Toda Corp announced Aug 21, 2014, that it has introduced a "direct-current power supply system" into its Institute of Construction Technology in Tsukuba City, Ibaraki Prefecture, Japan.
The system stores direct-current (DC) electricity generated by solar panels in a storage battery and supplies it to LED lamps and mobile phone chargers without converting it to alternating-current (AC) electricity.
Toda developed the system as a technology for "zero-emission buildings" (ZEBs) in collaboration with Tokyo Rectifier Co Ltd. Because the direct-current power supply system eliminates the loss caused by AC-DC conversion, it enables to more effectively use solar electricity and realizes an about 10% higher energy efficiency than existing systems that convert solar electricity to AC electricity. Those existing systems perform DC-AC conversion twice, causing conversion loss each time.
Moreover, with the introduction of the system, it becomes possible to store surplus (solar) electricity during business hours on clear days in the storage battery. And electricity can be supplied from the storage battery to power LED lamps, etc during nighttime hours, when the solar power generation system is not generating power.
To realize ZEBs, Toda aims to establish environmentally-conscious technologies while cooperating with companies from different industries. Considering that the direct-current power supply system will be widely used as a ZEB technology and standardized, the company plans to continue the research in the aim of introducing the technology into office buildings and manufacturing facilities.