Research & Innovation Services

Project Edison SmartDC – DC local network in the University Library

KTA Partnership Development Award

Centre for Sustainable Power Distribution, Department of Electronic & Electrical Engineering, RWE npower and Western Power Distribution
Prof Raj Aggarwal and Dr Mike Redfern 

“Bear in mind that computers, communications and entertainment equipment, and LED lighting, are run from DC. And that batteries and solar panels operate using DC. For many domestic and business applications, in terms of managing power consumption, DC is a much more efficient way to run a local power network than using AC.”
Professor Raj Aggarwal, Director of the Centre for Sustainable Power Distribution, University of Bath

“The KTA project has given npower and the University of Bath an excellent framework for exchanging knowledge that we have developed, either independently or jointly. The KT framework enables us to develop those ideas together, in confidence.”
Jacob Allinson, Electrical Engineer, RWE npower

“Customer energy demands are continually changing and this can have a big influence on the way network systems operate. We’re taking the ideas demonstrated at Bath in Project Edison and rolling them out on a much larger area because we believe this will change the way we run our networks in the future.”

Chris Harris, Head of Retail Regulation, RWE npower


Electronic equipment such as computers, TVs and telecommunication systems run on direct current (DC), but being supplied with mains alternating current (AC) each device normally requires an AC/DC converter.  Energy and cost savings can be made if a single, central AC/DC converter can supply many DC devices.  In addition, such DC networks offer enhanced flexibility. Back up power supply batteries can be charged using low-cost electricity, or powered by renewable energy (RWE) devices such as wind turbines and solar panels. Batteries or RWE devices can then supply DC power at times of peak electricity demand (when commercial tariffs are high) or should the mains power supply fail. DC systems therefore have the potential to offer energy-saving, cost and environmental benefits, along with enhanced security of supply.


Given the power industry’s moves towards greater integration of renewable energy sources with conventional sources of power generation, there is growing interest in developing local DC networks that could operate flexibly and efficiently alongside AC networks (so-called ‘hybrid systems’).  With such networks in mind, Bath researchers working initially with RWE npower staff and then joined by Western Power Distribution as a partner for Stage 2, explored the potential benefits of running University of Bath Library computers on DC rather than AC supply.  In stage 1, a 6-month trial, with 50 modified computers and their monitors powered from a specially created DC network, tested the feasibility and potential benefits of the DC approach.  The success of the initial project resulted in a follow up (Stage 2) award. DC-powered LED lighting was incorporated into the network, Smart control was introduced together with monitoring and experimental testing, the charging/discharging characteristics of a battery array were explored, and the dynamic properties of integrating solar panels were tested.  Project Edison evaluated the potential for operating a local DC network on the equivalent of a light industrial scale so that findings and recommendations could inform innovative and influential follow on projects on a larger scale.

Benefits and outcomes

  • In testing over 18 months, the new DC network and its associated PCs consumed about 30% less electrical power than the AC-powered PCs they replaced.
  • Students reported a positive user experience, with the new PCs being quieter, more compact and with brighter LED backlit screens.
  • The DC network, with a single central AC/DC converter, dramatically reduced the harmonic distortion propagated back into the AC mains supply, thus offering the potential to reduce power supply surcharges associated with such propagation.
  • The LED lights incorporated in Stage 2 produced better quality illumination while consuming 25% less energy than the lighting they replaced, with potential for further reduction with dimming.
  • Stage 2 confirmed that there are opportunities for smart managing the AC mains supply, by drawing on DC battery power during high-cost times of the day, recharging the batteries using AC mains power at lower-cost, off-peak times, and employing solar panels to supplement power supplies and energy storage during daylight hours.
  • The findings from Project Edison are strongly influencing Project So La BRISTOL, a £2.2 million initiative funded by the Low Carbon Network Fund, which involves the three Project Edison partners collaborating with Bristol City Council. Project So La BRISTOL is creating a SmartDC network system linked to batteries and solar panels for 30 homes, 10 schools and a large commercial building. Its findings are likely to have far-reaching effects on the commercial operation of, and statutory requirements for, local power networks in the coming decades.

KTA team

Professor Raj Aggarwal, Project Leader, Department of Electronic & Electrical Engineering
Dr Miles Redfern, Co-investigator, Department of Electronic & Electrical Engineering
Ben Williamson, KT Fellow (Stage 1), Department of Electronic & Electrical Engineering
Surendra Kaushik, KT Fellow (Stage 2), Department of Electronic & Electrical Engineering
Jacob Allinson, Electrical Engineer, RWE npower
Clive Janssen, Commercial Strategy Development Manager, RWE npower
Chris Harris, Head of Retail Regulation, RWE npower
Philip Bale, Innovation and Low Carbon Network Engineer, Western Power Distribution

Funded by the University of Bath’s EPSRC Knowledge Transfer Account, RWE npower and Western Power Distribution.