function, Time control is used to customize different brightness in different time slots. For example:

• Time slot 1: 6:00 pm &#; 7:00 pm, 50% brightness
• Time slot 2: 7:00 pm &#; 8:00 pm, 70% brightness
• Time slot 3: 8:00 pm &#; 10:00 pm, 100% brightness
• Time slot 4: 11:00 pm &#; 2:00 am, 50% brightness
• Time slot 5: 3:00 am &#; 5:00 am, 30% brightness

And so on.

a motion sensor is used as a minor function which can be recognized as an energy-saving mode

The LEDs&#; brightness will rise to 100% when someone is approaching the lights and then revert to the previous level of brightness 20 seconds after the man leaves.

Chapter 3. Why should we use all in one solar street lights?

Why traditional solar street lights were not that popular?

In the past, why people do not tend to choose solar-powered street lights is due to three major reasons,

1. Lighting bulbs are energy consuming

Both MH(metal halide) and HPS (high-pressure sodium), which were used as light source in streetlights at that time, are with the relatively obsolete lighting technology (60-80 lumens/w) compared with that of the LED. those bulbs/lamps usually require a large amount of energy per day from its battery bank, which is considered as a downright burden to its battery capacity.

2. The LED technology is newly-developed and pretty expensive

In those days, although LEDs had been on the market in commercial outdoor lighting for a few years, the technology was still not mature. Their lighting efficiency was only 100 lumens/watt (now, in , it can be up to 200 lumens/watt). Furthermore, since LEDs were newly-developed at that time, the cost was rather expensive and the average man on the street could not afford to buy.

3. Lithium-ion battery technology is not well developed

The third reason is the solar battery. The lithium-ion battery has the longest lifespan as one kind of deep cycle batteries, but they were not stable and would fail to work under 0 Celsius. (now, the working temperature of ternary lithium battery: -30 to 65 Celsius)

However, Things have changed over years.

New technologies are applied to solar street lights?

The size of both batteries and lighting sources is increasingly small nowadays.

Qianyun Product Page

Thanks for the technological breakthrough in both the lithium-ion battery and LED lighting. These developments make it possible for the solar lighting industry to develop integrated solar street lights.

1. Battery

Compared with lead acid batteries, lithium batteries are lighter, smaller, with longer lifespan and larger DoD, what is more important is that lithium batteries are with larger capacity at the same volume.

2. Light source

Compared with MH/HPS bulbs, LED takes up far less space in the lamps

What can we benefit from the latest technology?

1. No wiring, and easy to install within a few minutes

there is no complex wiring process, even if you are the end-users, you do not have to be with an engineering background or skills of setting electrical equipment, all you need to do is fixing the product with 12 pieces of fastening screws. Your family will stand to benefit from the free solar energy all the time.

2. 60% less energy consumption, which also means more days of autonomy

The light sources of most conventional solar street lights were Metal Halide(MH) or High-Pressure Sodium(HPS), which luminous efficacy is only 60-80 lumens per watt. However, nowadays, the cutting-edge LED lighting technology has dramatically boosted it up to about 200 lumens per watt. People can get the same brightness at night by consuming much less energy from solar batteries.

All in one solar street lights with this kind of light source easily realize 5+ days autonomy, making it possible to work normally in places with rainy seasons or less insolation.

3. Better hurricane/typhoon resistance ability

All in one integrated solar street lights are designed with compact structure, compared with that of split-types, which solar panel are separated from the lamp. This kind of structure has better performance in withstanding hurricane/typhoon.

Split-type solar street light will not withstand such inclement weather since its separated solar panels are more likely to be shredded by storms.

4. Lower transportation cost benefits from compact structure and all-in-one design

If you are a businessman, compact design means a lot to your profit margin.

The whole container loads of solar street lights could be twice or even three times more than before, in the meantime, the rent of the warehouse can cost much less than before.

Besides, due to the convenience of installation, which we talked in #1, your company will save even more local labor costs.

And more&#;

Chapter 4. All in one solar street lights VS. Traditional solar street lights

In this chapter, we will go through a concrete example by presenting a comparison table between them, so you can figure out the pros and cons more easily.

the same brightness, working hours, and days of autonomy,

But it is obvious, the upfront cost of all in one solar led street lights is fairly low,

it only needs 27Ah battery and 50 watts solar panel, whereas traditional solar street lights require 156 Ah and 280 watts, let alone other extra wiring costs that are entailed in installation.

Chapter 5. How to get a qualified all in one solar street lights?

needless to say, the quality of products is very important to businesses, sometimes, is crucial for winning tenders.

But can you always get a qualified all in one solar street light? I doubt it.

You might encounter problems:

• even if you have been in this business for years, but you still have no idea about what exactly standards for an eligible product?
• you might have learned the standards, but how to achieve? What factors affect the quality?

Let&#;s dive in the content with these questions you may have.

For almost all kinds of integrated solar street lights,  QC mainly focuses on the following items:

• CCT & CRI
• LM80 standard
• Battery cycle times
• 3 transportation testing for lithium batteries
• Ingress Protection standard
• Working temperature

Let&#;s review each one in detail.

