Table of Contents
Introduction: Why Is It Essential to Review Project Proposals Before Bulk Purchasing?
For projects involving municipal roads, rural roads, industrial parks, and residential communities, bulk purchasing solar street lights represents a long-term investment. Buyers should not focus solely on the price per unit, LED power, or solar panel wattage. They must also ensure that the entire system is suitable for the actual installation environment and meets the project’s lighting and battery runtime requirements.
Even when product specifications appear to meet the requirements, flaws in the initial design can still lead to problems after installation, such as insufficient illuminance, inappropriate luminaire spacing, and inadequate battery runtime during cloudy or rainy weather. In large-scale projects, resolving these issues after installation can result in additional equipment, labor, and transportation costs.
Therefore, before placing a formal order, buyers should thoroughly review road conditions, pole layouts, lighting designs, system energy configurations, product specifications, and project verification documentation.
I. Confirm Road Conditions and Project Site Information
The first step in developing a solar streetlight solution is to understand the project site. Road width, installation environment, local climate, and lighting requirements all influence luminaire selection and system configuration.
Buyers should provide suppliers with the following basic project information:
Project Information to Be Confirmed
| Information Item | Details to Confirm |
|---|---|
| Project Location | Country, city, and specific area |
| Road Width | Number of lanes and total road width |
| Road Type | Municipal roads, rural roads, park roads, etc. |
| Installation Environment | Buildings, trees, and other potential obstructions |
| Lighting Layout | Single-sided, double-sided, or staggered arrangements |
| Climate Conditions | Sunlight, rainfall, temperature, wind speed, and snow accumulation |
| Lighting Requirements | Nightly operating hours, illuminance requirements, and dimming schedules |
1. Road Width and Type
Different road types have different lighting requirements. Rural roads may prioritize basic visibility and wayfinding, whereas urban roads typically have more specific requirements for average illuminance, uniformity, and glare control.
Therefore, luminaires should not be recommended solely on the basis of road classification or LED power. The design must account for the actual road dimensions and applicable lighting standards.
2. Installation Environment and Solar Resources
Solar panels require adequate sunlight to generate sufficient electricity. Shading from buildings, trees, and other structures can reduce photovoltaic output. Suppliers should assess on-site shading conditions and base their system designs on the available solar resources during the project’s worst-performing month.
Established manufacturers in the industry, such as SRESKY, typically request road drawings, site photographs, and local meteorological data before preparing a quotation. They then determine whether an integrated or split-type solar streetlight solution is more suitable.
This approach of assessing site conditions before proposing a solution is an important initial indicator of a supplier’s technical professionalism.
If a supplier recommends a standard configuration without first asking about the project location, road width, sunlight conditions, and required lighting duration, buyers should request a reassessment of the proposal.
II. Review Light Pole Height and Luminaire Spacing
Light pole height and luminaire spacing directly affect road lighting coverage and uniformity. If poles are too short, lighting coverage may be insufficient. Excessive spacing between poles can create dark spots, while overly tall poles may require higher luminous flux from the luminaires to achieve the target illuminance.
1. Is the Pole Height Appropriate?
Pole height should be determined according to road width, luminaire light distribution, installation method, and applicable lighting standards.
The following values are preliminary design references rather than fixed requirements:
| Application Scenario | Typical Pole Height Reference |
|---|---|
| Courtyards and pedestrian areas | 3–5 meters |
| Community and campus roads | 5–7 meters |
| General rural roads | 6–8 meters |
| Urban roads | 8–12 meters or higher |
The actual pole height should be adjusted according to road classification and lighting calculation results.
Even when luminaires have the same rated power, their actual lighting performance can vary significantly depending on luminous flux and light distribution characteristics.
2. Is the Luminaire Spacing Appropriate?
Luminaire spacing is generally determined by pole height, road width, luminaire light distribution curves, and the overall lighting layout.
During the design stage, the ratio of pole height to installation spacing (S/H) can serve as a preliminary reference. However, this ratio alone is insufficient to determine whether a lighting design meets project requirements.
Buyers should require suppliers to provide a lighting layout drawing that clearly specifies road width, pole height, installation spacing, arrangement patterns, and luminaire positions.
Only by evaluating these parameters together can the suitability of the lighting coverage be properly assessed.
III. Review Illuminance and Luminaire Light Distribution Design
Illuminance is one of the key indicators used to evaluate road lighting performance. Buyers should not assume that higher LED power automatically means better lighting.
