Department of Economic Development

The main environmental factors, i.e. sunlight incident angle, spectrum, solar radiation, shade, and Photovoltaic module temperature, shall affect the efficiency of solar cell system. That implies features of abundant solar radiation, avoiding architecture shade from the east, west and south directions are necessary for site selection. In addition, there exist other influence factors, e.g. dust, bird excrement, erosion chemicals, architecture stiffness, appliance conditions. The roof top and south-facing tilt roof of buildings excluding the shading influence can be regarded as ideal installation sites. Consequently, the installation sites of photovoltaic systems shall avoid the shade from the adjacent buildings, the PV module should face south, and the tilt angle shall be around 22-25±10 degrees.

The unit of Photovoltaic system capacity is peak watt, also known as kWp. 1 kWp Photovoltaic system capacity is defined as 1kW electricity output under 1,000 W per square meter and air-mass 1.5 spectrum solar radiation. In present the average installation space of 1 kWp capacity is 10-15 square meters, however different types of solar cell will demand specific space, e.g. mono-crystalline silicon will need 7-9 square meters installation space and silicon thin film solar cell will need 16-20 square meters installation space. In Taipei, 1 kWp solar system capacity can generate 2.5 kilowatt hour, totally 900 kilowatt hour per year. In central and southern Taiwan, such capacity can generate 3.5 kilowatt hour, totally 1,300 kilowatt hour per year.