Photovoltaic systems cause electric shock accidents. Accidents have been reported wherein a firefighter who has extinguished a fire in a solar power generation facility has received an electrical shock. Additionally, there is a risk of electrical shock when touching a photovoltaic module scattered by wind. Specifically, rapid shutdown is popular in the USA to prevent electrical shock accidents during firefighting activities. When rapid shutdown is activated, the photovoltaic system enters a low voltage state. However, this rapid shutdown can only prevent electrical shock accidents during firefighting activities. Furthermore, to introduce rapid shutdown in established photovoltaic systems, the power conditioner may have to be replaced. Therefore, in this study, we propose a system that uses an electromagnetic relay to prevent electrical shock accidents and scattering of photovoltaic modules in photovoltaic systems, caused by fire extinguishing activities. The proposed system can be easily introduced into installed photovoltaic systems.