Actual performance also depends on luminous flux, luminous efficacy, light distribution curves, installation height, and luminaire spacing.
1. Do Not Focus Solely on LED Power
Buyers should request the following technical parameters from suppliers:
| Parameter | Primary Function |
|---|---|
| LED Rated Power | Indicates the luminaire’s power consumption |
| Luminous Flux (lm) | Indicates the total amount of light emitted by the luminaire |
| Luminous Efficacy (lm/W) | Indicates the amount of light produced per unit of power |
| Light Distribution Curve | Shows how light is distributed in different directions |
| Color Temperature (K) | Influences the visual appearance of the light |
| Color Rendering Index (CRI) | Indicates the ability of the light source to render colors accurately |
| Protection Rating | Indicates the level of protection against dust and water ingress |
Among these parameters, the light distribution curve is particularly important.
For wider roads, adequate lateral light distribution must be considered. For narrower roads, excessive light dispersion should be avoided to ensure that light is used efficiently within the intended area.
2. Focus on Average Illuminance and Uniformity
Road lighting designs typically require verification of average illuminance, minimum illuminance, illuminance uniformity, and glare control.
The specific performance requirements should be determined according to the applicable road lighting standards, road classification, and client requirements at the project location. A single generic illuminance value should not be applied to every project.
3. Request a Lighting Simulation Report
For large-scale projects, buyers should require suppliers to conduct lighting simulations using the IES files of the actual luminaires being considered.
Commonly used lighting simulation software includes DIALux and Relux.
The simulation report should include at least the following information:
- Road dimensions and light pole layout drawings.
- Luminaire models and corresponding IES files.
- Pole heights and installation spacing.
- Average and minimum illuminance.
- Illuminance uniformity.
- Illuminance distribution maps.
It is important to note that visual renderings cannot replace actual lighting calculations.
Buyers should also verify that the luminaire models used in the simulation correspond exactly to the products specified in the final procurement order.
IV. Review Solar Panel and Battery Capacity
The stable operation of solar streetlights depends on the proper coordination of solar panels, batteries, controllers, and LED luminaires.
Insufficient solar panel output may result in chronic battery undercharging, while inadequate battery capacity may prevent the system from meeting lighting requirements during prolonged periods of cloudy or rainy weather.
1. Calculate Daily Power Consumption
Assume that a solar streetlight has a rated LED power of 40 W and operates for 6 hours every night.
Its daily energy consumption is:
40 W × 6 h = 240 Wh
If the luminaire uses time-based dimming, calculations should be based on actual power consumption during each operating period rather than simply multiplying rated power by total operating time.
For example, if the light operates at 40 W for the first 4 hours and at 20 W for the final 2 hours:
| Operating Period | Power | Duration | Energy Consumption |
|---|---|---|---|
| First half of the night | 40 W | 4 hours | 160 Wh |
| Second half of the night | 20 W | 2 hours | 40 Wh |
| Total | — | 6 hours | 200 Wh |
Therefore, an appropriate dimming strategy also affects the required solar panel and battery configurations.
2. Verify Solar Panel Power
Solar panels must generate enough energy to cover daily lighting consumption while accounting for system losses.
A preliminary estimation formula is:
P = E ÷ (H × η)
Where:
- P = Required solar panel power (W).
- E = Daily energy consumption (Wh).
- H = Peak sun hours during the worst-performing month.
- η = Overall system efficiency.
Assume that daily energy consumption is 240 Wh, peak sun hours during the worst-performing month are 3.5 hours, and overall system efficiency is estimated at 70%.
The calculation is:
P = 240 ÷ (3.5 × 0.7) ≈ 98 W
The preliminary estimate is approximately 98 W.
However, actual solar panel selection must also account for module temperature, dust accumulation, shading, mounting orientation, charging losses, and appropriate design margins.
Therefore, the final panel specifications should not be determined solely by this calculation. They must be further verified against local climate conditions and specific project requirements.
3. Review Battery Capacity and Runtime
Battery capacity determines how long a solar streetlight can continue operating during consecutive rainy days.
A commonly used estimation formula is:
C = (E × D) ÷ (V × DoD × ηb)
Where:
- C = Battery capacity (Ah).
- E = Daily energy consumption (Wh).
- D = Required backup duration (days).
- V = Nominal battery voltage (V).
- DoD = Allowable depth of discharge.
- ηb = Efficiency of the battery and discharge circuit.
Assumptions:
- Daily energy consumption: 240 Wh.
