Operating photovoltaic systems safely with high availability

PV power plants > 50 kW

High availability of large PV systems

PV power plants > 50 kW High

In medium to large photovoltaic systems, safety and availability of the system and protection of the operating personnel is very important. Any electrical isolation and the peak performance of the system play a substantial role in the selection of suitable monitoring measures. In general, it is important to locate the fault quickly and automatically. 

Product overview ISOMETER®
Market segment brochure Renewable Energy
Flyer Safe connection to the grid
Application Note EDS309x
Technical paper Operating photovoltaic installations safely and efficiently
Technical paper Electrical safety in control and auxiliary circuits
Technical paper: The largest photovoltaic system in Latin America

Recommended systems for insulation monitoring:

Recommended measuring and monitoring relays:

Recommended systems for insulation fault location:

DIN EN 60255-127
Measuring relays and protection equipment - Part 127: Functional requirements for over/under voltage protection

VDE-AR-N 4105

Anwendungsregel:2011-08 Erzeugungsanlagen am Niederspannungsnetz Technische Mindestanforderungen für Anschluss und Parallelbetrieb von Erzeugungsanlagen am Niederspannungsnetz

CEI 0-21

Regola tecnica di riferimento per la connessione di Utenti attivi e passivi alle reti AT ed MT delle imprese distributrici di energia elettrica (Reference technical rules for the connection of active and passive consumers to the HV and MV electrical networks of distribution Company) 

Specifieke technische aansluitingsvoorschriften voor gedecentraliseerde productie-installaties die in parallel werken met het distributienet


DIN V VDE V 0126-1-1

Selbsttätige Schaltstelle zwischen einer netzparallelen Eigenerzeugungsanlage und dem öffentlichen Niederspannungsnetz


Recommendations for the Connection of Type Tested Small-scale Embedded Generators (up to 16A per phase) in parallel with Low Voltage Distribution Systems


Recommendations for the Connection of Generating Plant to the Distribution Systems of Licensed Distribution Network Operators


Recommendations for the Connection of Generating Plant to the Distribution Systems of Licensed Distribution Network Operators

PV power plants <= 50 kW

Electrical safety at home

PV power plants

In small photovoltaic systems, protection of the house residents and possible operators (fire brigade, chimney sweep) is very important. The inverters are mostly factory-equipped with the appropriate safety equipment. They are only safe enough if they can also detect symmetric faults caused by moisture and dirt. At the point of transfer between the internal network and the general power grid, the voltage and frequency must be checked at a predefined range.

Network and system protection

Safe voltage and frequency levels

Network and system protection

Before internal generation systems (photovoltaics, water power, CHP, biogas, etc.) can feed electrical energy into the public grid, an automatic switching point must be installed between the generation system and the low voltage network. This checks whether the frequency and voltage fed in are within the specified range. The three-phase voltage monitoring relay is used to pre-configure numerous standard specifications at the touch of a button.