CCT & CRI

CCT & CRI are important optical factors for illuminating

CCT stands for correlated color temperature.  lower value tends to yellow, while larger value tends to white and even with a little blueish color, refer to K in the picture.

K looks like the sunlight at dusk or daybreak, the sunlight at noon is around K, K is called natural white, compact fluorescent lamp commonly has -K.

Nowadays, nature white(-K) is always using in solar street lights.

Color rendering index (CRI) indicates how well a light source allows the substance to reflect its real color, the higher the CRI, the more an object can reflect its real color under this light source. Refer to the CRI 80 VS CRI 90

However, larger CRI also means more brightness loss as compensation. Namely, when we use the same chips to produce LED, if we make it with higher CRI, its brightness will be relatively dimmer than the one with lower CRI, so we commonly apply CRI 70 to the solar street light industry to get somewhat equilibrium.

Method

With the help of the integrating sphere, we can easily get the two optical parameters when inspecting the incoming raw materials. In fact, integrating sphere can also help to get even more electrical parameters, such as illuminance(brightness), lighting efficacy and so on.

LM80 Standard

LM80 is related to the lumen maintenance of LED, this standard requires the LED to meet the following table

Since human eyes will not perceive the depreciation until it drops to 30%, an LM80 certified LED can definitely walk you through 50, 000 hours without becoming dim sensorily

Method

Some types of equipment are specially designed to do this test accordingly, although it is very expensive.

If you do not want to invest such huge and expensive facilities, our advice is to complete the job in a third party laboratory with little payment.

Battery cycle time

Battery seems to be the most vulnerable part, they have the higher failure rates than the others, its lifespan depends on not only the materials and workmanship but also how we use it, for examples, how many proportions of power is discharged before next charging, specifically, the depth of discharge (DoD)

In solar street lights systems, the larger proportion the batteries are discharged every day, the shorter its cycle times will be.

Batteries manufacturers declare the cycle times of their lithium battery to be &#; times, which is based on the scenario that the battery is almost fully discharged each time.

However, we need to verify this data by ourselves so as to be responsible for the quality

Method

Use an instrument like this one can help to record the testing data automatically, some of them have UPS(Uninterrupted Power Supply) function to guarantee a complete testing process and the data integrity.

UN38.3 transportation testing for lithium batteries

UN38.3 is for the safety of transportation of batteries or products with batteries, it includes 8 test items

1. Altitude Simulation
2. Thermal Test
3. Vibration
4. Shock
5. External Short Circuit
6. Impact
7. Overcharge
8. Forced Discharge

Over those procedures, UN38.8 requires there is no leakage, no venting, no disassembly, no rupture, and no fire.

These are more extreme test conditions compared with normal working conditions, products which have passed UN38.3 are definitely able to perform better.

Ingress Protection standard

All in one integrated solar street lights are outdoor lighting, so they have to withstand a hostile environment where they may fail to work because of dust or rainfall.

Ingress Protection(IP) rating is used to define the grades of resistance against dust and water.

Outdoor lighting fixtures are usually with an IP65 rating, which is the highest protection level for outdoor luminaire except for underwater luminaire. The first digit 6 is for dust and the second digit 5 is for water.

Though there is waterproof seals set between the enclosure over the final assembly, those interior components themselves are watertight too. For instance, the wiring connectors are all waterproof, and the controller is IP67 rating.

Method

Apparently, referring to the picture above, a mimic raining environment is necessary for final testing, and it is more useful during the stage of design or pilot production.

If you do not have a spacious site for this kind of voluminous facility, we also suggest seeking a third party laboratory to help you with this work.

Working temperature

Outdoor temperature varies with location or season, the working temperature will directly affect the performance of each component or even lifespan in some extreme situations.

So either respective modules or assembled products needs testing and monitoring.

Engineering and QC take in charge of these jobs in a factory, when:

• new product design,
• pilot production,
• raw material changes,

As with others, these processes also rely on special tools.

Method

The equipment is used to imitate various working environments to test the tolerance of electronic products. The technician can also set worse working temperature than a real condition to check whether the electronic modules could survive from the testing.

Chapter 6. All in one solar street lights applications

The regions with sufficient sunshine is a must for a solar-powered facility to work normally.  The same principle applies to all in one solar street lights. Furthermore, as an off-grid solar-powered product, all in one integrated solar street lights can be used in remote areas where there is devoid of the infrastructure of the power station, such as islands, famous mountains surmounted by beauty spots, or some countryside.

However, as lighting products, all in one integrated solar street lights are mainly installed in the outdoor sites where illumination is required at night.

These sites are generally classified into four different areas as below:

1. Roadways

Fixtures: roadway lighting, street lighting

Locations: highway, road, motorway, lane,

Roadways represent a variety of ways for vehicle traffic. These ways require narrow beam angle across the road and wide beam angle along the road, for this can increase pole spacings and reduce the numbers of streetlights on it.

