Monitoring of photovoltaic systems

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©Denis Lenardic
2001-2012
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Sunday
20th May, 2012
01:53

This page was last time updated on
7th Jun, 2011

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Monitoring & control of photovoltaic systems

"The heart of a fool is in his mouth, but the mouth of a wise man is in his heart."
(Benjamin Franklin)

Fronius monitoring

Inverter monitoring on PC screen
(Courtesy: Fronius)

Monitoring and control of photovoltaic systems is essential for reliable functioning and maximum yield of any solar electric system. The most simple inverter check (monitoring) can be performed by reading values on display - display (usually LCD) is part of (almost) each grid-connected inverter. Most important inverter (or grid) related parameters are available on-line. Values like PV array power, AC (grid) power, PV array current etc are usually available. For sophisticated monitoring and control purposes environmental data - like module temperature, ambient temperature, solar radiation, wind speed etc. - can also be data logged, stored and analysed later. Remote control and monitoring can be performed by various remote connections: analog modem, ISDN, GSM etc. The most common connection for local/remote control are USB (sometimes even RS232) for local monitoring, RS485 and powerline for inverter interconnection. For wireless connection Bluetooth and Wi-Fi are most common used. Additional services like satellite based monitoring (SPYCE) are also available.

Photovoltaic systems monitoring - features and applications

Local monitoring

Most simple way to perform local monitoring is display available on inverter or on inverter control unit. Other possibilities of local monitoring includes monitoring by local PC via RS232 connection and/or remote display located in living room for example (connection between inverter and display is usually wireless). The following parameters can usually be monitored, datalogged and stored in inverter's memory or external data logger for particular time (up to 1 year usually). Sometimes additional sensor related units (external or internal) are also required:

Array voltage - V_DC (V)
Grid voltage - V_AC (V)
Array current - I_DC (A)
Grid (injected) current - I_AC (A)
Array power - P_DC (W)
Grid (injected) power - P_AC (W)

Module temperature - T_module (°C)
Ambient temperature - T_amb (°C)
Solar radiation - G (W/m²)
Daily/monthly solar insolation - H (J/m²)
Wind speed - v

Personal Display Unit, courtesy Fronius

Personal Display Unit, Fronius
(copyright: Fronius)

Public displays

Public displays are widely used not only as public monitoring tool they are used as promotional or educational purposes as well. Communication between photovoltaic system and public display is usually realized via RS232 port, some producers offer also wireless connection. Most common display types are LCD displays, numbers can clearly be read from distances up to 40 m, depends on number sizes.

Public Display Unit, courtesy Fronius

Public Display Unit
(copyright: Fronius)

Satellite based monitoring

SPYCE (Satellite Photovoltaic Yield Control & Evaluation) is based on more than ten years of research by well-known European institutions. The SPYCE methodology was developed by the EU project PVSAT. Some of SPYCE's features are: Automatic failure detection and alarm dramatically minimizes any down time. Failures may be detected before expiry of warranty. No on-site radiation measurements are required. The SPYCE website allows access to the system's yields, reference values and analyses at any time. SPYCE is based on the latest EU research results. Data from the latest generation of weather satellites is employed. Data flow and the web portal are adaptable to the requirements of different manufacturers of PV systems and inverters. SPYCE is a service designed and provided by METEOTEST, a Swiss company, internationally known for its meteorological expertise. METEOTEST is independent of PV system manufacturers.

More about SPYCE...

Remote monitoring & communication

Remote control and communication between inverters can be realized with RS485 connection or via grid (powerline connection). Distances up to 1200 m represents no problem, several tenth inverters can be connected in chain and monitored at the same time. For remote monitoring different ways of communication can be used: Ethernet, Internet, dial up access, GSM etc. System can send alerts and status messages to the control center or user. Alerts and system messages can be send by SMS service, GSM, fax machine etc.

Compatibility

Please note that different monitoring equipment and communication possibilities of different producers are not compatible. For system monitoring inverters and control equipment of the same producer must be used.

Web control piggyback module produced by SMA, courtesy SMA Solar Technology AG

Web control piggy back module and remote control unit produced by SMA
(copyright: SMA Solar technology AG)

Sunny Boy Control, Hardware control unit, courtesy SMA Solar Technology AG

Sunny Boy Control - hardware control unit - backside view - connection for local monitoring (serial ports) and remote control are visible
(copyright: SMA Solar technology AG)

Data logging

Data can be stored in inverters memory or in external units (data loggers). Different solutions are available on the market. Some producers offer also additional memory increase or upgrade. Better data loggers offer monitoring functions (data logging) for various environmental and additional system related parameters what can give the user detailed overview about the whole system. Additional parameters that can be monitored are module- and ambient temperature, solar radiation, solar irradiation, wind speed (hybrid systems), in some cases also air pressure and air humidity (sophisticated electronic weather station) etc. Temperature sensors are usually PT100 or PT1000 sensors. Solar radiation is measured with reference solar cells (Si-mono), analog inputs of the control equipment are usually standard 4-20 mA or 0-10 V inputs. Digital inputs are also available and can be used for net-meter/control equipment interconnection.

