Sunshine Pyranometer - SPN1

• Global (Total) and Diffuse irradiance in W.m-2
• WMO sunshine threshold: 120 W.m-2 direct beam
• No moving parts, shade rings or motorised tracking
• No routine adjustment or polar alignment
• Works at any latitude
• Precision ground glass dome

The new Sunshine Pyranometer is a meteorological class instrument, with built-in heater, designed for long-term outdoor exposure. It is an affordable alternative to shade-ring pyranometers, pyrheliometers and traditional sunshine recorders. The SPN1 is exceptionally easy to use; it needs no routine adjustment or polar alignment and works at any latitude. The SPN1 is protected by patents EP 1012633 and US 6417500.

An internal heater keeps the dome clear of dew, ice and snow down to -20°C (in still air conditions), ensuring reliable readings in difficult climatic conditions.

Direct and Diffuse Radiation

The Sunshine Pyranometer uses an array of seven miniature thermopile sensors and a computer-generated shading pattern to measure the direct and diffuse components of incident solar radiation. The SPN1 computes direct radiation by subtracting the diffuse from the global (total) radiation.

Sunshine Duration

The WMO threshold for bright sunshine is 120 W.m-2 in a plane perpendicular to the direct solar beam. The SPN1 uses an algorithm based on the ratio of direct to diffuse radiation, combined with their absolute values, to estimate sunshine duration to within a few percent of the WMO standard.

The SPN1 does not need to be adjusted or repositioned to track the sun - a distinct advantage over devices with shadow rings. There are no complex electro-mechanical assemblies and no burnt paper tracks to interpret.

Outputs and Logging

The Sunshine Pyranometer provides 2 analogue voltage outputs for global and diffuse radiation, and a digital output for sunshine duration, which can be connected to data loggers, such as the Delta-T DL2e and GP1. Readings can also be obtained directly from the RS232 port.

Applications

Application areas include air pollution studies, cloud cover research, ET and heat flux studies, canopy analysis, building energy management systems and PV (photovoltaic) efficiency monitoring.

Comparison with BF3 Sunshine Sensor

The SPN1 is a precision version of the BF3 Sunshine Sensor and although the two instruments have some features in common, there are important differences. These are summarised in the document: "SPN1 Sunshine Pyranometer Comparison with BF3 Sunshine Sensor" - please see link below in the Downloads and Documentation section.