- Required backup duration: 3 days.
- Battery voltage: 12.8 V.
- Allowable depth of discharge: 80%.
- Discharge circuit efficiency: 90%.
The calculation is:
C = (240 × 3) ÷ (12.8 × 0.8 × 0.9) ≈ 78 Ah
Therefore, the theoretical battery capacity requirement is approximately 78 Ah.
Actual battery selection should also consider low-temperature performance, battery aging, BMS protection strategies, and appropriate design margins.
4. Verify Compatibility Among System Components
In addition to checking component capacities, buyers should confirm that the solar panels’ operating voltage, controller charging current, battery type, and LED load are mutually compatible.
The system should also incorporate appropriate protection against overcharging, over-discharging, overcurrent, and relevant temperature-related risks.
Key Review Point: Do not rely solely on the rated specifications of solar panels and batteries. Request a complete explanation of the supplier’s energy calculations and system operating strategies.
V. Review Product Specifications and Core Components
After completing the design review, buyers must also confirm that the final delivered products conform to the approved design.
The following components and specifications should receive particular attention:
| Component | Key Parameters to Review |
|---|---|
| LED Luminaires | Power, luminous flux, luminous efficacy, and light distribution curve |
| Solar Panels | Type, rated power, voltage, and dimensions |
| Batteries | Type, voltage, capacity, and cycle performance |
| Controller | Charging/discharging parameters, protection functions, and dimming modes |
| Light Pole | Height, material, wall thickness, and surface treatment |
| Enclosure | Material, protection rating, and heat dissipation design |
| Fasteners | Material and corrosion resistance |
1. Focus on Battery Performance
Buyers should verify the battery type, rated capacity, operating temperature range, cycle life, and BMS protection functions.
Battery cycle life must be evaluated in the context of the specified testing conditions. Buyers should not rely solely on the cycle life figures advertised by suppliers.
In cold regions, particular attention should be paid to low-temperature charging protection. In high-temperature environments, the battery’s operating temperature range and heat dissipation conditions must be carefully evaluated.
2. Focus on Outdoor Protection and Structural Safety
Lighting fixtures must meet the project’s requirements for water resistance, dust resistance, and weather resistance.
For coastal projects, buyers should also assess resistance to salt-fog corrosion. In areas exposed to strong winds, the structural strength of the light poles, mounting brackets, and foundations must be verified against applicable local wind load requirements.
3. Verify Consistency Between Samples and Mass-Produced Products
Before formal mass production begins, buyers should verify the specifications of the sample’s LEDs, batteries, solar panels, controllers, and light poles.
Key component configurations should be clearly specified in the purchase contract.
Suppliers should not replace any core components without obtaining the buyer’s prior approval.
VI. Require Suppliers to Provide Project Validation Documentation
For large-scale projects, product catalogs and specification sheets alone are insufficient to demonstrate the reliability of a proposed solution.
Buyers should require suppliers to provide technical documentation that directly relates to the actual project.
1. Lighting Simulation Report
Verify the road dimensions, pole height, installation spacing, luminaire models, and IES files to confirm that average illuminance, minimum illuminance, and uniformity meet project requirements.
2. System Energy Calculation Report
The report should specify:
- Daily energy consumption.
- Required solar panel power.
- Battery capacity.
- Local solar irradiation data for the worst-performing month.
- Designed backup runtime.
- Dimming strategies.
3. Product Testing and Quality Documentation
Depending on project requirements, buyers may request documentation covering IP protection ratings, battery safety, luminaire photometric performance, electromagnetic compatibility (EMC), and relevant product certifications.
Buyers should verify that the product models, testing scope, and applicable standards stated in the documentation correspond to the actual products being procured.
4. Sample Testing or On-Site Pilot Installation
For large-scale projects, it is advisable to conduct sample testing or a small-scale pilot installation before proceeding with bulk procurement.
The evaluation should cover:
- Actual lighting performance.
- Nighttime operating duration.
- Dimming functionality.
- Battery charging and discharging status.
- Installation convenience.
Identifying potential problems during pilot testing can significantly reduce the risk of costly corrective work after bulk delivery.
