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2. Installations Description
2.1 Ustra in Hannover :
The PV field is integrated on the new-built Leinhausen Depot of the Üstra company of public transports at Hannover. The Hannover's plant has benefited of development realised in Geneva in the choice of components, security systems and monitoring. So the concept of Hannover is the same than this of Geneva. (fig.5)
2.1.1 Photovoltaic modules :
230 kWp (1615 modules of monocrystalline silicium) are integrated on the roof of the building. This PV field is composed of 8 long sheds of about 80 and 100 meters long, and 3 little ones on the central part of the building. These fields are oriented at 35° from south direction (toward West). Five of the long sheds are coupled with light dwells intended for hall ligthning on their nordern face. The PV collectors of these sheds are tilted by 20°. The other sheds are placed lower on the roof, and tilted at 10° only.
A complementary field of about 19 kWp is placed on the south facade. This part was primarily foreseen with amorphus modules. But the evaluation of the offers revealed that there are no suitable technologies on the market, meeting the demands for :
- Voltage stability,
- Building integration and
- Efficiency guarantees over the service life.
Therefore this part was also equipped with crystalline-Si cells modules.
The contract considers the application of the following modules as creating the photovoltaic generator (table 1)
2.1.2 Combination with Magnetic Dynamic Accumulators :
Magnetic dynamic accumulators will be installed in the Hannover LRT system to intermediately store recovered braking energy until an approaching train can use it. They can also be used for the intermediate storage of solar power generated by the PV plant which is not being utilised.
A test installation at another location on the LRT network (Fasanenkrug terminus) confirmed the proper functioning of the system. The operating behaviour of the magnetic-dynamic accumulator used in the test will however require some optimisation of the technical layout.
Magnetic-dynamic accumulators are also planned for the Leinhausen Depot. It is specified with the power characteristics 3,3 MW / 9,2 kWh at a charge / discharge cycle of 30 seconds up to several minutes The construction provision required has already been undertaken. According to üstra's installation plans for their magnetic-dynamic accumulators, they will not be available in Leinhausen at the same time of commissioning the PV plant. This has no direct relevance in this context because they are not part of the project.
|Module Type ||Manufacturer ||Cell/Module Type ||Module Power (Wp) ||Number of Modules ||Generator-Power (kWp)
|Insulation Glass Modules
||Siemens SM 103
||MST 43 L
Table 1: Hannover photovoltaic modules
2.2 TPG - Geneva :
The Geneva plant is also located on the roof of the Public transport Depot. Nevertheless the metallic roof was already built about five years ago, and the PV field had to be disposed in sheds on dedicated supports, with strong requirements about the weight and the waterproofness. Therefore, an unusual flat tilt of 5° (minimum necessary to the water flow and dirt removal) was chosen, leading to about 8% irradiation decrease by respect to optimal tilt of 30°. Nevertheless this allowed to drastically reduce the weight and costs of the supports.
The field is made up of 1'400 mono-crystalline modules of 110 Wp each, i.e. 70 strings of 20 modules in series. In order to match the nominal line voltage of about 640V, the optimal number of modules in series was found using the PVSYST software, which is able to simulate such a DC-grid installation.
2.3 TCL - Lausanne :
Beyond the Geneva part of the Swiss contribution, three little installations have been implemented in Lausanne, these are :
2.3.1 Perrelet plant, 19 kWp installed as a sun-shield on the top of the city Bus Depot. These are 396 modules Photowatt PWX500T, tilted about 20° in south direction. For a nominal line voltage of 660VDC (+30%/-20%), 44 modules are connected in 9 series strings.
2.3.2 Riponne plant, 10.7 kWp of the same module type, as sun-shields for shop windows. Orientation is comparable to the precedent, but standing against a facade. The number of modules in series is here 45 per string.
2.3.3 Rhodanie plant, 14.4 kWp of "Powerwall laminates" 240 Wp modules disposed on a south façade.
These three plants will start working at beginning of march, 2000. Security concept of these installations is undertaken by Lausanne.