Solar street light government project Solutions and Procurement guide

Government Solar Street Light Project Guidelines

With the intensification of the global energy crisis and the rising awareness of environmental protection, solar street lights are gradually becoming an important choice in government projects as a clean, renewable lighting solution. This document aims to provide detailed guidance for governments in planning and implementing solar street light projects, covering aspects such as system design, component selection, installation requirements, and economic benefit assessment.

1. Government solar street lighting systems System Design

1.1 Geographic Location and Climate Conditions

The design of a solar street light system must fully consider the geographic location of the installation site, including latitude, longitude, and altitude. These parameters directly affect solar radiation intensity and sunshine hours.

• Berlin, Germany: Located at 13.40°E, 52.52°N, with an altitude of approximately 34 meters. The average actual sunshine hours in this area are 4.5 hours, with peak sunshine hours averaging 3.5 hours.
• Los Angeles, USA: Located at 118.24°W, 34.05°N, with an altitude of approximately 285 meters. The average actual sunshine hours are 7.5 hours, with peak sunshine hours averaging 5.5 hours.
• Sydney, Australia: Located at 151.20°E, 33.86°S, with an altitude of approximately 10 meters. The average actual sunshine hours are 6.5 hours, with peak sunshine hours averaging 4.5 hours.

1.2 Load Calculation

Calculating the electric load of the solar street light system is an important step in the design process. For example, in a project in Berlin, a 30-watt LED lamp is used for 8 hours daily, resulting in a daily load of 240 Wh. The system design should ensure sustainable power supply for seven consecutive rainy days. The formula is:

Wp = Q × 365 / (η × Hs)

where Wp is the capacity of the solar battery pack, Q is the daily electricity consumption, η is the system efficiency (0.6), and Hs is the solar radiation on inclined solar modules (MJ/m²). For example, a project in Berlin requires a light source power of 30 watts, operating for 8 hours daily, functioning normally for seven consecutive rainy days. The calculation indicates the optimal capacity of the solar battery pack is 100 Wp.

1.3 Solar Battery Pack Capacity Design

The capacity of the solar battery pack should be determined based on the daily electricity consumption, local geographic conditions, and climatic conditions. For instance, a project in Los Angeles uses a 100-watt monocrystalline solar panel to ensure normal operation for five consecutive rainy days. The optimal tilt angle of the battery pack is also a key design parameter; in Los Angeles, the optimal tilt angle is 34°, ensuring a balance of solar radiation in winter and summer.

1.4 Battery Configuration

The battery configuration should consider low-temperature discharge performance and burial methods. For example, a project in Sydney uses a 60 Ah lithium iron phosphate battery to ensure normal operation for five consecutive rainy days. The maximum discharge depth of the battery should be less than 60% to ensure long-term performance; for instance, in Sydney, the maximum discharge depth in January is 55%, meeting design requirements.

1.5 Communication Devices

The wireless data transmission module is a critical component of the solar street light system, supporting GPRS (General Packet Radio Service) with an RS-232 interface, a communication distance of up to 100 meters, and strong anti-interference capability. The communication device enables communication between adjacent lamp terminals, enhancing the intelligent management level of the system. For example, a project in Berlin adopted a smart controller with GPRS communication capabilities, ensuring stable operation under various weather conditions.

2. Government solar lighting Component Selection

2.1 Solar Panels

It is recommended to use high-efficiency, long-lifespan monocrystalline solar panels. Under standard light intensity (1000 W/m²), each square meter of monocrystalline solar panel can generate 120-140 watts. For example, a project in Los Angeles uses a 100-watt monocrystalline solar panel to ensure normal operation for five consecutive rainy days.

2.2 Batteries

Sealed lead-acid (VRLA) batteries are usually buried due to their large weight and volume. Special attention should be paid to waterproof measures in high groundwater levels and humid environments. If funds are sufficient, lithium iron phosphate batteries are recommended due to their light weight and compact size, suitable for pole installation. For example, a project in Sydney uses a 60 Ah lithium iron phosphate battery to ensure normal operation for five consecutive rainy days.

2.3 LED Lights

Select high-efficiency LED light sources to ensure their total luminous flux meets road lighting standards. LED fixtures should have good waterproof, dustproof, and sealing performance, achieving IP65 protection level. For example, a project in Berlin uses 30-watt LED lights to work 8 hours daily, ensuring normal operation for seven consecutive rainy days.

