How solar home systems temporally stimulate increasing power demands in rural households of Sub-Saharan Africa

Small solar home systems (SHS) have emerged as potential alternatives to grid electrifications, enabling households to make modest investments into their power systems, and to modify those systems according to their changing economic circumstances and power demands. Study shows that introduction to basic electricity access temporally stimulates increasing power demands in rural households, leading to eventual installations of larger systems that can power more electric appliances. Specifically, study shows that once households get access to basic electricity, they get to realise the socio-economic benefits of it and start to desire more appliances, with TV being the most desired appliance, followed by stereo systems, small fridges, and small cooling fans. These desires are realised temporally with increasing household incomes, leading to increasing loads, and thus to the modifications of the originally installed small SHS, to meet those increasing load demands; the desire for luxurious appliances leads to activities that contribute to increased household incomes, and thus to the modifications of the initial SHS. Acquisitions of luxury appliances lead to improvements in quality of life and to improved esteem visibility and social status within the local communities. Potentially, increasing load demands within a given community could lead to extensions of the national utility grid to those areas, as total loads justify such investments. SHS therefore potentially act as grid electrification stimulators, leading to eventual grid electrification of a given community

Frontier citizenship and state fragility in Kenya

Insecurity is a major problem amongst the nomadic communities in North western Kenya.  The communities include the Pokots, Turkana, Marakwet, Toposa and Karamoja.  Using the Pokot Community as a case study of nomadic life style, this paper examines the environmental constraints, cattle rustling and small arms as triggers of Pokot community movements into their frontiers; -zones of contact of states or communities.  In search of water and pasture, the Pokot traverse their frontiers and interact socially, economically and environmentally with their neighbours.  The movements expose their cattle and property to banditry and cattle rustling.  The Pokots thus acquire small arms to protect their livestock and property even though the acquisition of and stocking of arms is the responsibility of the government. So the acquirement of small arms by the Pokot creates a fragile insecurity situation characterised by cattle rustling and banditry.  As Kenyan citizens, the Pokots have a social contract with the state to provide security but this is not the case because of the transitional nature, as nomads.  Insecurity to the nomadic communities manifests in terms of environmental, natural resource based and identity based conflicts. It is concluded that addressing insecurity in this region has to lessen banditry, cattle rustling, social underdevelopment and negative ethnicity.  The steps towards solving state fragility and insecurity ought to take cognizance of the interactions between frontier citizens, environmental constraints, traditions, politics and acquisition of small arms. Key words: security, frontier, cattle rustling, democrac

Droop control methods for PV-based mini grids with different line resistances and impedances

Different droop control methods for PV-based communal grid networks (minigrids and microgrids) with different line resistances (R) and impedances (X) are modelled and simulated in MATLAB to determine the most efficient control method for a given network. Results show that active power-frequency (P-f) droop control method is the most efficient for low voltage transmission networks with low X/R ratios while reactive power-voltage (Q-V) droop control method is the most efficient for systems with high X/R ratios. For systems with complex line resistances and impedances, i.e. near unity X/R ratios, P-f or Q-V droop methods cannot individually efficiently regulate line voltage and frequency. For such systems, P-Q-f droop control method, where both active and reactive power could be used to control PCC voltage via shunt-connected inverters, is determined to be the most efficient control method. Results also show that shunt-connection of inverters leads to improved power flow control of interconnected communal grids by allowing feeder voltage regulation, load reactive power support, reactive power management between feeders, and improved overall system performance against dynamic disturbances

Different storage-focused PV-based mini-grid architectures for rural developing communities

Impacts of grid architectures on temporal diffusion of PV-based communal grids (community owned minigrids or microgrids) in a rural developing community are modelled and simulated using MATLAB/Simulink and a survey-informed agent-based model (ABM) developed in NetLogo. Results show that decentralised control architectures stimulate minigrid formations and connections by allowing easy expansions of the minigrids as each decentralised PV system within a minigrid is treated equally and determines its own real and reactive power, eliminating the need for communication links. This also reduces the cost of implementing such a system; fewer connections are realized with centralised controls as such systems require high speed communication links which make them both difficult to expand and expensive to implement. Results also show that multi-master operation modes lead to more communal grid connections compared to single-master operation modes because in the former, all distributed PV systems within a communal grid have the same rank and can act as masters or can be operated as combinations of master generators (VSIs) and PQ inverters, allowing for more design flexibility and easy connections from potential customers

Modelling Temporal Diffusion of PV Microgeneration Systems in a Rural Developing Community

An agent-based model (ABM) is developed in Netlogo as a tool for evaluating temporal diffusion of PV-based communal grids in a rural developing community. ABMs model individual entities within a complex system and the rules that govern the interactions of the entities within the system, to capture the overall effect of such interactions. Results show that given various choices, small PV mircogeneration systems would emerge as the prefered source of electrification for many households. Also, with increasing power demands, many household would prefer communal grids to the national utility grid. Furthermore, introduction of favourable government policies in the form of subsidies and mircocredit facilities, coupled with increasing social acceptance, would lead to increased PV installations and correspondingly to increased communal grid connections. Specifically, introduction of a subsidy of $0.15/kWh would result in an increase of 249% in communal grid connections. Increasing the sensing radius from 1 km to 2 km would result in an increase of 118% in communal grid connections

Modelling Impacts of Socio-Economic Factors on Temporal Diffusion of PV-Based Communal Grids

Impacts of socio-economic factors on temporal diffusions of solar electricity microgeneration systems in a rural developing community are modelled and simulated using an agent-based model (ABM). ABMs seek to capture the overall macro-effects of different micro-decisions in a virtual world; they model individual entities within a complex system and the rules that govern them to capture the overall effects of their interactions. Results showed that falling PV costs coupled with generally increasing grid electricity costs would lead to increased uptake of PV systems in such communities. On the other hand, high lending rates in most developing nations would stifle use of credit facilities in purchases of PV systems and thus diminishing their uptakes. Results also showed that introduction of favourable government policies in forms of subsidies would strongly stimulate PV installations in such communities. Social acceptance is important for diffusion of any new technology into a given market and more so with solar systems; results show that neighbourhood influence plays major roles in PV diffusions with many households installing PV systems if their neighbours within a given sensing radius do the same. Results also showed that requiring a certain percentage of neighbours to have installed PV before a household considered doing the same could have negative effects on PV installations as decisions to install PV are influenced by many independent and dependent factors and not by neighbourhood threshold alone

A comparison of DC- versus AC-based minigrids for cost-effective electrification of rural developing communities

Sub-Saharan Africa continues to suffer energy poverty due to low grid expansion rates necessitated by low economic activities in those regions, sparse population distribution coupled with low household load demands, and insufficient power generation. On the other hand, small solar power microgeneration systems have emerged as potential alternatives to grid electrifications, enabling households to make modest investments into their power systems, and to modify those systems according to their changing economic and power demand circumstances. For rural social-economic development, electricity-beyond-lighting is needed. Without the grid, the only alternative is minigrids based on locally available renewable energy resources. In this work, we compare the merits and demerits of DC and AC coupled systems as pertains to costs, efficiencies, and overall performances. Research shows that power conversion stages are the biggest points of power losses in minigrids and therefore avoiding many conversion stages lead to improved overall system efficiencies. Research also shows that the best performances are realized when DC-inherent appliances are supplied with power from DC-coupled networks, supplied by distributed DC power generators such as PV. Simulation results show that when given choices, consumers choose to connect to DC networks with decentralized storage due to lowest operating costs, ease of expansion, and overall better performances when compared to other networks