The market for photovoltaic systems is growing inexorably and becoming ever more important. In the meanwhile, installation of photovoltaic systems has already become a part of the standard repertoire of the electricians. However, the PV installation requires some rethinking during planning, dimensioning and component selection. In order to facilitate the work of the electrician and to ensure maximum system availability, Hensel has developed standardised system solutions, which are fine tuned to the specific requirements of the PV installation. Hensel is the leading, internationally operating vendor for electrical installation and power distribution systems with high innovative power. The German company is known world-wide for its distribution solutions which provide safe power distribution with their heavy duty properties. It is not a coincidence that Hensel solutions are being used, for example, in large industrial and commercial enterprises world-wide. Decades of experience and the constant dialogue with the customers form the basis for the innovative solutions provided by the company. Hensel started developing special installation solutions for the special requirements of a photovoltaic system quite early. The requirements for the interfaces between the individual components differ distinctly from the requirements for classical power distribution. The result is the ENYSUN distribution program, which offers correctly dimensioned distributors conforming to the standards in modular design to the electrician, which ensure safe operation at high system availability.

PV Components

A PV system consists of various components, which must be electrically interconnected to the interfaces. The main components are PV modules and inverters. To start with, several PV modules are interconnected to form PV strings. Several such strings then form a DC power supply unit, a so-called PV generator. Each PV generator supplies DC voltages of up to 1,000 V. The PV generators are connected via PV generator junction boxes to the inverters, which convert the direct current into alternating current. Several inverters are again interconnected via inverter collectors. From there it is linked to the grid connection or the supply to the consumer.

For all these interfaces, Hensel offers specially developed distribution solutions, which are fine-tuned to the respective requirements.

Different Requirements

The requirements for the various components are thereby very different. Since the PV generator junction boxes installations are predominantly outdoors, the devices are exposed to many various effects. In order to ensure long-lasting high operating safety, they must be able to handle with climatic requirements such as sun, rain, heat, frost and UV radiation. At the same time they must be resistant to mechanical effects. Impact strength, protection against accidental contact and foreign bodies, corrosion resistance as well as burning behaviour make high demands on material and design. They also make high demands distribution boards for power supply and measuring. Although they are usually located inside buildings and are thus protected, they also make high demands as regards safety, EMC compliance and maintainability.

PV Generator Junction Boxes

PV components on the Direct Current side needs to be seen as placed under voltage, even if the system is separated from the alternating current side. A protection according to protection class II or equivalent should be used preferably. It is required, when, for example, the DC networks are not earthed. In such a case, empty boxes which are tested in accordance with IEC 60 439 and fulfil the requirements of protection class II may only be used. Attention: Cable junction boxes in accordance with IEC 60 670-22 may not be used, since this standard does not envisage products of the protection class II. Within the ENYSUN product line, Hensel offers special PV generator junction boxes conforming to the standards for this area. The housings made from impact and UV resistant themoplastic are ready for connection and already pre-wired and equipped with over-voltage protection and are thus ready to use. Plug-in connections for the PV strings and the inverter also save installation time.

Inverter-collector

On the AC side, inverter collectors provide the connection between inverters and the power distribution. For this area, high flexibility is required in the installation, since the requirements differ from installation to installation. Therefore Hensel offers the ENYSUN inverter collectors as modular housing sets, which can be individually customised for the respective environment. Unlike the distributors in buildings, for which the simultaneity factor ranges from 0.3 to 0.6, it is 1 in photovoltaic systems. This must be taken into consideration when dimensioning the distributors. In case of wrong dimensioning, the dissipated power can lead to the equipment exceeding its maximum temperature, meaning that the protective equipment will trip at levels below the rated current. ENYSUN PV inverter collectors from Hensel are characterised by devices set at a distance, additional ventilation slots and larger housings. The dissipation of the energy is thereby markedly improved and a safe operation is ensured. Standard assembly aids for the optimum positioning on the DIN rail as well as for protection cover facilitate the assembly.

Connecting to the Power Supply Network

An interface to the infrastructure must be present to be able to feed the generated power to the power supply network and to bill the same. For this purpose, distribution boards and switchgear assemblies are suitable in various different designs. The dimensioning depends on the one hand on the capacity of the PV system and on the other hand on the requirements of the electric power supply. Thus, the systems must offer place for the measuring instruments and the connections of the inverter collectors. In some cases, an isolator is also required, which can be effected manually or automatically by monitoring of the network parameters. For this area, Hensel offers a broad spectrum of suitable solutions. In the area of the power distribution boards with measuring, the Hensel distribution solutions have likewise proved themselves. The wide Hensel product range ensures the optimum solution for every requirement.

(Hensel Electric India Private Limited, Chennai. Tel: 044-24542669/1654. Fax: 91-44-24541285. Email: info@hensel-electric.in)