2.4 Smart Controllers

The smart controller is the core component of the solar street light system, requiring precise discharge control, intelligent infrared remote control, and stepless power control capabilities. The controller should also include overcharge and over-discharge protection, electronic short circuit, overload protection, and reverse connection prevention functions to ensure stable system operation. For instance, a project in Los Angeles adopted a smart controller with multiple protection functions, ensuring stable operation under various weather conditions.3

3. Government solar lighting projects Installation Requirements

3.1 Lamp Pole Installation

The lamp poles should be made from high-quality steel components, continuously automatically arc-welded to ensure smooth lines and beautiful shapes. The anti-wind and waterproof measures of the lamp poles need to be reliable. For instance, a project in Sydney uses 10-meter-high lamp poles, ensuring stability in high winds.

3.2 Installation of Solar PV Modules

The modules should be installed in positions that can fully receive sunlight, avoiding obstructions. If pole installation is used, the lamp post’s load capacity must be considered; if buried installation is chosen, adequate underground space must be ensured, free of buried cables and pipes. For example, a project in Berlin uses 80-watt solar panels installed at the top of the lamp pole, ensuring they are unobstructed.

3.3 Street Light Foundation

The foundation requirements for high-power solar street lights are higher than traditional street lights’ foundations may not meet. An overly large foundation can increase project costs and construction difficulty, thus requiring rigorous calculation and design. For example, a project in Los Angeles uses a concrete foundation, ensuring stable support for the street lights under various geological conditions.

4. Economic Benefit Assessment

4.1 Initial Investment Costs

The initial investment cost of the solar street light system includes the costs of solar modules, battery packs, smart controllers, LED fixtures, lamp poles, and installation materials. For example, the initial investment for a project in Berlin is €2000, for Los Angeles is $3000, and for Sydney is AU$2500.

4.2 Annual Electricity Savings

The annual electricity savings from the solar street light system can be calculated using the following formula:

A = Q × Pe

where Q is the annual savings in electricity, and Pe is the current electricity price. For example, in a project in Berlin, the annual savings can reach 105,120 kWh, equivalent to €26,280 per year; in Los Angeles, the savings can reach 365,000 kWh, equivalent to $54,750 per year; and in Sydney, the project can save 175,200 kWh, equivalent to AU$35,040 per year.

4.3 Dynamic Payback Period

The Dynamic Payback Period refers to the time required to recover project investment, considering the time value of money. The calculation formula is:

n = Initial Investment / (Annual Electricity Savings × (1 + i) ^ t)

where i is the social annual interest rate, and t is the time. For example, a project in Berlin has a dynamic payback period of 8 years, in Los Angeles 6 years, and in Sydney 7 years.

4.4 Static Payback Period

The Static Payback Period refers to the time required to recover project investment without considering the time value of money. The calculation formula is:

n = Initial Investment / Annual Electricity Savings

For example, a project in Berlin has a static payback period of 5 years, in Los Angeles 6 years, and in Sydney 7 years.

4.5 Net Present Value (NPV)

The net present value refers to the total discounted cash flow of the project over its entire life cycle. The calculation formula is:

NPV = ∑t=0n Ct / (1 + i)t - C0

where Ct is the net cash flow in year t, C0 is the initial investment, i is the social annual interest rate, and n is the project lifespan. For example, a project in Berlin shows a positive NPV over a 20-year operating period, indicating project feasibility; similarly, projects in Los Angeles and Sydney also show positive NPV over the same period, indicating good economic benefits.

5. Environmental Impact Considerations

5.1 Energy Conservation and Emission Reduction

The solar street light system has significant environmental advantages, reducing traditional electricity consumption and lowering carbon emissions.

• Berlin: The project can save approximately 105,120 kWh of electricity annually, equivalent to saving approximately 38.89 tons of standard coal, reducing carbon dioxide emissions by approximately 65.49 tons, sulfur dioxide by 0.27 tons, nitrogen oxides by 1.68 tons, and dust by 0.17 tons.
• Los Angeles: The project can save around 365,000 kWh annually, equivalent to saving about 131.75 tons of standard coal, reducing carbon dioxide emissions by approximately 227.75 tons, sulfur dioxide by 0.95 tons, nitrogen oxides by 5.95 tons, and dust by 0.59 tons.
• Sydney: The project can save about 175,200 kWh of electricity annually, equivalent to saving approximately 63.75 tons of standard coal, reducing carbon dioxide emissions by about 108.75 tons, sulfur dioxide by 0.45 tons, nitrogen oxides by 2.75 tons, and dust by 0.28 tons.

5.2 Greening and Obstructions

During project implementation, road environmental factors should be considered, such as trees and high-rise buildings that may obstruct solar panels, reasonably arranging streetlight locations, and using cantilever extensions to avoid obstructions. For example, a project in Berlin has utilized cantilevered designs for lamp posts to ensure solar panels are unobstructed.

