When we buy quality solar streetlights, we must not just look at the specifications advertised by the suppliers. Because the battery that the supplier may advertise is 100Ah, but the actual product purchased is only 10Ah. Even with the same capacity, the available capacity of batteries of different grades is different. For the same solar street light, some suppliers label 60W, and some may label 300W.

People want to buy the cheapest products, but the cheap ones do not mean the most cost-effective. It also depends on the effect and longevity. For example:

• With the 10 years lifespan of a $300 high-quality solar light, the average annual cost is $30.
• With the 1-year lifespan of a $100 poor-quality solar light, the average annual cost is $100. If it is broken, it is a waste of time and energy cost, which is actually not worth it.

• The charging and discharging environment temperature of the LiFePO4 lithium battery is up to 65 degrees Celsius.
• The charging and discharging environment temperature of the Ternary li-ion lithium battery is up to 50 degrees Celsius.
• The maximum temperature of solar panels in summer can reach 90 degrees Celsius.

Therefore, if you are in a hot area, such as :

• Africa: Algeria, South Africa, Angola, Morocco, Rwanda, Liberia, Ghana, Mauritius, Equatorial Guinea, Botswana, Gabon, Namibia, Tunisia, Cameroon, Nigeria
• Middle East: Saudi Arabia, Kuwait, UAE, Oman, Qatar
• Southeast Asia: Malaysia, Philippines
• South America: Chile Mexico

You can only use LiFePO4 lithium batteries. Ternary batteries are easy to catch fire. And the heat dissipation performance of the lamp must be good, and the solar panel should not be in direct contact with the battery.If you are at a latitude greater than 15 degrees, the sun will have an inclination angle greater than 15 degrees with the ground. Try to consider solar street lights with adjustable solar panel angles. Solar streetlights installed on both sides of the road should not have solar panels facing away from the situation of sunlight.

Every time the PN junction temperature of the LED chip increases by 10 degrees, the life span of the semiconductor device will decrease by multiples. It can be said that heat dissipation is an important guarantee for ensuring the life and quality of LED street lights. In this regard, bad manufacturers mainly use cutting corners to reduce costs, and this hazard cannot be found at the beginning of use, and it usually takes a period to find out.

The increase in temperature has an impact on the calendar life and cycle life of lithium batteries. The effect of temperature on the life of lithium batteries conforms to the Arrhenius equation. The temperature of lithium batteries increases, and the reaction speed increases. Related research shows that the temperature of lithium batteries per liter at a temperature of 10°C, the degradation rate doubles. When the remaining capacity is 90% of the same battery cell, the output capacity at 25°C is 300kWh, while the output capacity at 35°C is only 163kWh. When the temperature rises by 10°C, the cycle life of the battery cell is reduced by nearly 50%.

It can be seen that temperature has a significant influence on the cycle life of lithium batteries. Therefore, in the process of battery use, it is necessary to avoid long-term use of the battery under high-temperature conditions, especially the high-rate charge-discharge cycle of lithium batteries under high-temperature conditions, in which is also the main reason why the battery must be temperature controlled.

Therefore, the heat dissipation performance of the lamp must be considered. The solar panel is scorching when exposed to the sun. The solar panel must not be next to the battery and the LED light source.

The solar panel of the normal all-in-one/integrated solar street light is next to the battery, and it is a sealed space. The internal temperature can reach 70 degrees Celsius, which greatly damages the lifespan of the battery and the lamp beads. So, we recommend all-in-two or split-type solar street lights.

For using AIO-integrated solar street light in a high-temperature area, Lumentek has the following solutions: 

1. using thermal switch into charging system, when temp. is over 55 ℃, the switch will disconnect to cut off charging from the solar panel to the battery, and will re-connect automatically when the temperature is below 55℃.
2. using heat insulation material to pack the battery pack, to guarantee inner temp. is less than the outside environment temperature in hot summer to protect the battery
3. Using high-temperature battery cell.

Because the solar panel is mounted onto the lighting fixture, all-in-one systems are not very flexible when it comes to directional angles.

