5) Is DC system design an academic pursuit or are manufacturers exploring DC as a part of their product lines?
Many of your home appliances utilize DC – the majority being electronic based. For high voltage grid applications, the larger manufacturers such as ABB, GE-Alstom, Siemens, and Mitsubishi have built high voltage direct current (HVDC) systems since the 1970s. For medium voltage DC applications (about 1 kVdc to 35 kVdc), product development in DC is being pursued because of the push for a larger penetration of renewable energy resources into utility grids. Photovoltaic and wind turbine systems utilize DC in their conversion path or directly output DC. Grid energy storage, like small batteries for appliances, output DC voltage and current and is necessary for integrating photovoltaic systems due to their intermittent outputs. For lower voltage DC applications (380 Vdc to 1 kVdc), data centers and telecommunication equipment is considering the use of DC for powering these system components.