VII. Checklist for Reviewing Proposals Before Bulk Procurement
Before placing a formal order, use the following checklist to confirm that the supplier has provided all necessary technical information and documentation.
| Review Item | Key Information to Verify |
|---|---|
| Project Conditions | Location, road width, installation environment, and climate |
| Lighting Layout | Pole height, spacing, and installation method |
| Lighting Design | Luminous flux, light distribution, illuminance, and uniformity |
| Solar Panels | Rated power and supporting power generation calculations |
| Battery System | Capacity, service life, and protection features |
| Control System | Controller specifications and dimming strategies |
| Product Structure | Protection rating, pole material, and structural design |
| Technical Documentation | IES files, lighting simulation reports, and energy calculations |
| Product Quality | Test data and certification documents |
| Sample Verification | Sample testing and batch consistency |
| Delivery and Acceptance | Inspection requirements, packaging, and acceptance criteria |
If any key technical documentation is missing, buyers should complete the review process before finalizing the bulk order.
VIII. Five Red Flags to Watch for When Reviewing Solar Streetlight Proposals
When evaluating supplier proposals, buyers should pay particular attention to the following warning signs:
1. The Proposal Includes Only Product Specifications, Without a Project-Specific Design.
The absence of a streetlight layout drawing and lighting simulation may indicate that the supplier is simply recommending standard products without conducting a proper project assessment.
2. The Supplier Focuses Exclusively on High-Power LEDs.
Without supporting data on luminous flux, light distribution curves, and illuminance, it is impossible to accurately evaluate the actual road lighting performance.
3. There Is No Supporting Basis for Battery Runtime Calculations.
Promises of a certain number of operating days during consecutive rainy periods are not technically meaningful unless supported by information on power consumption, battery capacity, and allowable depth of discharge.
4. The Configurations of Samples and Mass-Produced Products Are Not Clearly Defined.
If core components can be replaced without approval, the final delivered products may differ significantly from the samples that were originally tested.
5. The Quotation Is Significantly Lower Than Others, but the Supplier Cannot Explain the Configuration Differences.
Buyers should carefully verify the specifications of batteries, solar panels, luminaires, and light poles to avoid potential quality risks associated with unusually low prices.
IX. Frequently Asked Questions (FAQ)
Q1: How Many Consecutive Rainy Days Can a Solar Streetlight Operate Without Sufficient Sunlight?
This depends on battery capacity, daily energy consumption, allowable depth of discharge, and dimming strategies.
Buyers should require suppliers to provide supporting calculations rather than relying solely on verbal promises about the number of consecutive rainy days the system can withstand.
Q2: Why Do Solar Streetlight Samples Perform Normally but Deliver Insufficient Brightness After Mass Installation?
This may be caused by changes in the configuration of mass-produced products, insufficient solar panel output, inadequate battery capacity, mismatched luminaire light distribution, or differences in installation spacing.
Buyers should ensure that the core configurations of the approved samples, final design plans, and mass-produced products remain consistent.
Q3: Is Third-Party Testing Necessary for Large-Volume Purchases?
Third-party testing is not mandatory for every project. However, for municipal projects, government procurement, and projects with stringent quality requirements, third-party inspections or random sampling can be arranged according to contractual requirements and applicable local standards.
These inspections can help verify key indicators such as luminaire performance, battery safety, and protection ratings.
Q4: How Should Buyers Choose Between Integrated and Split-Type Solar Streetlights?
Integrated solar streetlights feature a compact design and are relatively easy to install, making them suitable for certain courtyards, residential communities, and small-scale road projects.
Split-type solar streetlights offer greater flexibility in photovoltaic panel placement, component capacity, and overall system configuration. They are generally suitable for projects with higher lighting or energy storage requirements.
The final selection should be based on local sunlight conditions, road lighting requirements, installation environment, and maintenance needs.
X. Conclusion: Review the Project Proposal Before Finalizing Bulk Purchases
The long-term stability of a solar streetlight project depends not only on product quality but also on the soundness of the initial design and the ability of solar panels, batteries, controllers, and LED luminaires to work together effectively.
Before placing a bulk order, buyers should carefully verify road conditions, lighting layouts, illuminance designs, system energy calculations, product specifications, and testing documentation.
Rather than simply comparing the price per unit or focusing on a single technical parameter, buyers should conduct a comprehensive evaluation to determine whether the entire solution meets the project’s actual requirements.
If you are evaluating solar streetlight suppliers, you can request that manufacturers, including SRESKY, provide customized technical proposals based on your project location, road width, required lighting duration, and battery runtime requirements. You can then compare the proposals based on their technical suitability and overall value.
A thoroughly reviewed project proposal can help buyers minimize product selection risks, reduce the need for post-installation adjustments, and improve the long-term operational reliability of solar streetlight projects.