Multi-chemistry battery pack using second life batteries for off-grid systems in developing countries

A team led by Oxford’s Professor David Howey has been working to develop battery technology for off-grid solar energy systems. Using previously discarded lithium-ion batteries, they hope to provide round-the-clock access to affordable power for rural communities in sub-Saharan Africa.

Image of two men working on a battery pack

Access to reliable electric power enables communication, education and economic activities that are a fundamental requirement for the wellbeing of people in the 21st century. In areas with no access to national grid systems, solar micro-grids can offer rural communities a clean and safe way to produce energy locally.

The micro-grids use battery systems to store energy produced by photovoltaic cells, providing electricity to people’s dwellings for charging mobile phones, and powering lights and small electronic equipment. This offers many benefits, including replacing dangerous kerosene lamps with electric lights, offering economic development opportunities via the expansion of local businesses, and creating new jobs in the energy service sector.

Much work has been done to develop the photovoltaics needed to generate the electricity, but the limiting factor in these micro-grid systems is the energy storage technologies available; they are the most expensive and least reliable component.

Under the leadership of Professor Howey, members of the Energy and Power Group in Oxford’s Department of Engineering Science are developing a system that uses lithium-ion battery cells in a second-life application. The aim is to reduce the cost of energy storage systems without compromising performance and reliability. To achieve this, the technology relies on a novel concept of battery control and management.

An important part of the innovation is the modularity of the battery units. This allows individual cells to be replaced when they die, resulting in a robust and maintainable battery pack – ideal for the harsh conditions of sub-Saharan countries. This modularity also means that the user can easily add additional battery units as their energy demand increases.

The work, partially supported by EPSRC and HEFCE funding, is being realised through a strong partnership with INTASAVE – a globally operating not-for-profit organisation who are implementing the provision of solar hubs in selected villages in Kenya.

The ultimate vision is to develop the micro-grid model to an extent where it can outcompete expansions of national power grids. National grids are often hampered by regulatory and financial issues. Even once established, they can be unreliable, expensive and rely heavily on fossil fuels. Micro-grids offer an opportunity to leapfrog outdated fossil fuel technologies, providing a more sustainable and environmentally friendly alternative.

To read more about the work, visit the Howey Research Group's website.