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The ISET Sensor fills a gap in the market

What is the capacity of a PV plant? In order to check actual energy production, this question must be answered precisely and reliably. A new solar radiation sensor can now do that at a reasonable price.

There are a series of devices on the market for measuring the energy yield of a PV plant. However, most are not acceptable in terms of price–performance relationship. The inexpensive products are lacking in terms of precise measurement and lifespan, while higher-priced devices fulfill these conditions, but are far too costly. Moreover, the majority are equipped with thermoelectric radiation sensors, which have a different spectral sensitivity, as well as different reflective and thermal characteristics, making them only conditionally comparable with a PV plant.
The new illumination strength solar radiation sensor developed by the Institute for Solar Energy Supply Technology ISET (Kassel) is now able to fill this gap. The greatest advantage of the instrument is its measuring cells. Technically, constructed in nearly the same way as a comparable PV module, the cell is the basis for a precise determination of the radiation strength. In addition, the ISET sensor has an integrated temperature probe, which corrects measured values. These two features guarantee a precise ascertainment of performance—and at an affordable price.
In addition, the ISET Sensor stands out through its simple and compact construction, which, in connection with its robust aluminum housing, predestines the device also for use in harsh conditions. The Stiftung Solarenergie can thereby successfully employ the sensor in Ethiopia.
The ISET Sensor has been tested by the Fraunhofer Institute. The instrument is produced by IKS Photovoltaik (, whereby every piece is calibrated on the basis of a reference sensor. The maximum deviation in measurement is ± five percent. It is priced at 459 euros (exclusive VAT).

Christian Schmidt is a scientific journalist in Zurich.

Source:  sun-connect 2 | March 2010 (p. 2)