Reporter: A three-storey reinforced concrete residential renovation, by the way in the flat roof installed capacity of 4 kilowatts of solar panels. Panels are mounted on the panel, with a 30 degree angle of inclination towards the south and fixed horizontally. It is estimated that the annual electricity generation should reach about 4,000 kWh, which is equivalent to 70% of the electricity consumption of the house. However, after about six months after setting, the actual power generation was found to be 30% less than the predicted value. The owner of the complaint designer should bear the responsibility. So, what is the reason? The shadow of railings and other blocks blocked the battery Flat roof set on the solar panel. The use of slotted steel and other formed platform, in order to achieve the maximum annual electricity generation, toward the direction of the south at a 30 degree tilt angle installation. On the south side of the solar panel, there are railing and the like for preventing falling, blocking the part of the panel due to the shading generated, resulting in a significant decrease in power generation. Panel arranged on the surface of the 10 cm to 15 cm square between the units are mostly in series. Therefore, even if only one unit reduces the power generation, it will have a greater impact. Therefore, the installation of the battery board need to pay attention to select the direction to prevent the shadow of the battery cover, or even if the battery board is shadowed, but also to minimize the impact of control. Japan's solar panel shipments in 2012 were 2.7 times the previous year, reaching 3.8 million kilowatts, setting a record high. The fixed price acquisition system for renewable energy power generation started in July 2012 is the main reason for the surge in the installed capacity of solar power generation equipment. With the rapid expansion of solar power equipment settings, disputes are also increasing, architectural designers were involved in the situation is not uncommon. For the above-mentioned problem homes, the designer did not accurately understand the characteristics of solar panels. The designer sets up the rack of the battery in 2 lines. Near the south side of the panel set in front of a drop for the railings, shading the shadow of the panels. Also, the shadow of the front panel blocks the rear panel. However, the designers made the wrong judgment, saying: "The shadow area that blocks the panel is very small, and there is no problem even if the power generation is reduced." Even a small shadow can lead to the entire panel annihilating, solar panels may not be reduced and power generation is proportional to the shadow area. Ordinary crystalline silicon solar panels use a structure that uses a wire called an interconnector to connect the "cells" of the power generating elements in series. If the unit is replaced by a dry cell, it is easier to understand the current flow path. Many solar panels In order to prevent such "annihilation", a component called a bypass diode is set up to divide the cells in the panel into three systems. Its working principle is, bypassing the existence of non-power generation unit of the system, circulation current, thereby reducing the overall power generation panel to reduce the minimum. The amount of electricity generated by a solar panel is determined by the maximum product of voltage and current. The reduction in power generation is not only affected by the amount of solar radiation and the temperature of the solar panel but also by the direction in which shades are formed. For example, if the shadow is enlarged in the direction of the cells in series. Even though up to 18 cells are shaded, only one of the three systems generates electricity, so the total power generation is reduced by only 33%. On the other hand, if the shadows expand in the orthogonal direction, even if only 5 units are shaded, all systems will be affected, resulting in a sudden drop in power generation. In principle, solar panels need to be placed in a shadowless place. In the last resort, you need to pay attention to the design orientation when installing the panel, in order to achieve even shadow shading, but also to reduce the power generation to a minimum.