Monitoring systems System monitoring using Transclinic xi+ System for a permanent performance control of photovoltaic plants The unlimited functionality of a photovoltaic plant is crucial for its efficiency. The Transclinic xi+ device series continuously calculates/determines the current coming from individual strings or string groups as well as the voltage in a photovoltaic plant thus allowing a very detailed monitoring. Disturbances that might cause a decrease in profits are thus identified and can be eliminated without delay. Depending on the model, the Transclinic xi+ has between 4 and 14 inputs for measuring currents of up to 30 A per string. The current measuring is particularly reliable thanks to very linear and stable shunt resistances. The current and voltage measuring data are transmitted via ModBus RTU over EIA RS-485. Evaluation and presentation of the data can be done using the PV Plant software (pages 34 to 35). In addition to current and voltage, it is possible to control optional analogue and digital signals and to operate signalling devices via a digital output. The information obtained about the operational status provides a reliable monitoring mechanism for the photovoltaic facility, which will help you to optimise your yield. Current measurement The measuring of the string current is effected via precise shunt resistances in order to achieve high linearity. Digital output This digital output can be operated remotely. Thus, for instance, it is possible to operate signal units in case of maintenance. 28 Monitoring systems Voltage measurement Transclinic xi+ enables voltage measurements up to 1,000 V DC. In combination with the string currents, this allows the calculation of the generated output of a photovoltaic plant. +70 °C to –20 °C Temperature monitoring Transclinic xi+ is suitable for a large range of temperatures thus allowing a safe operation in the combiner boxes. In addition to this it determines the current temperature of the PCB. Analogue and digital inputs In addition to the analogue values of voltage, current and PCB temperature it is possible to utilise further analogue and digital signals. So, for instance, it is possible to monitor the status of the surge protection or to connect wind and irradiance sensors. 29 Monitoring systems Transclinic xi+ – permanent performance monitoring Supplemented with the PV Plant software program which has a module to manage the data and one to visualise it online or off-line, which offers several ways to access the operating data of the photovoltaic facility. The information about the operating condition of a photovoltaic plant is a crucial factor in yield optimisation. The aim of the monitoring function is to provide permanent monitoring of the system to allow timely action to be taken as soon as the processes are not working as desired. Using the Transclinic xi+ monitoring system Weidmüller has created a solution specially designed for photovoltaic systems that provides permanent performance monitoring. Transclinic xi+ INVERTER + + + – – Transclinic xi+ circuit diagram 30 g Power Supply 18...36 VDC Analoge input Analoge input Digital input Digital output X5 X8 X4 Modbus g SW2 IN2– IN2+ IN1– IN1+ GND IIN VIN GND IIN SW1 VIN 0V X6 24 V Modbus RS485 RTU X7 GND 485 X3 485– X1 485+ 485+ S1 S2 X4 S3 S4 Input DC– S5 S6 S7 S8 X1 GND 485 PV PANEL 485– Output DC– Modbus RS485 RTU TRANSCLINIC XI+ X2 Monitoring systems Full functionality of a photovoltaic system is critical in terms of its efficiency. In particular, the decreasing feed-in tariffs mean that it is highly important for the operators and investors that the system is functioning perfectly. As photovoltaic panels are connected in series in so-called strings, local incidents can often have wide reaching effects, either on the whole string or even on whole segments of strings which are connected together. Performance reductions There are many possible influences that can be considered when thinking about the possible causes of performance reductions: • Shadowing - Plants that grow over time -E rrors during the layout of the system thanks to the shadow cast from known obstacles (e.g. trees and parts of buildings) - Newly constructed buildings • Dirt / pollution - Plant pollen - Soot - Moss - Bird droppings • Decreasing panel properties - Resistance increase at solder points - Cell breakage - Impaired performance of diodes in junction boxes • Installation errors -P oorly fitted or missing cable lines / plug-in