Pyranometer Solar Radiation Sensor

Solar radiation is the energy source driving photochemical reactions, thermal effects, and atmospheric dynamics — making it a key parameter for air quality interpretation, building energy analysis, and environmental research. The Sensorbee Pyranometer (SB3662) measures hemispheric solar radiation from 0 to 1,600 W/m² using an ISO 9060 Spectrally Flat Class C thermopile with a rugged glass dome, delivering calibrated irradiance data across the full 285–3,000 nm solar spectrum. With IEC 61724-1:2021 Class B compliance and a unique ball-levelling mechanism, it integrates seamlessly with the Sensorbee Pro series for real-time solar irradiance monitoring.

How It Works

The pyranometer uses a thermopile detector beneath a precision glass dome that transmits solar radiation across the 285–3,000 nm spectral range — covering ultraviolet through the full visible and near-infrared spectrum. Unlike silicon photodiode sensors limited to 300–1,100 nm, the thermopile measures the complete solar energy spectrum reaching the Earth's surface. The thermopile generates a voltage proportional to the incident solar radiation intensity, which is converted to an irradiance reading in watts per square metre (W/m²).

The glass dome provides angular correction and protects the thermopile from environmental contamination. The anodised aluminium housing ensures long-term durability, while the integrated ball-levelling mechanism simplifies installation by allowing precise horizontal alignment without additional mounting hardware.

Calibration uncertainty is less than 2.4% (k=2), meeting the requirements for ISO 9060:2018 Spectrally Flat Class C classification and IEC 61724-1:2021 Class B compliance.

Why Solar Radiation Data Matters

Solar irradiance data supports environmental monitoring in several ways:

• Photochemical context — ground-level ozone forms through photochemical reactions driven by sunlight. Solar radiation data alongside ozone measurements explains the timing and magnitude of ozone episodes. High irradiance during warm days drives peak ozone formation; cloud cover and low sun angles reduce photochemical activity
• Temperature correction — solar radiation influences the thermal environment around monitoring stations. Irradiance data helps explain temperature variations and thermal effects on co-deployed sensors
• Atmospheric stability assessment — solar radiation is a key input for estimating atmospheric stability class (Pasquill-Gifford stability), which determines how effectively the atmosphere disperses pollutants. Dispersion models using on-site irradiance data produce more accurate predictions than those relying on cloud cover estimates
• Solar energy assessment — for sites considering or operating solar installations, the pyranometer provides direct measurement of the solar resource available at the monitoring location
• Building energy analysis — solar heat gain through building envelopes depends on incident irradiance. Continuous measurement supports thermal comfort analysis and HVAC load calculations

Measurement Performance

The pyranometer measures from 0 to 1,600 W/m² with calibration uncertainty below 2.4%. The 1,600 W/m² upper range exceeds the maximum clear-sky irradiance at sea level (approximately 1,000–1,100 W/m²), providing headroom for the irradiance enhancement that occurs when direct sun and reflected cloud edge radiation combine.

The 285–3,000 nm spectral range captures the complete solar spectrum from UV-B through the full visible and infrared bands. This broad thermopile response provides more accurate total irradiance measurement than silicon photodiode sensors, which are limited to approximately 300–1,100 nm and miss a significant portion of the solar infrared energy.

Compact, Weatherproof Design

At 330 × 65 × 230 mm and 500 grams, the pyranometer features a robust anodised aluminium housing built for long-term outdoor deployment. The -15 to +55°C operating range and 0–100% RH humidity tolerance ensure reliable operation across all seasons and climatic conditions. The universal wall/pole mounting bracket with included hose clamps simplifies integration with existing monitoring station masts.

Integration With Sensorbee Platforms

The pyranometer connects to the Air Pro 2 and Air Lite via the M8 interface. Solar radiation data is logged alongside all other environmental parameters and transmitted to the Sensorbee Cloud.

For a complete environmental and meteorological monitoring capability, the pyranometer complements:

• Wind sensor (SB3611) or wind and rain combo (SB3602) — wind and precipitation data
• Precision temperature and humidity sensor (SB3104) — ambient conditions
• O3 sensor (SB4272) — photochemical ozone monitoring where solar radiation drives ozone formation chemistry

On the Sensorbee Cloud, solar radiation data can be visualised alongside air quality measurements, enabling time-series analysis of photochemical relationships — for example, plotting ozone concentration against cumulative daily irradiance to characterise the photochemical ozone formation potential at a monitoring site.

Installation

Mount the pyranometer on a horizontal surface with an unobstructed view of the sky hemisphere. The sensor must be level — even small deviations from horizontal introduce systematic measurement errors, particularly at low solar elevations. Avoid mounting positions where buildings, masts, trees, or other structures shade the sensor at any time of day or year.

The M8 connector cable routes to the Air Pro 2 or Air Lite base station. No calibration, orientation alignment, or software configuration is required at the deployment site.

Maintain the sensor by periodically cleaning the optical surface — dust, bird droppings, and condensation residue on the photodiode reduce measured irradiance. A soft cloth and clean water are sufficient; avoid abrasive cleaning materials that could damage the cosine-corrected optics.

Applications

• Environmental monitoring stations — solar radiation as part of complete meteorological datasets for air quality assessment, dispersion modelling, and atmospheric stability classification
• Photochemical ozone analysis — solar irradiance data providing context for ozone formation and destruction chemistry in urban and suburban monitoring networks
• Solar energy site assessment — direct measurement of the solar resource at proposed or operational solar installation locations
• Building energy analysis — irradiance data for solar heat gain calculations, HVAC load estimation, and daylighting design assessment
• Agricultural monitoring — solar radiation measurement for crop growth modelling, evapotranspiration estimation, and growing degree day calculations
• Environmental research — high-resolution irradiance data for radiative transfer studies, surface energy balance analysis, and climate monitoring

Frequently Asked Questions

What is global horizontal irradiance (GHI)?

GHI is the total amount of solar radiation received on a horizontal surface. It includes direct beam radiation from the sun, diffuse radiation scattered by the atmosphere and clouds, and reflected radiation from the ground and surroundings. GHI is the standard measurement for characterising the solar resource at a location.

How does this compare to silicon photodiode pyranometers?

Silicon photodiode pyranometers are less expensive but measure a narrower spectral range (typically 300–1,100 nm), missing a significant portion of the solar infrared energy. The Sensorbee thermopile pyranometer covers the full 285–3,000 nm solar spectrum for more accurate total irradiance measurement, with ISO 9060 Class C classification ensuring reliable, standards-compliant data.

Does cloud cover affect measurements?

The pyranometer measures whatever solar radiation is present — including reduced irradiance under cloud cover. Overcast conditions typically produce 50–200 W/m², partly cloudy conditions produce highly variable readings, and clear skies produce the maximum irradiance for that time of year and latitude.

Does the sensor need regular cleaning?

Periodic cleaning of the glass dome is recommended — monthly in dusty environments, less frequently in clean environments. Contamination of the dome surface systematically reduces measured irradiance, potentially biasing long-term datasets.

Can I measure solar radiation on tilted surfaces?

The pyranometer is designed for horizontal (GHI) measurement. Mounting on a tilted surface measures the irradiance on that specific plane, which can be useful for solar panel performance assessment. However, the calibration is optimised for horizontal mounting; tilted measurements should be interpreted with this in mind.