General information Location: Tokyo Building of NTT Do Co Mo, Tokyo, Japan Sunshine hours (yearly average): 4,96 hours per day Type of project: Office Building & Electric wave relay base of mobile telephone Type of application: BIPV Time for design process: Schematic: One month Final drawings: One month Construction documents: Two months Time for construction: Project started 1998, completion September 2000 BIPV installation: 5 months Realization: September 2000 [ Top ] Description In this building planned as a base of the communication of information on NTT DoCoMo(NTT Mobile Communications Network Inc.), the company has positively accepted a project designed with attention to environmental issues. As a result, the first design proposal was changed, in order to include a PV system on the south wall of the building. In order to harmonize the PV to the overall design of the building and to reduce the cost of the installation it was necessary to improve the mounting technology to hang the modules, and to modify their profile. Given the morphology of the building, particular attention was given to problem such partial shading or exceptional length of wires to avoid potential decreasing of power. The electric power is grid-connected but it also used as emergency backup power supply to the telecommunications equipment. [ Top ] System characteristics PV system power: 11 kW utility-interactive with standby capability Type of building integration: Wall integration (BIPV Wall) Type of cell technology: Poly-crystalline silicon cell (Cell colour: Gray), Manufacturer: Daido Hoxan Inc. Coloured grey poly-crystalline silicon cells were adopted in consideration of the harmony of the image of the building stone wall within the city skyline. Moreover, some dummy cells were arranged in the outer part of the module to avoid adverse effect of shading. Module dimensions: H 888 × W 1940, 48 pieces, 123 watts and H 1348 × W 1940, 28 pieces, 184 watts, Manufacturer: Showa Shell Sekiyu K.K. Inverter: Central inverter of 10 000 watts, Manufacturer: NTT POWER AND BUILDING FACILITIES INC. [ Top ] Project cost breakdown Because it was installation to the facade of the highrised building, PV module installation construction and wiring work were divided by every 2-3 floors, and it was connected with the cost rise. [ Top ] Performance characteristics Electricity generated: 4 600 kWh (Estimation for one year, start-up October 2000) System availability: 78 % max. power, October 2000: 8,6 kW Incidents or Outages: none [ Top ] Project team Client: NTT Mobile Communications Network Inc. 2-11-1 Sanno park tower Nagata-cho Chiyoda-ku Tokyo (Mobile telephone and communication company) Project architects: NTT Power and Building Facilities Inc 3-4-1 Guran park tower Shibaura Minato-ku Tokyo Design: NTT Power and Building Facilities Inc. Engineers: KAJIMA CORPORATION, 1-2-7 Moto-akasaka Minato-ku Tokyo General Contractor: KAJIMA CORPORATION PV electrical design and installation: KAJIMA CORPORATION Structural Support for PV: NIKKEI URBAN BUILD PV manufacture: Air Water Inc. & Showa Shell Sekiyu Inc. [ Top ]