connectors • Other errors - Cable damage (e. g. animal bite) - Interference by unauthorised persons (e. g. theft) Depending on the effects of the cause, the yield of the plant may decrease by more than 10% compared to when there is errorfree operation. To prevent such losses in yield, Weidmüller offers an efficient monitoring solution with Transclinic xi+. The series continuously monitors the power from single strings or groups of strings as well as the voltage of a Photovoltaic system and thereby permits detailed monitoring of the system. Negative influences, which lead to reduced output, can be detected immediately allowing rapid repairs or adjustments to be made directly to the system. Continuous string monitoring The Transclinic xi+ devices are divided into a measuring PCB and a CPU PCB for data processing. With this set-up and depending on the model, it is possible to measure the values from between 4 and 14 strings, with a maximum current per string of 30 A. By detecting the performance in parallel of many strings, and deviations detected can be narrowed down to the affected string and its modules. The effort involved in fault elimination is therefore directly reduced. For comparative measurements of the modules in the affective strings, the Weidmüller analysis system CLINICS SOLAR can be used. Using it, any performance reducing panel can be easily detected, even when they appear normally externally. Connecting additional devices The currents and voltages measured by the Transclinic xi+ are digitised on the CPU PCV and transmitted via an RS 485 interface using the MODBUS RTU protocol. Additionally, other freely selectable analogue and digital signals can be controlled and signalling devices operated via a digital output. This permits the surge protection to be monitored. This allows targeted, proactive planning of maintenance work, as it can be directly determined which spare parts are needed and where they need to be installed. In the same way, wind and light meters can be directly connected without having to have a separate BUS address with its own logic. Temperature range So that year round operation is possible even with widely fluctuating weather conditions, Transclinic xi+ gives reliable performance outside (built into a combiner boxes) for guaranteed continuous operation in temperatures ranging from -20 to +70 °C. Additional reliability comes from the fact that the current PCB temperature is always measured and available. Simple system integration Transclinic xi+ is mounted on a DIN rail in the combiner boxes, and consumes little power. To connect into customer specific IT structures, only the MODBUS signal needs to be fed in. The protocol stack is naturally included with delivery. For PC based systems, the monitoring data are transferred using a MODBUS converter to a USB port, and are available there for further processing. 31 Monitoring systems Transclinic xi+ Transclinic 4i+ Transclinic 7i+ Transclinic 8i+ Transclinic 14i+ Technical data Maximum no. of strings Maximum current per string Measurement range Maximum voltage Supply voltage range Temperature range Communication Analogue input Number of analogue inputs Digital inputs Number of digital inputs Digital output Solid-state relay Number of digital outputs Power consumption Dimensions Maximum measurement error Note 4 7 8 14 30 A DC 3 ... 30 A DC 1000 V DC 19 - 36 V DC -20 ... +70 °C Modbus RTU over RS-485 0 ... +10 V or 0 ... 20 mA 2 0 ... 5 V low,15 ... 24 V high 1 20 A DC 3 ... 20 A DC 1000 V DC 19 - 36 V DC -20 ... +70 °C Modbus RTU over RS-485 0 ... +10 V or 0 ... 20 mA 2 0 ... 5 V low,15 ... 24 V high 30 A DC 3 ... 30 A DC 1000 V DC 19 - 36 V DC -20 ... +70 °C Modbus RTU over RS-485 0 ... +10 V or 0 ... 20 mA 2 0 ... 5 V low,15 ... 24 V high 20 A DC 3 ... 20 A DC 1000 V DC 19 - 36 V DC -20 ... +70 °C Modbus RTU over RS-485 0 ... +10 V or 0 ... 20 mA 2 0 ... 5 V low,15 ... 24 V high max 30 V DC/AC 50 mA 1 < 1500 mW 225 x 109.5 x 92.2 1 max 30 V DC/AC 50 mA 1 < 1500 mW 265 x 109.5 x 92.2 1 max 30 V DC/AC 50 mA 1 < 1500 mW 295 x 109.5 x 92.2 1 max 30 V DC/AC 50 mA 1 < 1500 mW 370 x 109.5 x 92.2 ± 1% (from full scale) ± 1% (from full scale) ± 1% (from full scale) ± 1% (from full scale) Ordering data Type Transclinic 4i+ Qty. 1 Order No. 1238100000 Transclinic 7i+ Transclinic 8i+ 1 1 1238110000 1238120000 Transclinic 14i+ 1 1238130000 Note Transclinic xi+ in operation TRANSCLINIC XI+ MOD BUS RS48 5 RTU supp ly 24 DC (+) ly 24 DC (– ) supp 32 MODBUS RS485 RTU