Type tested modular junction boxes meet solar power needs
Modular junction boxes from CEE Norm help bring a communally operated solar power plant to the roof of the Frankfurt fairground.
The roof of Hall 10 of the Frankfurt Messe fairground is now home to a solar power plant - an innovative, communally operated project that will meet the electricity needs of over 150 homes. Key to the success of the installation are Hensel ENYSUN type-tested distribution boards and modular, pre-wired photovoltaic junction boxes - products distributed exclusively in the UK by Telford-based electrical specialist CEE Norm.
The communally operated photovoltaic plant is the result of the work of the Verein Sonneninitiative eV and Messe Frankfurt, with support from local power supply company Mainova. Messe Frankfurt GmbH employees at the Frankfurt fairground, and members of Sonneninitiative eV are among the investors. Messe Frankfurt rents out the roof space to the association.
The plant was installed by Elektro Blitzschutz Scholl from Ober-Mörlen, Germany, a specialist for photovoltaic plants. The first phase of construction was completed in only five weeks, and 300kWp of capacity brought on line. The mayor of Frankfurt and the chairman of the supervisory board for Messe Frankfurt, Dr Petra Roth, inaugurated the plant, along with Uwe Behm - the managing director of Messe Frankfurt - and Volker Klös chairman of the Sonneninitiative eV. Only three months later, capacity was expanded by 190kWp, with 2,097 solar panels - the largest installation of its type in Frankfurt - now providing an overall capacity of 490kWp. The 'annual harvest' is expected to be in the region of 455,000 kWh, meeting the electricity needs for more than 150 domestic households.
The ability to harvest such quantities of energy efficiently depends high performance components. To meet these requirements, Elektro Blitzschutz Scholl turned to Hensel, whose product range includes all of the necessary installation and distribution board systems for photovoltaic plants from PV generator junction boxes to PV inverter collectors and extensive accessories.
An advantage of the modular ENYSUN photovoltaic installation solutions from Hensel is that they are fully type-tested to the meet IEC 60 364-712 requirements, a standard created solely for the assembly of photovoltaic power plants. This dramatically simplifies the selection, specification and assembly of distribution systems for photovoltaic power plants, from the generator junction boxes to the PV inverter collector and all the necessary accessories. The components used in photovoltaic power plants have to meet challenging requirements. On roofs they are typically exposed to sun, rain, ice and snow. They have to operate both in the high temperatures in summer and in the freezing cold of winter. And the components also have to be resistant to constant UV radiation. Hensel distribution boards meet all of these requirements
Further protection is provided by the optional 'combi' climate glands, which employ a special membrane to ensure that outdoor installations are not subject to damaging quantities of condensation and that the high IP65 degree of protection is maintained.
The first phase of construction of the Frankfurt plant used collectors and distribution boards that were custom made. Power from the 33 inverter collectors is gathered into a collector and is sent to a transfer station using only two 4x240/120mm2 cables. Mi distribution boards from Hensel were used as collectors. The feed to the single phase inverter collector uses 63A miniature circuit breakers (MCB), each of the three are secured via an HRC00 fuse switch disconnector and mounted on a 630A busbar. The fuse switch disconnectors also provide backup protection. The connection to the feeding point is created using an HRC2 sized fuse for each.
Sheet steel encapsulated low-voltage SAS 2000 switchgear assembly from Hensel was used as the feeding point to the grid. The plant has a 630A circuit breaker on both the input and output sides. The transformer for electricity metering is mounted in between on converter brackets.
The second construction phase saw more use of Hensel distribution boards - this time type-tested ENYSUN photovoltaic inverter collectors. These were supplied as complete sets containing all of the components required, eliminating the time consuming task for the installer of assembling the various components.
The capacity of twelve inverters are consolidated in two inverter collectors. A Hensel SAS 2000 low-voltage switchgear assembly was installed as a transfer station. Three parallel cables from the collectors were secured using an HRC1 fuse switch disconnector. On the output side, a 630A circuit breaker is responsible for the connection to the Mainova grid.
Hamburg-based Zeikon is responsible for monitoring the plant, collecting operational information from dataloggers over an internet connection. It is also responsible for ongoing maintenance. For maximum plant availability, it is important that the components installed offer assured long term reliability and that operational disruptions are avoided as far as possible. This was a further key in the use of Hensel distribution boards, as Zeikon master electrician, Matthias Scholl explains: "We have worked with Hensel products for years and found them to be very reliable. Further, Hensel is the only supplier of safe and practice-oriented distribution board solutions that conform to photovoltaic plant assembly standards, with all the test certificates to back it up. And since Hensel products are readily available through electrical wholesalers everywhere, we can react quickly when service is needed."
The lifespan for the plant is forecast at between 30 and 40 years, and it is expected to produce a total income of 3.3 to 4.5 million euros from electricity.
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