Understanding the Color Rendering Index (CRI) in Solar Street Lights

The Color Rendering Index (CRI) is a crucial parameter for evaluating the color rendering performance of solar street light sources. The higher the CRI, the better the color reproduction, and the visual effect is closer to natural light. This article analyzes the CRI values of different types of light sources and their impact on visual quality.

As a solar street light manufacturer, we understand that CRI directly affects lighting effects and user experience. Below, we provide practical advice from the perspectives of technical principles, scene adaptation, and product selection.

1. Comparison of Light Source Types and Color Rendering Characteristics

2. Impact of Solar Street Light CRI on Actual Effects

Safety and Functionality

• Low CRI (Ra<70): Red warning signs ΔE color difference >15 (international requirement ΔE<5), face recognition distance shortened by 30%.
• High CRI (Ra≥80): Vegetation layering improves by 50%, reduces “spooky feeling” complaints at night.

Economy and Energy Efficiency

• For every 10-point increase in Ra: Requires an 8% increase in battery capacity (e.g., 50W street light Ra70→Ra80 requires an additional 10Ah battery).
• Cost balance: High CRI LED premium is about 0.8-1.2 yuan/W, but maintenance cycle extends by 2-3 years.

Commercial Value

• Ra≥90: Product color saturation increases by 18%, night-time consumer conversion rate increases by 12% (measured data from commercial squares).

3. Scenario-Based Selection Scheme

Engineering Suggestions:

• Key area testing: Use X-Rite CA410 spectrophotometer to measure R9 (deep red) and R12 (deep blue) performance.
• Hybrid solution: Basic module (Ra70) + key supplementary light module (Ra90), balances cost and effect.

4. Technical Optimization and Quality Control Points

Spectral Enhancement Technology

• Violet-excited LED: Spectral continuity and similarity to sunlight reaches 92%, Ra≥95 and blue light peak reduced by 40%.
• Dynamic dimming: Automatically switches to low CRI mode (Ra85→70) during low traffic periods, extends battery life by 30%.

Attenuation Control

• Annual attenuation standard: High-quality products CRI annual decline ≤1.5, low-quality products can reach 5-8 points.
• Compensation circuit: Built-in current regulation module, offsets color rendering decline caused by LED chip aging.

Optical Design

• Compound lens: Secondary light distribution reduces invalid scattering, increases effective color rendering light by 15%.

5. User Purchase Suggestions

1. Certification standards: Request CIE S 025/E:2015 test report, focus on Rf (fidelity) and Rg (gamut index).
2. Warranty terms: Choose manufacturers that promise “Ra decline ≤3 within 5 years”, prioritize products supporting modular upgrades.
3. On-site verification: Use standard color cards (e.g., ColorChecker 24 colors) to compare lighting effects before installation.

Case reference: A certain ancient town project used LED with Ra95+R9>60, increasing night-time visitor stay time by 1.2 hours and shop revenue by 18%.

As a manufacturer, we recommend users choose a “sufficient and economical” color rendering solution based on actual needs, avoiding the cost waste brought by blindly pursuing high parameters. For customized solutions, we can provide spectrum simulation and energy consumption calculation services.

Tag: Solar Street Light CRI

LUXMAN SOLAR STREET LIGHT MANUFACTURER

What makes Luxman different?

Luxman Light puts its customers and quality first. The team boasts a wealth of experience with decades of hands-on knowledge in the lighting and new energy space.

As a global leader in photovoltaic lighting, Luxman partners with businesses to customize innovative power and sustainability solutions that are informed by many years of experience at the cutting-edge of photovoltaics.

+86 13246610420
[email protected]

This article summarizes essential formulas commonly used in solar street light design, integrating national standards and practical case studies from various papers:

1. Average Road Illuminance Calculation

Formula:
Eavg = (N × Φ × U × K) / A

• Parameter Description:
  • N: Number of fixtures
  • Φ: Total luminous flux per lamp (lm)
  • U: Utilization factor (0.4-0.6)
  • K: Maintenance factor (0.7-0.8)
  • A: Road area (m2) = Road width × Lamp spacing

Example:
6m wide road, lamp spacing 30m, using 10,000 lm LED, one-sided lighting:
Eavg ≈ (1 × 10,000 × 0.5 × 0.75) / (6 × 30) ≈ 20.8 lx

2. Solar Panel Power Calculation

Formula:
Ppv = Qday / (Hpeak × ηsys)

• Parameter Description:
  • Qday = PLED × Twork (Daily energy consumption, Wh)
  • Hpeak: Local annual average peak sunlight hours (check meteorological data, e.g., Beijing 4.5h)
  • ηsys: System efficiency (0.6-0.75, including line losses, controller losses)

Example:
Load power 80W, daily operation 10h, Shanghai Hpeak=3.8h:
Ppv ≈ (80 × 10) / (3.8 × 0.65) ≈ 324 W

3. Battery Capacity Calculation

Formula:
C = (Qday × D) / (DOD × ηbat × Vsys)

• Parameter Description:
  • D: Number of consecutive cloudy days (usually 3-5 days)
  • DOD: Depth of discharge (0.5 for lead-acid batteries, 0.8 for lithium batteries)
  • ηbat: Charge/discharge efficiency (0.85-0.95)
  • Vsys: System voltage (12V/24V)

Example:
Daily consumption 800Wh, 24V system, 3 days backup, lithium battery:
C ≈ (800 × 3) / (0.8 × 0.9 × 24) ≈ 138.9 Ah → Choose 150Ah battery

4. Solar Panel Installation Angle

Formula:
θ = φ + (5° to 15°)

• Parameter Description:
  • φ: Local geographical latitude
  • Winter optimization: latitude +10°~15°, summer optimization: latitude -5°

Example:
Nanjing latitude 32°, fixed bracket tilt angle set at 37° (32°+5°) to improve winter power generation.

5. Wind Pressure on Solar Panels

Formula:
F = 0.61 × v2 × A

• Parameter Description:
  • v: Maximum wind speed (m/s)
  • A: Wind-facing area of the photovoltaic panel (m2)

Example:
Panel area 2m2, design wind speed 30m/s:
F = 0.61 × (30)2 × 2 = 1098 N
Need to verify the wind resistance of the lamp pole and foundation.

6. Component Operating Voltage Correction (Temperature Effect)

Formula:
Vmp = Vmp(STC) × [1 + α × (T – 25)]

• Parameter Description:
  • α: Temperature coefficient (approximately -0.35%/°C for monocrystalline silicon)
  • T: Actual operating temperature (°C)

Example:
Nominal component voltage 18V, operating temperature 60°:
Vmp ≈ 18 × [1 – 0.0035 × (60-25)] ≈ 15.3 V

7. Voltage Drop Compensation Due to Temperature

Formula:
ΔV = Nseries × α × ΔT × Vmp(STC)

Example:
3 series-connected components, each Vmp=30V, temperature difference 35°:
ΔV ≈ 3 × (-0.0035) × 35 × 30 ≈ -11V
Need to adjust the MPPT voltage range.

8. Solar Panel Capacity Optimization Design

Empirical Formula:
Ppv(opt) = 1.2 × Ppv

• Consider shadowing, dust loss (efficiency reduction of 10-20%)
• When paralleling multiple components, increase bypass diodes to reduce hotspot effects.

9. Typical Design Parameter Comparison Table

Note: Actual design should be combined with PVsyst simulations and DIALux lighting simulations, and validated through field tests.