Recommend light distribution types:

Type II, Type III

2. Open Areas

Fixtures: parking lot lighting, park lighting, playground lighting, airport lighting, outdoor security lighting(sometimes with cameras)

Locations: airport, park, garden, parking lot, playground, tennis court, outdoor basketball court, intersections

Open Areas often connect vehicle traffic to pedestrian traffic, including the locations with public activities, such as the park, garden, and the places where security monitoring is always processing, such as parking lot, intersections.

these areas need illumination solution at night for either human activities or the scrutiny of the safety and security.

Recommend light distribution types:

Type II, Type III, Type V,

3. Pedestrian Areas

Fixtures: pathway lighting

Locations: plazas, courtyards, and pathways

Pedestrian areas indicate the transition between the building and its surrounding sites since these transition areas cover irregularly shaped spaces, more lighting distribution types may require for this kind of projects.

Recommend light distribution types:

Type II, Type III, Type IV, Type V,

4. Site Perimeter

Fixtures: Perimeter lighting, site lighting,

Locations: factory perimeter, industrial zone perimeter

Some sites, for instance, your villa, require illumination around its perimeter and exclude illumination onto the site itself, for at night you do not expect the street light trespass on your private space, especially bedroom.

Recommend light distribution types:

Type II, Type III, Type IV,

In the MH/HPS ages, this kind of lighting bulbs have to rely on reflector cup to shape special light distribution types on the ground, those cups usually installed above the bulbs, this is another reason why old street lights are too big to be integrated.

Whereas in LED ages, engineers only need to have a thin lens installed onto the LED to realize various light distribution types.

Chapter 7. how to design a project with all in one solar street lights(Case study)

Here is a real-life inquiry from Oman.

Since there is lack of detailed information for designing a project, so we ask for more information, and the customer sends them in attachments

We spent some time to study and organize the information from the emails

At last, the customer&#;s requirements are listed below

1. 100w rated wattage, all in one solar led street lights for a roadway project
2. The road is 12-meter width
3. Mounting height 10 meters
4. minimum required illumination level at the ground: 5 lux
5. 12 hours/day, full power operation
6. 5 days of autonomy
7. materials are suitable for continuous 55 Celsius (the testing method is in Chapter 5)
8. IP65 waterproof.

The engineering process started firstly from checking the existed IES files to guarantee the 5 lux optical requirement on the ground

let&#;s go through the steps one by one

Step 1: check IES datasheet

Our 100w happens to be tested at the mounting height 10 m ( MH = 10 m), and it central illuminance can reach around 8 lux,

(tips: if the mounting height is 7 meters in your project, you need to multiply factor 2.041 in the right column to get relevant lux data on the ground)

Step 2: adjust the distance between the poles

In the course of simulation of engineering, IES files and Dialux can help engineers to get appropriate pole distance pretty easily.

process?

1. load the 100w IES file into software Dialux
2. Set the pole position: both sides or only one side?. (in this case, only one side installation is allowed)
3. Input basic parameters: road width, mounting height, preliminary pole distance, and the number of lamps per pole.
4. Try a different value of pole distance on the basis of using minimum streetlights, until you get &#;minimum 5 lux on the ground&#;

In the end, we decide 25 meters is the best pole distance. And at this time, the minimum illuminance is about 7 lux.

Step 3. Calculate the battery size

So far, optical parameters and installation positions have all been determined.

Next, we need to size the solar battery according to requirements, 12 hours/day and 5 days backup

1. The LED modules in this 100w model require working current 1.34A.
2. 12 hours full power operation consumes battery power 1.34A x 12H = 16.08AH
3. for 5 days backup, we need (16.08AH x 5 = 80.4 AH)
4. So we select an existed battery size: 84AH for this model.

Step 4. Calculate the solar panel size

The final step is to size the solar panel according to battery size 84AH and the peak sun hours

1. The solar irradiance in Sultanate of Oman is sufficient, its peak sun hours is about 6.5 hours
2. 84AH / 6.5 = 12.92 A, so we need 12.92A current from solar panel for 6.5 hours
3. For LifePO4 lithium battery, the charging voltage is 18v
4. 18V x 12.92A = 232.62 W, that means we need about 230 w energy from solar panel per day theoretically
5.  Since the battery is not always totally empty, so we usually multiply a coefficient, 0.7
6. 232.62 W x 0.7 = 162.84 W

Our 100w model is equipped with a 170w monocrystalline solar panel.

So, finally, we prepare the products with recommended parameters as below

• 170W monocrystalline solar panel
• 84AH LifePO4 lithium battery
• 100w rated LED model
• 10 000 lumen
• IP65

Conclusion

All in one solar street lights is a new trendy type of solar street lights, And this trend will be strengthened as the development of sodium-ion batteries, which is even powerful than current lithium-ion batteries.

Although it may take some time for sodium-ion batteries to go out from the laboratory to real-world applications, it is worth expecting. And at that time, solar street lights will be powerful enough to replace all streetlights.

Interested in estimating your potential projects with the help of our experts?

Or,

plan to replace traditional solar street lights with our all in one integrated solar street lights?

Or,

you do not want to miss out on the benefits to illuminate your own factory zone, and even courtyards or backyards?

For more information, please visit automatic street lighting system.