The Netherlands Photovoltaics Programme

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by A de Ruiter of the CADDET Dutch National Team

INTRODUCTION

Solar power will be one of the most important sources of sustainable energy in the 21st century. This conviction forms the basis of the Netherlands research and development programme for photovoltaic solar energy ('NOZ-pv'), managed by Novem.

THE FUTURE

The Dutch Ministry of Economic Affairs predicts substantial growth in sustainable energy sources and also believes that photovoltaic solar energy (PV) will be one of the most important sustainable sources. Accordingly, the Ministry earmarked tens of millions of guilders for preparing the large-scale introduction of solar power. This money is to be used to intensify research and development, promote industrial follow-up and support large-scale demonstration projects. The policy is aimed at maintaining the Netherlands' position at the forefront of photovoltaic solar energy. It should also provide a solid foundation for large-scale use of this type of energy after the year 2000 in the solar age.

In the longer term, the best opportunities for photovoltaics in the Netherlands will be in buildings. Integration of PV in roofs and facades of homes and other buildings has
considerable advantages, particularly in a densely populated country like the Netherlands.

HERE AND NOW

To enable large-scale use of PV in urban areas, it is important to gain experience in the market now. For this purpose the learning programme "PV in the Built Environment" has been designed within the framework of the NOZ-pv. Two remarkable examples of large-scale, grid-connected PV-systems in the built environment were demonstrated in the urban areas of 'Nieuwland' and 'Nieuw Sloten'. Both projects yielded valuable experience.

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Installation of the PV-panels in the Nieuwland project

'NIEUWLAND' PROJECT

In the 'Nieuwland' expansion area planned by the municipality of Amersfoort, the REMU electricity company has installed PV systems on 50 rented houses. From the very beginning, the use of solar energy has been an integral part of the design. The layout of the estate was based on the assumption that the houses had to be oriented towards the sun, but did not necessarily have to face south.

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The criterion was that the output of the PV-systems must be at least 95% of the estimated feasible maximum. Studies showed that, provided the angle of pitch of the PV roof was not too great, the roofs could face anywhere from south-east to south-west. This gives sufficient scope for an urban planner to design a highly attractive residential area.

The architectural design shows a pent-roof with a vertical 'step' providing space for windows, which enables the use of passive solar energy. The lower roof area is covered with conventional roofing tiles, while the top area is the energy-producing roof containing solar cells and thermal solar collectors. In this project, frameless PV panels mounted in aluminium profiles constitute the waterproof layer. Shell Solar Energy (former R&S Renewable Energy Systems) has installed a total of 110 kWp of turn-key PV systems on the roofs of 50 rented houses. Through conduits in the cavity wall, the (dc) power is conducted from the panels in the roof to seven small inverter rooms, containing 5 kW dc/ac inverters.

The PV systems will remain the property of the electricity company REMU, which has established legal rights on the houses in this respect. In the rental agreements with the householders, the housing corporation has included provisions allowing REMU access to the houses and obliging the householders to prevent shadow.

Because all the parties involved the municipality, the housing corporation, the architect, the contractor, the supplier and REMU were enthusiastic about the project from the start, it got off to a quick start and proceeded smoothly. The project has already demonstrated that the use of PV on houses is compatible with an attractive estate layout and architecture, and that there is wide public support specifically for the use of PV in the built environment.

A much larger project is being prepared as a follow-up. A total of 1.3 MWp will be installed on about 500 homes, a primary school, school dwellings, a day care centre, a
sports hall and a community centre.

'NIEUW SLOTEN' PROJECT

The Energy Company of Amsterdam, now part of ENW, wished to investigate how PV could best be integrated in part of a new residential area called 'Nieuw Sloten'. An added difficulty in this project is that Amsterdam has to build high-density housing. Apart from south-facing roofs, east and west-facing roofs were also admissible to a limited extent, provided they had a low angle of pitch. The PV systems have been installed on the roofs of 70 homes designed for owner occupation, both low and high-rise. The PV panels have a total capacity of 250 kWp, with Shell Solar Energy supplying 140 kWp and BP Solar 110 kWp. The project is partly financed by the EC THERMIE programme.

The project was aimed at a high level of integration with:

  • the ac electricity grid;
  • urban planning, architecture and the building construction;
  • the usual organisational processes of a house-building project, including contracts involved.

The electricity from the panels is conducted to a separate inverter room via an underground dc network. Surprisingly, detailed calculations showed that the output of the system would be maximised by connecting most of the arrays to a single inverter. The losses due to mismatch would be partially compensated by the greater yield of a large inverter. In addition, a large inverter would be cheaper. On the other hand, the varying orientations of the PV arrays meant that the size of the inverter could be reduced. This aspect will be monitored particularly closely over the next few years. The centralised design will make it easier to manage and maintain the system.

For more information contact the CADDET Dutch National Team in Sittard.

The CADDET Renewable Energy Newsletter is a quarterly magazine published by the CADDET Centre for Renewable Energy at ETSU, UK.

The articles published in the Newsletter reflect the opinions of the authors. They do not necessarily reflect the official view of CADDET.

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