Lumentek uses a rotatable and adjustable led module in order to solve this problem

The actual capacity of the battery
Some parameter table Ah look very big, but we buy Wh instead of Ah.
Wh=Ah*V, we can’t just look at the capacity of Ah, but also the voltage. E.g:

• 90Ah, 3.2V actual battery capacity is 90Ah*3.2V=288Wh.
• 30Ah, 12.8V actual battery capacity is 30Ah*12.8V=384Wh

Available battery capacity
A deep charge and discharge will consume the battery's capacity, so to protect the battery, the battery power is generally not reduced to the minimum. Different quality batteries have different pre-stored power ratios, for example, Lead-acid batteries must reserve 50% of the power, so the depth of discharge is 50% of the actual capacity.

The ternary battery must have 30% of the power, so the depth of discharge is 70% of the actual capacity LiFePO4 Lithium battery only needs to reserve 1% of power, so the depth of discharge can reach 99% of the actual capacity.

It can be seen that, in order to achieve the same available capacity, the ternary li-ion battery configuration must be higher than that of the LiFePO4 lithium battery.

What is A grade or Class A battery cell?
The battery factory arranges production according to the production capacity and technical capacity of the factory. After a series of battery manufacturing processes, the final product is delivered to the customer; After mass production of battery cells with the same specifications, it is necessary to measure the cells' rated capacity and internal resistance through a series of testing procedures. If the rated capacity of the cell reaches A predetermined value, the internal resistance is lower than the specified value, and the appearance, performance, and other qualified cell is called Grade A cell.

What is a B grade or Class B battery cell?
Any factory producing products must have a defect rate. Then this defect rate determines the vitality of a factory. There will not be a big gap between the first-line lithium battery and the third-line lithium battery factory in the lithium industry, purely technology, ingredients, etc. Still, the gap between the defect rate is enormous; the first-tier manufacturers can achieve about 2%. In comparison, the second and third-tier manufacturers are likely to achieve 5-10%. It is precise because of this defect rate that grade B cell is created. The grade B battery in rated capacity, internal resistance, appearance, or performance, and the Grade A cell has a certain gap.

Class A LiFePO4 Lithium Battery

• 2000 charge and discharge cycles
• 10-15 years lifespan
• Good high-temperature stability
• Depth of discharge up to 99%

Class B LiFePO4 Lithium Battery

• 1200-1500 charge and discharge cycles
• 5-6 years lifespan
• Good high-temperature stability
• Depth of discharge up to 99%

Class C Ternary li-ion lithium battery

• 800 charge and discharge cycles
• 3-4 years lifespan
• Easy to catch fire at high temperature
• Depth of discharge up to 70%

Class D Disassemble lithium battery

• 300 charge and discharge cycles
• Less than one year lifespan
• Unstable
• Capacity decay Fast

Lumentek uses A-Class LiFePO4 lithium batteries.

The solar panel is not only depends on the size but also its conversion efficiency.
Generally, the conversion efficiency of polycrystalline silicon solar panels is 12%, and the conversion efficiency of monocrystalline silicon solar panels is 15%-24%. The manufacturing cost of monocrystalline solar panels is higher than that of polycrystalline solar panels.

• Conversion efficiency>21% Life span 25 years
• Decay rate after 10 years: 10%
• High-strength tempered glass, anti-freezing, anti-sandstorm

• Conversion efficiency > 16%-17% Lifespan of 15 years
• Decay rate after ten years: 80%
• Low-strength tempered glass
• In dusty areas with high humidity that can create dew on the surface of solar modules, dust can adhere to wetness. This is a general problem in the Middle East and African countries.

In desert regions, such as the Arabian Peninsula, flat PV panels must be cleaned 2 times per month as well as after a sand storm. Despite low labor costs in these regions, this causes significant maintenance costs. Moreover, parking trucks for cleaning on street are a safety risk and can cause congestion.

We have the following solutions for our solar street lighting system in dusty and snowy Areas:

• Using Cylindric solar panels
• Coating self-cleaning Nanocoating on the solar module, stops dust and bird poo from sticking to PV panels. With the help of the coating, all dirt will be easily removed after a little bit of rain or after manually spraying water on the panels.

