Low-cost Photovoltaic Power for a Swiss Bank
by O. Humm, Switzerland
A standardised photovoltaics plant generating 100 kW peak output has been developed for the Union Bank of Switzerland. The plant, on the roof of the Bank's new headquarters, generates electricity at the lowest-ever price for photovoltaics in Switzerland.
Solar-generated electricity, produced by the standardised photovoltaics plant on the roof of the Bank's "Suglio" building in Manno near Lugano, Switzerland, costs an amazing CHF 0.80/kWh, less than CHF 10,000/kW installed (where CHF is the Swiss franc). The generating costs were obtained from a detailed study taking building and operating costs into account. Even at this low price, photovoltaics cannot yet compete with normal power stations. However, the project emphasises that photovoltaic prices are now on the move; the price is now a factor of two lower than a few years ago.
From 1997, three installations will be operating at the Suglio building:
·the roof-mounted installation mentioned above with a peak output of 102 kW;
Total costs are CHF 1.8 million, of which CHF 1 million is for the roof-mounted installation. Investment for the facade-mounted and sun-shade system designs is higher in comparison, because satisfactory integration into the building is more difficult. The energy cost calculation is based on the yield and costs of the optimised 100 kW standard roof-mounted plant.
The roof-mounted installation consists of 1,196 monocrystalline solar cell modules of type BP 585 L, with a peak output of 85 W per module. They were installed in 1996, and are mounted on 2,400 concrete stands of type SOFREL N95 which are made in Switzerland. The plant includes two inverters with a total output of 80 kW, and measuring and control devices.
Table: Breakdown of Net Investment for the Components of the Photovoltaic Installation
The promoters and owners of the photovoltaic installation decided in favour of the BP 585 L cells, as these gave the lowest price for the complete plant. However, this depended on each individual system fulfilling minimum criteria.
In the 1980s, a team at the University of New South Wales developed a modified version of the conventional monocrystalline solar cell. They laid the visible circuitry ie the external metallic conductors in laser-cut channels. Rotated at right angles to the surface, these conductors take up less of the sunshine. Measurements carried out at Cannobio Technical College show an efficiency of 16.2% for the cells and 13.2% for the modules. This type of cell was selected for the Suglio project.
Since the photovoltaic cells come from abroad, Swiss specialists have no direct influence on their
manufacture, but supporting structures and module interconnections are different. In recent years, considerable progress has been made, and in the Suglio project, the SOFREL supporting system
and the multi-contact connecting system finally broke the CHF 10,000/kW barrier.
Photovoltaic power prices have been greatly reduced through the Suglio project's well-designed
building and operating schemes and quality-assured installation. This success is expected to stimulate investment and lead to a continued fall in the price of photovoltaic power. For more information contact the
For more information contact theCADDET Swiss National Team in Aarau
The CADDET Renewable Energy Newsletter is a quarterly magazine published by the CADDET Centre for Renewable Energy at ETSU, UK.