Effective plant performance research requires an understanding of pyranometers, GHI, GTI, as well as benchmarking across solar plant blocks.
Accurate irradiance measurement is the basis of performance analysis in utility-scale solar plants.
What is a Pyranometer?
A pyranometer is a accurate sensor that measures solar radiation on a surface (W/m²).
It’s essential for:
- GHI (Global Horizontal Irradiance)
- GTI (Global Tilted Irradiance)
Key for PR calculation, fault diagnostics, real data validation, and prediction on expected energy output and plant pros and cons study
GHI vs GTI-What’s the Difference?
| GHI (Global Horizontal Irradiance) | GTI (Global Tilted Irradiance |
|---|---|
| Solar radiation on a flat surface. | Radiation on the module’s tilt. Better represents energy received by your panels. |
| Direct sunlight | Use GTI for real performance |
| Diffused radiation & Ground-reflected radiation | correlation across inverters |
Irradiance vs Insolation
| Irradiance | Insolation |
|---|---|
| Instant solar power (W/m²). | Total daily energy (kWh/m²/day) |
| 1000 W/m² at noon or real time. | Used in Helioscope, PVsyst. etc. to analysis |
Managing Multiple GTIs Across 3-5 km
When managing large solar sites with multiple blocks:
Installation Tips:
- Match module tilt & azimuth.
- Avoid shadow zones
- Clean glass regularly
- Calibrate every 2 years
Performance Checks:
- Compare GTis via SCADA or datalogger
- Acceptable variation: 3-5%
- Investigate if >5% consistently:
- Sensor drift
- Dirt or droppings
- Loose cables
- Local cloud pattern
Advanced Considerations
Spectral Mismatch: Pyranometers and PV cells behave differently under cloudy/filtered light.
Temperature Effect: Ensure ISO Class A-grade sensors for stability.
Ventilation Units: Prevent fog/dust on high-end sensors (e.g… SMP22, SR30).
Shadow Rings/Albedometers: For diffuse/reflected radiation data.
GTI-Inverter Drop Alerts: Use GJI drops + relay trips to predict snow/dust events or plant anomalies.
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