5.3 Overhead Cables

Overhead cables should not run over solar panels to avoid affecting their generating efficiency. For example, a project in Sydney specifically paid attention to this in its design, ensuring all overhead cables were away from the solar panels.

6. Application Examples

6.1 Berlin, Germany

The city of Berlin has installed solar street lights on multiple streets, especially in parks and residential areas. For example, a project in Berlin uses 100-watt solar panels and 120 Ah batteries, with each street light having a power of 30 watts and operating for 8 hours daily. The design ensures normal operation during seven consecutive rainy days. The project saves approximately 105,120 kWh of electricity annually, equivalent to saving about 38.89 tons of standard coal, and reducing carbon dioxide emissions by about 65.49 tons, sulfur dioxide by 0.27 tons, nitrogen oxides by 1.68 tons, and dust by 0.17 tons. Calculated at a local electricity price of €0.25 per kWh, the annual electricity cost savings amount to about €26,280.

6.2 Los Angeles, USA

Los Angeles has installed solar street lights on several major roads, particularly in arid and sunny areas. For example, a project in Los Angeles spans 10 kilometers with 200 street lights, each with a power of 50 watts, operating for 10 hours daily. The project not only reduces electricity costs but also improves nighttime lighting in the city. It saves around 365,000 kWh annually, equivalent to saving about 131.75 tons of standard coal, reducing carbon dioxide emissions by approximately 227.75 tons, sulfur dioxide by 0.95 tons, nitrogen oxides by 5.95 tons, and dust by 0.59 tons. Calculated at a local electricity price of $0.15 per kWh, the annual savings amount to approximately $54,750.

6.3 Sydney, Australia

Sydney has installed solar street lights along several major roads, particularly in coastal areas. For example, a project in Sydney uses 80-watt solar panels and 60 Ah batteries, with each street light having a power of 20 watts and operating for 12 hours daily. The design ensures normal operation during five consecutive rainy days. The project saves approximately 175,200 kWh of electricity annually, equivalent to saving about 63.75 tons of standard coal, reducing carbon dioxide emissions by around 108.75 tons, sulfur dioxide by 0.45 tons, nitrogen oxides by 2.75 tons, and dust by 0.28 tons. Calculated at a local electricity price of AU$0.20 per kWh, the annual electricity savings amount to about AU$35,040.

7. Intelligent Design

7.1 Smart Controllers

The smart controller is the core component of the solar street light system, requiring precise discharge control, intelligent infrared remote control, and stepless power control functionalities. The controller should also include overcharge and over-discharge protection, electronic short circuit, overload protection, and reverse connection prevention functions to ensure stable system operation. For example, a project in Los Angeles uses a smart controller with multiple protection features to ensure stable system operation under various weather conditions.3

7.2 Time Division Dimming

The time division dimming feature can automatically adjust the brightness of street lights based on time and light intensity, further reducing energy waste and improving lighting efficiency. For instance, a project in Berlin employs time division dimming functionality to automatically adjust street light brightness based on time and traffic volume, both saving electricity and ensuring lighting effectiveness.

7.3 Stepless Power Control

The stepless power control feature can automatically adjust street light power based on actual demand, ensuring adequate lighting at different times. For instance, a project in Sydney uses this functionality to automatically adjust street light power based on nighttime traffic variations, enhancing system flexibility and energy-saving effectiveness.

8. Management and Supervision

8.1 Project Management

Municipal staff should strengthen supervision and management of solar street light systems, promptly discovering and resolving issues to promote the optimization and improvement of energy-saving schemes. For example, a project in Los Angeles has established a dedicated management team to regularly check the system’s operational status, ensuring normal functioning.

8.2 Data Monitoring

Implementing advanced smart control systems allows for monitoring the energy consumption of lighting fixtures and precisely controlling the illumination time of various road segments, further saving electricity resources. For instance, a project in Sydney adopted a smart control system to monitor the energy consumption of each street light in real-time, ensuring high-efficiency system operation.

8.3 Reporting System

In daily management, staff should promptly report regulatory situations, ensuring the safety and energy-saving nature of street lighting to provide good service to citizens and promote sustainable urban development. For example, a project in Berlin has established a comprehensive reporting system that regularly submits system operation reports to the city government, ensuring project transparency and reliability.

9. Conclusion

Through the above guidelines and suggestions, governments can better plan and implement solar street light projects, achieving energy-saving and environmental protection goals while enhancing the quality and efficiency of urban road lighting. Although the initial investment of solar street light systems may be high, the long-term operational costs are relatively low, with no electricity costs and minimal maintenance expenses. Therefore, when evaluating projects, both initial investment and long-term operating costs should be considered comprehensively to ensure the project’s economic feasibility and environmental friendliness.

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