The cylindrically shaped solar panels have the following advantages comparing flat photovoltaic panels:

• Reduce dirt deposits. Reduce maintenance costs.
• Reduce wind loads and pole costs.
• Pretty design.

Sensors are divided into microwave induction and infrared induction. Microwave induction can sense moving objects, and infrared induction can only detect temperature-bearing organisms.

Microwave Sensor

• Sensing distance 8-15m
• It affects both people and cars

Infrared sensor

• Sensing distance 5-8m
• Can only sense people

The light source looks dazzling does not mean high illuminance. With the same lumens, if the light-emitting area of the LED light source is smaller, it looks more dazzling, and human eyes will mistakenly think that it is brighter. There is a vertigo index in the street light. The higher the vertigo index of the street light, the less safe when driving.

For the same lumens, the smaller the angle of the lens, the more concentrated the area hitting the ground and the brighter the light, but at the same time, the  overage of the light is smaller.

We should not only look at the wattage of the LED light source but also the light effect. The brightness is the wattage multiplied by the light effect.

210 lm/w LED chip

Attenuation rate of light after 5 years: 10%

110 lm/w LED chip

Attenuation rate of light after 5 years：80%

PVC cable with a copper conductor is not suitable for solar lighting systems,  PV cable with XLPE sheath and insulation and Tinned copper conductor without UL and TUV certificate is the best type of cable for the solar lighting system.

Top quality manufacturers of connector use nylon (PA66) and copper contacts with gold-plated which can use outdoors with the features of UV resistance and corrosion-resistant.

Polycarbonate lenses use in most solar lights but the best optical lens is high-temperature grade PMMA material with a 10-year no-yellowing guarantee with ZHAGA standards.

The charge controller is the brain of the solar lighting system.

It allows regulation and protection of the battery charge as well as the management of lighting and its programming.

The electronics parts of the Lumentek charge controller are completely encapsulated in an IP67 aluminum box providing it with tightness and perfect heat dissipation.

The MPPT charge controller also acts as a protection element for all components against:

• Overload
• Overcurrent
• Overtemperature
• Overvoltage
• Over-discharge

The black lamps look high-end in the photos and indoors, but if they are installed outdoors, the background of the environment is a blue sky, white clouds, and green trees, and light-colored lamps are more coordinated with the environment.

Black is the most heat-absorbing. The temperature of the metal shell can reach up to 90 degrees Celsius under exposure, and high temperatures will damage the battery and LED light source.

Black shell temperature up to 82.2 degrees Celsius

The temperature of the silver casing is significantly lower

Therefore, we recommend choosing a silver shell as much as possible, which will not absorb heat or fade when placed outdoors.

Automatic windshield wipers are not unique to the solar street light factory. This solution comes from a company in Shandong that makes solar power stations. Any solar street light manufacturer can purchase a ready-made solar windshield wiper solution from this company.

It is not practical to clean the wiper automatically, because adding this function will significantly increase the cost. If the motor is broken and the wiper stops on the solar panel, the entire solar panel cannot absorb sunlight also wiper system cannot clean solar panel without water.

Solar pole lights, solar panels are attached to the poles, and the effect of sunlight is very limited, and the absorption effect of solar energy is only 1/5 of ordinary solar panels. When the sun is at its maximum, that is, when the sun is directly above, the absorption effect of the pole solar panel is almost zero.

Solar charging is the conversion of solar energy into electric energy, and the DC power is stepped down and converted to DC power to charge the battery. Wind energy charging converts mechanical energy into electrical energy, and the alternating current is stepped down to direct current to charge the battery.

The two energy conversion mechanisms are different, and the conversion equipment used is also different. If you use wind energy to charge the battery of the solar street light, it will impact the battery and cause the battery to decay quickly. Wind energy and solar energy should not be mixed. At present, the solar and wind energy hybrid street lights on the market generally only have solar works, and the battery is not connected to the wires of wind energy.

Wind energy is only an imaginary project as decoration.

With consideration of all the above-mentioned points for the production of a good quality solar light, a custom-made solar lighting system designed based on Geographical location and customer demands will  demarcate  Lumentek comparing other manufacturers.