Communities which reside in rural areas far from existing electrical infrastructure constitute a significant portion of the 600-million people in sub-Saharan African who have no access to electricity. These communities are deprived of modern lifestyle improving technologies such as electric light, microwave cooking, radio and television, cellphones and internet access – things most people take for granted.
In some far-flung villages, a single LED lamp and a cellphone charging point are offered to address this problem. These services are generally powered by a single PV panel on the person’s home (Fig. 1). These limited services, however, offer no real life-improving benefits.
To provide an electrical service to rural communities which will offer the benefits of modern life, a PV-powered microgrid with a decent amount of battery backup and inverters is needed. This equipment will provide a 220 V AC supply equivalent to what urban dwellers receive from Eskom or their municipalities, thereby enabling people living in rural villages to access the internet, watch TV, cook in a microwave oven, use a computer, charge their cellphones and install as many lights as they want to.
Over and above the convenience offered by these modern devices is the safety aspect. Electric cooking removes the need for open fires, candles and paraffin stoves; external lighting improves safety and security; while access to radio, TV and the internet provides people with access to information and education. These benefits result in the upliftment of an entire community.
The Smart Grid Centre of Excellence at Eskom’s Research, Testing and Development (RT&D) centre based at Rosherville, Germiston, has been testing and comparing PV panels and batteries for a number of years. The organisation designed and built a microgrid at its own premises which has been undergoing tests for some time. However, to get a proper understanding of the way in which the equipment will operate in a real-life setting, the power utility decided to build a test site in a rural village.
The power utility built a pilot solar-powered microgrid at Wilhelmina Farm‚ Ficksburg‚ in the Free State. Wilhelmina Farm, an agricultural primary co-operative in what is said to the cherry capital of the world, was chosen as the selected site for the test project. The area, which nestles in the mountains bordering Lesotho, is said to have a solar resource of between 4,5 and 6,5 kW/m2.
The system comprises 120 PV panels, with a generating capacity of 32 kWp, a 90 kWh Li-ion battery and a set of inverters which convert the DC from the panels and the battery into 220 V AC. The equipment is housed in two shipping containers. The AC is distributed to the village’s 14 households by overhead aerial bundled cable.
To manage the loads dynamically, each house is wired via a distribution board which splits the loads into essential and non-essential services. Refrigeration and lighting are deemed to be essential, while power outlets for irons, kettles, toasters, etc., are considered to be non-essential.
Should the village’s load increase beyond predetermined thresholds, non-essential items can be turned off remotely, without interrupting electricity to lights and refrigerators. This test site is not connected to the electricity transmission grid. The batteries are charged by the PV panels.
In the event of a prolonged period of cloudy weather, resulting in the depletion of the batteries, electricity can be supplied by two 22 kW diesel generators. According to Renier de Lange, an engineer involved in the design and construction of the project, the PV panels provide sufficient energy to recharge the batteries in about four hours, while supplying electricity to the village at the same time. The project includes solar powered street lights which operate independently.
The houses have been fitted with roof-mounted solar hot water geysers, so electrical power is not used to heat water. However, the 81 families who reside in the village have sufficient electrical power to enable the use of refrigerators, irons, TVs, satellite decoders, and other domestic appliances.
The microgrid is totally independent. However, information from the site is relayed by means of a radio communication system to the nearest substation and sent from there via power communications to Eskom’s RT&D centre.
In this way, all aspects of the installation at the site are monitored, including solar resource, battery state-of-charge, load information, etc.
On Friday, 2 November 2018, Eskom officially launched the project. Wilhelmina Farm falls under the jurisdiction of the Setsoto Local Municipality which incorporates the towns of Ficksburg, Clocolan, Marquard and Senekal.
In her speech, the executive mayor, Cllr Nthateng Maoke, said that although Wilhelmina Farm gets some support and assistance from the municipality, Eskom’s microgrid project is a real blessing, giving new hope to the community.
The electrification of small villages is one of the municipality’s goals, she said, and the community was grateful for the microgrid project and for the work it has created for some local residents during its two-month construction period.
Three women, representing the community, expressed their heartfelt gratitude for the electrification of the village, saying that the project had changed their lives forever. They said they were blessed to have electricity and that they were amazed at the engineers’ ability to turn sunlight into electricity.
Eskom’s Nick Singh said that the project symbolises innovation‚ growth and development and is consistent with the power utility’s future strategic objectives as microgrids incorporating renewable and smart energy technologies will play an important role in the electricity industry of the future.
The project is a partnership between the Department of Agriculture‚ Forestry and Fisheries the community of Wilhelmina Farm and Eskom’s Smart Grid Centre of Excellence.
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Source: EE plublishers