The 1880s saw the “battle of the currents”, a struggle between the companies of Thomas Edison and George Westinghouse over the dominance between DC and AC electricity distribution. AC electricity won for practical reasons – particularly it was easier to transform voltages. But recent technology developments are based around devices that are naturally DC, such as white-light LEDs, home energy battery storage, photovoltaic generation (PV) and electric vehicles (EV). This has reopened the question of DC vs AC electricity.

We have seen a growing interest in DC technology and infra-structure. In many cases DC offers a more efficient medium of transmission and use than AC, but the equipment to support DC installations is years behind AC. In the residential electricity space, need for DC technology is predominantly driven by the rise of PV panels, resulting from both a change in public opinion on sustainability as well as government policy on feed in tariffs and small scale energy generation. The industrial space also shows signs of renewed interest in DC technology, predominantly driven by cost savings in energy consumption. Many pieces of factory equipment are internally driven by DC and will provide reactionary energy e.g. when braking a motor. Large scale DC electricity buses and associated components such as DC breakers and current sensors are therefore hot topics.

In practice only parts of the grid will go DC. A growing practical issue will be managing mixed systems with some DC.  The challange will be around development of DC metering and safety equipment and also the regulatory environment to support new classes of DC equipment.