Standalone Sun Duration Sensor

Sun sensor overview

A Standalone Sun Duration sensor system designed to display daily sunshine hours (with midnight reset). Also displaying accumulated sun hours and first and last sun times.

The standalone sun sensor comprises of 3 components, the sunshine hours display, a junction control box and the sun sensor. The display is available as standard with an LCD readout and the option of an OLED readout which is backlit.

The mini junction control box is the standard interface. This can be used between either sun displays as well as both types of sun sensors. The large junction control box has the addition of a volt free contact. This allows the sun sensor to also be connected to a Davis weather station display.

There are 2 options of sun sensor, the standard and the infrared (IR) sun sensor.

The addition of a sun data logger can be used to record and file sun data. The power supply transformer as well as sensor, display cables are all supplied as standard.

Standard sensor

The sensor works by comparing the output of eight light sensitive diodes. The diodes surround a central shadow pillar. A shadow cast by this pillar on the diodes, allows the control box to register an electrical imbalance. This determines the sun to be shining and starts to generate a count (0.01 hours per count).

Instromet standard sun sensor part no. 480 1000 151.

The Instromet sun sensor features a laboratory grade glass dome. This allows improved product cleaning as well as servicing. We fit a desiccant into the sensor to ensure no misting in the dome. We protectively coat our aluminium sensor housings to give them improved weather resistance. There are screw terminal fittings to give ease of the senor cable connection. Supplied with 25 metres of sensor cable as standard. Extra cable in 25 metre lengths up to a max of 100 metres available.

IR filtered sensor

We now offer an improved version of our standard sensor. This version has infrared (IR) filtered light sensitive diodes fitted. These diodes only measure light within the World Meteorological Organisation’s guidelines for sun duration. The IR diodes have so far seen the sensor accuracy move to within 2% of more widely regarded products.

Instromet standard IR filtered sun duration sensor
Instromet standard IR filtered sun sensor part no. 480 1000 158.

Sun sensor review

Over the past decade or so, this simple, reliable, consistent and reasonably-priced sensor has become the sunshine sensor of choice for most of the amateur and hobbyist weather observing community within the UK and Ireland.

From The Weather Observer’s Handbook by Stephen Burt (Cambridge University Press, 2012 Handbook Details, reproduced by permission of the author and Cambridge University Press. See also

Sun sensor system options

We have three main options for system builds of our Stand alone sun duration sensor.

We have put this chart together to provide further details of each system.

Further and more detailed information regarding each system can be found below:

Hobbyist sensor details, setup and user guide.

Pro sensor details, setup and user guide.  

Remote sensor details, setup and user guide.

Each system has a twin counter readout to view the sun data. This counter also displays the first and last times of the day that sun is received by the sensor. There is the option to connect to our data logger with bespoke software via the systems ‘AUX’ output.

Sun Sensor Data logger

In addition to our standalone systems, we make a purpose built data logger which uses its own dedicated software.

Instromet sun duration sensor data logger
Instromet sun data logger part no. 480 1000 197.

Sun Duration Sensor Davis Interface

The Davis interface is for use as an expansion for the above system. This allows the standalone sun sensor to be connected to a spare Davis rain input. This interface activates the Davis input when the sun control box emits its pulse output (1/100 hr). The interface uses an optical transistor for its output. This means that both systems are kept electrically isolated from one another. This is an ideal addition to either the remote system or the Hobbyist version of the stand alone system. The Pro version sun system has its own ‘volt free’ contacts fitted which operate the same as this interface.

Davis sun interface part no. 358 6000 004
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