Innovative Low Voltage Single Wire Earth Return (SWER) for Affordable Microgrid Distribution Infrastructure in Africa

A typical village in rural Uganda might have 225 houses, consume an average of 0.3kWh per day from a minigrid, and require 8km of distribution infrastructure (poles and cables) to connect all the spread out houses. The village in the UK in which we are based has 1250 houses, consuming (conservatively) 10kWh a day, and requiring just 4km of (identical) distribution infrastructure because of our high housing density. Our electricity tariffs are roughly the same (at $0.20/kWh).

The UK village pays a combined total of just over $900k a year for electricity, which repays the cost of the distribution system within 2 weeks. The households in Uganda pay just under $5000 a year for electricity usage, and will therefore need more than 16-years to repay just the cost of the poles and cables, without even factoring in the cost of the electricity generation itself.

More than anything else, it is the cost of distribution that kills the commercial viability of minigrids, and prevents remote households from being connected to electricity systems in offgrid rural communities in Africa. There has been little to no innovation in distribution to match the significant recent advances in generation and storage technologies and affordability.

Single Wire Earth Return is a promising technology used for high voltage rural connections in the electricity grid in the US, Canada, South Africa, Mozambique, Laos, Brazil, Australia and New Zealand. In this feasibility study we propose to adapt the technology to low voltage (230V) use in last mile connectivity in rural minigrids and test its performance in multiple locations and climate/soil conditions, collecting data to demonstrate its cost effectiveness and safety for users and the community in rural energy access.

We estimate the technology could save as much as 70% of the cost of traditional distribution systems.

We will also engage with local regulators and the international energy access community to introduce them to this technology, and encourage its uptake to enable wider energy access in remote communities and households, and lower energy tariffs in these communities.

Partners SVRG (\>20 innovative rural energy systems in sub-Saharan Africa), MOSCET (foremost sustainable energy company and minigrid installed in Lesotho), Kiima Foods and OMASI (rural development NGOs with experience of \>40 community technology solutions) and electrical engineering experts National University of Lesotho Energy Research Centre are collaborating on this project to trial the technology in three communities and evaluate safety and cost-benefit.