State-owned electricity utility Eskom is piloting a micro-grid system in a rural Free State town that may offer a solution to electrifying other remote areas, where the cost of connection to the national grid is currently prohibitive, due to a number of factors such as difficult terrain.
The R4.2-million system, which has been deployed by Eskom Research, Testing and Development in Ficksburg, incorporates solar photovoltaic (PV) generation, battery storage and intelligent energy management. These technologies have been integrated into a standard low-voltage reticulation network, where electricity is delivered to consumers through conductor wires in a local distribution network.
Group executive for transmission and acting executive for risk and sustainability Thava Govender describes the modular offering as both reliable and sustainable and believes it can contribute to South Africa meeting its 2025 universal-access target. Likewise, there is potential to offer the system to other African countries, where grid penetration is lower and where access remains below 50%.
Since 1994, Eskom has connected some 6.7-million households to the grid, raising electricity access to above 90%. However, there are still remote communities that are not connected to modern electricity services. “Once proven, Micro-grids could be a key solution to this challenge,” Govender says.
The project is in a pilot testing phase. The future commercial proposition, he adds, will benefit significantly as a result of the sharp decline in solar-PV costs, as well as an improvement in battery costs, which are expected to continue to decline as adoption rates increase globally.
In addition, advances in energy management systems make it possible to balance generation and load across the micro-grid. “In many ways, we are seeing, through the micro-grid, an intersection of the world’s of sustainable development and system operation.”
The pilot project has been tailored to the demand needs of 14 households, but could be augmented should there be any increase in demand.
The solar PV system has a 32 kW peak capacity and the direct-current energy generated is converted, using an inverter, to 220 V alternating current for use by those connected to the micro-grid.
The residual electricity is stored in three sets of lithium-ion batteries, which have a combined capacity of 90 kWh. This stored energy supplies the inverters during cloud-outs and when the sun sets. Based on the anticipated battery life, the system is expected to be operational for 22 years. The operations of the micro-grid are monitored on an ongoing basis from a control room at Eskom Research, Testing and Development’s Rosherville campus, in Johannesburg.
Govender reports that the demonstration project took only months to develop and build and that the design has subsequently been optimised from a cost perspective. A similarly sized micro-grid could now cost in the region of R1.75-million to deploy and the costs could be optimised through partnerships with equipment suppliers.
Nevertheless, affordability remains a challenge, particularly for poor rural communities. In addition, policy certainty and stability will be required before widespread deployment is possible and Eskom is working with the authorities on ways to ensure such certainty.
“However, there is little question that micro-grids are an increasingly compelling proposition for geographically challenging areas that are either difficult to access, or require extensive capital investment to reach,” Govender asserts.