Internal datalogger card for Fronius invertres, courtesy Fronius

Internal data-logger card
(copyright: Fronius)

Photovoltaic systems - control & monitoring

Monitoring of complex PV/hybrid systems, courtesy SMA Solar Technology AG

Monitoring of complex photovoltaic and/or hybrid systems
(copyright: SMA Solar Technology AG)

Data-Loggers
	INTERLiNK Solar - Der INTERLiNK Solar misst die erzeugte Energie mit Hilfe von Zählimpulsen des Wechselrichters oder Einspeisezählers, die Modultemperatur und die Sonneneinstrahlung. Die Standardausführung besitzt zwei digitale Eingänge die sich wahlweise als Impusleingang und/oder als Statuseingang für zusätzliche Fehler- oder Alarmmeldungen konfigurieren lassen. Languages:
Public displays
	Rico Electronic GmbH - Rico supplies standardized and individual large displays for many applications as for example for solar plants, climatic values, numbers of items, industrial need, paper industry, accident-free days, commissioning or date/time. Languages:
	HvG Engineering - german Company HvG is working in the field of classical hard- and software-engineering. On the hard- and software market you will mainly find special products under the name of HvG , for example display units and software for solar applications Languages:
Remote monitoring services & telemetry
	inAccess Networks - inAccess provides an integrated solution that continuously monitors and controls the equipment of Photovoltaic Plants aiming at the recognition of operation failures, performance measurements, security and access control as well as collection and recording of statistical data and provision of integrated reports. The PV plants can be managed remotely through the internet and the respective portal providing high degree of flexibility and accessibility. Languages:
	Sunny Portal - Sunny Portal is a web service from SMA Solar Technology AG which enables you to set up personal Sunny Portal web pages, on which you can visualize the data pertaining to your photovoltaic system. The Sunny Portal also archives this data. This means that you can access your system data via the Internet from any location worldwide. Sunny Portal offers a wide range of functions for monitoring and visualizing of your photovoltaic system. Languages:
	GreenPowerMonitor - GreenPowerMonitor is the all-in-one monitoring solution for grid-connected installations and for off-grid installations. Languages:
	Logic Energy Ltd. - Logic Energy Ltd. specialises in providing monitoring and reporting services via the Internet, principally for the renewable energy industry. Our systems allow remote monitoring of energy systems, reporting and control of failures all via a web browser. Our graphical interface is easy to use and understand and can be accessed from any web-enabled device, such as a mobile phone, from anywhere in the world. Languages:
	PVSoft - Premier produit de Soft4Energy. Logiciel de supervision et d'exploitation dédié au photovoltaïque, multi-centrales, multi-fabricants et multi-users, il est distribué en mode SaaS. Il propose non seulement des fonctionnalités de monitoring des installations industrielles et résidentielles, mais aussi des fonctionnalités de gestion de maintenance et de diagnostic avancé (masque, vieillissement, encrassement, etc.). Languages:
	Solar-Log - The ideal combination of monitoring device and evaluation platform. For every plant size, one or 100 plants, private or industrial. Languages:
	One-ID - Solar ID est une solution de gestion pour les installateurs solaires qui gére la supervision, la maintenance et le suivi administratif. Languages:
	QANTUM - QOS ENERGY is an engineering company specialized in performance monitoring of renewable energy infrastructures and monitoring of efficient energy use within building and industries. Proposed to integrators, investors, financier and operators in renewable energy, our solutions guarantee technical performances (Quality of Service/QoS) and economical control of investment done. Languages:
	skytron energy - Our systems allow remote monitoring of energy systems, reporting and control of failures all via a web browser. Our graphical interface is easy to use and understand and can be accessed from any web-enabled device, such as a mobile phone, from anywhere in the world. Languages:
	Solar CyBro - Solar Plant Supervisory System (SPSS) is complete hardware and software solution for monitoring and control of solar power plants. Photovoltaic panels and inverters are selected of different manufacturers, providing the best solution for each plant. Languages:
	Heliotronics Inc. - SunViewer.net™ is a powerful, interactive tool that enables you to view the performance of your distributed generation systems over the Internet. In addition to graphing a variety of quantities of interest, SunViewer.net™ allows users to download data in a spreadsheet compatible format for further analysis. Languages:
	WattSure - Measure and monitor LIVE how solar thermal, photovoltaic systems and wind turbines are performing along with many other energy sources including mains electricity. WattSure is an energy management service that provides real time data about the performance of energy systems in the home or in the wider commercial environment. Languages:
	Fat Spaniel technologies - Critical Monitoring and Reporting Services for Renewable Energy Systems. Languages:
Remote monitoring & control - monitoring portals
	IBC SOLAR AG - Here you will find a selection of IBC solar power plants. For each system, a current performance analysis is shown, which will enable you to get an impression of monthly yield on plant. Languages:
	SolarMax Portal - Monitoing portal of Sputnik Engineering - Solar Max inverters. Languages:
	PV Labor der HTI Bern - PV laboratory monitors several grid connected photovoltaic power plants located in swiss Alps on high altitudes. Languages:
	Walter Grotkasten Portal - private owned PV monitoring portal. Languages:
	PV Log - PV monitoring portal for PV systems equiped with InterLink-solar Solardatalogger. Languages: