Mini-grid

A mini-grid is an aggregation of electrical loads and one or more energy sources operating as a single system providing electricity and possibly heat, isolated from a main power grid. A modern mini-grid may include renewable- and fossil fuel-based power generation, energy storage, and load control. A mini grid can be fully isolated from the main grid (wide area synchronous grid) or interconnected to it. If it is interconnected to the main grid, it must also be able to isolate (“island”) from the main grid and continue to serve its customers while operating in an island or autonomous mode. Mini-grids are used as a cost-effective solution for electrifying rural communities where a grid connection is challenging in terms of transmission and cost for the end user population density, with mini-grids often used to electrify rural communities of a hundred or more households that are 10 km or more from the main grid. Mini grids and microgrids are similar, and the terms are sometimes used as synonyms. Both microgrids and mini grids include generation and distribution, and generally include electricity storage in the form of electrochemical batteries. Both can “island” in the event of a blackout or other disturbance or – common in mini grids – in the case that they were never connected to the main grid in the first place. In practice, the term “mini grid” is used more in a context common in low- and middle-income countries providing electricity to communities that were previously unelectrified, or sometimes used to provide reliable electricity in areas in which the national grid is present but where electricity is sporadic. Across Sub-Saharan Africa, more than half of households connected to the main grid reported receiving electricity less than half of the time. The African Mini Grid Developers Association (AMDA) reports that uptimes of mini grids of its members for which data was available averaged 99% across countries. In contrast, the term “microgrid” is used more in higher income countries to refer to systems that provide very high levels of reliability (for example, “five nines” or 99.999%) for critical loads like data centers, hospitals, corporate campuses or military bases generally in service areas that already have high levels of reliability (e.g. “three nines” or 99.9% reliability) by global standards.

Background

History The electric grids of many developed, high-income countries once started out as mini-grids. These isolated electrical systems were then connected and integrated into a larger grid. This first generation of mini grids was pivotal to the early development and industrialization of most modern economies, including Brazil, China, Denmark, Italy, the Netherlands, Spain, Sweden, the United Kingdom, and the United States. Mini grid systems introduced in the late nineteenth and early twentieth centuries can be described as the first generation of mini grids. Starting in the 1980s and ramping up through the 1990s and early 2000s, a second generation of mini grids numbering in the tens of thousands was deployed in many low-income countries. These systems are typically small and isolated, powered by diesel or hydropower, and built by local communities or entrepreneurs primarily to provide rural households with access to electricity, especially in areas not yet served by the main grid. Many of these systems were overtaken by the national grids. Some that still exist are now prime candidates for hybridization with solar photovoltaic (PV) systems to reduce the fuel cost.

Contemporary mini grids Over the past few years, a third generation of solar mini grids has emerged. These mini grids, mostly solar PV hybrids, are owned and operated by private companies that leverage transformative technologies and innovative strategies to build portfolios of mini grids instead of one-off projects. The typical third-generation mini grid is ready for interconnection with the main grid, uses batteries for storage, and employs remote management systems and prepay smart meters. This third-generation mini grid also incorporates energy-efficient appliances for productive uses of electricity into its business model. These mini grids operate in more favorable business environments, taking advantage of cost reductions in the latest mini grid component technologies and regulations developed specifically for private-sector investment.

Rural electrification

Many rural communities remain isolated from larger, traditional grids due to geographic and economic constraints. The electrification of the global off-grid rural population remains a major task of many developing and developed countries, and according to the International Energy Agency in the 2013 World Energy Outlook, mini-grids represent the most cost-effective way to provide universal electricity access to these populations. Due to new technology innovations that have resulted in declining costs both for mini-grids and energy generation sources, specifically solar and wind power, mini-grids have the potential to electrify remote areas that would otherwise remain outside of a grid connection. Mini-grids are a cost-effective and timely solution for more isolated areas in which connection to the main electric grid is unavailable, and represent a practical option for meeting the energy demand in Sub-Saharan Africa, South and East Asia, and Small Island Developing States. Millions of people remain without access to electricity today, and the U.N. Sustainable Development Goals commit the global community to provide a solution. The map on the right demonstrates energy disparity between developed countries such as the US, China, and Europe while South America, Africa, and Southeast Asia still have many communities that lack reliable, sustainable, affordable energy. Mini-grids are currently being viewed as one of the most effective solutions to bringing energy to rural populations where the energy demands are such that individual stand-alone systems such as nano-grids are impractical but where the population is large enough to require a larger grid system. Because a grid must balance the supply of energy with the demand, the mini-grid's larger size and flexibility allows for safer and more affordable power.

Technical components

… excerpt ends here. Continue reading the full article.