A 2025 smart city project in Gujarat reported stunning energy savings—solar street lights using dual light and time control modes saved 47% more energy compared to traditional light-only systems. Meanwhile, a rural project in Rajasthan experienced 3 days shorter battery life during monsoon due to incorrect mode priority settings. This highlights a crucial insight: mode synergy outperforms single-mode control under India’s diverse climate conditions.
This guide breaks down the working logic of dual light and time control—from activation thresholds to time-slot planning—with real cases from Delhi’s city roads and Madhya Pradesh's village pathways. We also provide a region-wise parameter guide to ensure reliable performance from the Thar Desert’s sun to West Bengal’s dense fog.
How Dual Mode Works: Light Activation + Time-Based Power Management
Dual mode isn’t just about combining two controls—it’s about dynamic priority management. Take the Systellar Innovations SK-300 controller as an example:
- Light control triggers the system when ambient light falls below 10 lux.
- Time control then adjusts power output according to preset intervals—e.g., 100% from 18:00–20:00, then 30% after 20:00.
This hybrid approach avoids false triggers on cloudy days (a flaw in light-only control) and adapts to seasonal daylight changes (a weakness in time-only control).
Setting the Right Activation Threshold
Uttar Pradesh municipal tests showed that setting the light activation threshold to 8 lux (instead of the default 5 lux) reduced false starts during monsoon from 12 to just 3 per month, while still ensuring lights turn on promptly on overcast days.
Formula:
*Activation Threshold (lux) = Local Minimum Daylight Intensity × 0.8*
Example: Rajasthan winter twilight ≈ 20 lux → Set threshold at 16 lux.
Time-Slot Planning Based on Traffic
Delhi Municipal Corporation uses a three-phase control on main roads:
- 18:00–22:00 (Peak): 100% power (60W)
- 22:00–05:00 (Off-Peak): 30% power (18W)
- 05:00–06:00 (Dawn): 50% power (30W)
This cut daily consumption per light from 0.6 kWh to 0.32 kWh.
Madhya Pradesh rural roads use an even more aggressive five-phase control, maintaining light for 7 continuous rainy days—40% longer runtime than single-mode systems.
Customizing for Urban & Rural Indian Conditions
India’s diverse settings require location-specific tuning. Below are MNRE-certified configuration examples:
Urban Roads (e.g., Delhi–Gurugram Expressway)
- Light Control: ON at 10 lux, OFF at 15 lux
- Time Control: 18:30–21:00 (100%) → 21:00–06:00 (40%) → 06:00–06:30 (60%)
- Logic: Time control dominates during set intervals; light control acts as backup
- Outcome: In a Jaipur pilot, this saved 52% energy and reduced accidents by 18%
Rural Roads (e.g., Madhya Pradesh PM-KUSUM Project)
- Light Control: ON at 8 lux, OFF at 12 lux
- Time Control: 18:00–20:00 (100%) → 20:00–05:30 (20%)
- Logic: Light control has priority; time control assists
- Extra: PIR motion sensor (8 m range) boosts light to 100% when people are detected
- Outcome: Runtime extended from 5 days to 7 days
Coastal Highways (e.g., Tamil Nadu Fishing Villages)
- Light Control: ON at 6 lux (fog-adjusted), OFF at 10 lux
- Time Control: 17:30–22:00 (100%) → 22:00–06:30 (30%)
- Extra: Humidity sensor increases power by 10% when RH > 90% to compensate for light loss
Controller Setup Guide: From Parameters to Troubleshooting
Even advanced controllers underperform if set up incorrectly. Follow these standardized steps (based on MNRE-certified Luminous SC-200):
Basic Configuration
- Mode Selection: Choose “Dual Mode” → Set priority (“Time Priority” for urban, “Light Priority” for rural)
-
Light Thresholds:
- Start Lux: Based on NISE solar data (e.g., 12 lux for Gujarat)
- Hysteresis: ≥5 lux to avoid frequent on/off near threshold
-
Time Programming:
- Up to 8 time slots (3 recommended for cities, 2 for villages)
- Set power % per slot (e.g., 30% for 18W/60W light)
Validation & Testing
- Light Threshold Test: Gradually cover PV panel; check if lights start at set lux and power adjusts per time plan
- Season Simulation: Use “Force Mode” to mimic winter daylight (8 hrs), verify runtime
- Fault Test: Disconnect light sensor; system should switch to time-control mode
Common Issues & Fixes
- Mode Conflict: Increase hysteresis to 8 lux
- Low Monsoon Runtime: Enable “Rainy Mode” to shorten peak hours by 2 hrs
- False Starts: Add a 10-minute delay relay to the light control circuit
Energy Savings & Case Data: How Dual Mode Saves 47%
Delhi Municipal Project (2024, 12,000 lights of 60W)
- Before: Single light control → 0.6 kWh/day, 17% failure rate in monsoon
- After: Dual mode (10 lux + 3-phase time control) → 0.32 kWh/day
- Outcome: 1.27 million kWh saved/year, 920 tons CO₂ reduction, 60% lower maintenance
Madhya Pradesh Rural Project (2025, 8,000 lights of 30W)
- Setup: 8 lux + 2-phase time control + PIR
- Result: 7 days runtime in continuous rain; 2.3 extra days vs. light-only mode
Tamil Nadu Coastal Project (2025, 5,000 lights of 40W)
- Challenge: Salt fog reduced sensor sensitivity
- Solution: Dual mode + quarterly calibration
- Outcome: Sensor replacement cycle extended from 6 to 18 months
Quick Parameter Table by Indian Region
| Region Type | Light ON Threshold | Time Slots | Power Strategy | Example Case |
|---|---|---|---|---|
| Northern Arid | 12–15 lux | 18:30–21:00 (100%) | Drop to 20% at night | Rajasthan Highways |
| Northeastern Rainy | 5–8 lux | 17:00–22:00 (100%) | Add 3rd slot in continuous rain | Assam Tea Estate Roads |
| Southern Coastal | 8–10 lux | 18:00–22:30 (100%) | +10% power if RH > 90% | Tamil Nadu Port Roads |
| Urban Core | 10 lux | 3-phase (Peak/Off-peak/Dawn) | Dynamic adjustment with traffic | Delhi Connaught Place |
| Rural Roads | 8 lux + PIR | 2-phase (Evening/Late Night) | Boost to 100% when motion detected | MP PM-KUSUM Project |
Action Plan: 3 Steps to Configure Dual Mode
Step 1 – Data Collection
- Get local solar data from IMD (www.imd.gov.in)
- Study traffic flow (install vehicle counters if needed)
Step 2 – Parameter Calculation
- Light threshold = Local min. daylight × 0.8
-
Time slots:
- Peak: >50 vehicles/hour → 100% power
- Off-peak: <10 vehicles/hour → 30–50% power
-
Logic:
- Urban: Time priority, light control as backup
- Rural: Light priority, time control for forced shutoff after 5 AM
Step 3 – On-site Tuning & Monitoring
- Monitor for 72 hours after installation
-
Adjust with season:
- Summer: Start time control 1 hour earlier
- Winter: Reduce light threshold by 2 lux
In Indian solar street light projects, dual mode control is not an option—it’s essential. It ensures 98% lighting reliability with over 40% energy savings. That’s why 87% of 2025 government tenders mandate dual-mode controllers.
