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At the 15th PV symposium in Staffelstein, Germany, in March, a new means of analyzing data and controlling PV systems was presented by IST EnergieCom.
As IST’s next generation of analyzing equipment, PV-Watch replaces the company’s former measurement system, PV-Control (see PI 6/98, page 14). The stimulus for the new development was the desire to be able to monitor the separate generator strings. Criteria such as simple installation and uncomplicated operation were taken into consideration in conceiving the system. PV-Watch encompasses a system for measuring and logging data, which consists of an analyzing unit, a radiation sensor, and up to 100 string sensors. »The device observes the electricity in each string of a PV system, considers it, and sets off an alarm as soon as an error is found,« says Gerd Heilscher, head of IST EnergieCom, about the latest development. PV-Watch compares the radiation data with the electricity in each string via the analyzing unit. In this way an intelligent concept is put into action, in which interference effects are filtered out on the basis of various timing elements. This prevents unnecessary error reports, for example as a result of shading.
The concept is based on the knowledge IST gained during the 1,000 Roofs Program. If the device discovers an error in the system operation, the system operator is alerted via an acoustic and optical warning. The audio alarm is exportable by means of a relay exit. The device can be connected to any PV system configuration and used for analyzing systems of almost any size. The analyzing unit has a text display and is operated by a stored program controller. The PV-Watch’s radiation sensors have proven their value in other programs. The string sensor makes a galvanic separated current measurement possible in a range from -10 to 10A (AC and DC). A solar cable of any relevant wire size can be put through the sensor – even with a multi-contact plug. The system, which does require a laptop for the simple and safe installation, continually monitors itself while being put into operation. As additional options, IST EnergieCom offers energy balancing, alarm warning via SMS, and an upgrade to a remote observation system. The basic version of the PV-Watch costs approximately 1595 DM ($797 USD). Each string sensor costs an additional 85 DM ($42). IST EnergieCom GmbH Mike
Zehner
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