Relevance of the field of application
Stand-alone grids serve to secure the power supply in areas that are not or no longer connected to a supra-regional power grid - whether for reasons of self-sufficiency and sustainability or because grid expansion would be unprofitable. Such "off-grid supplies" play a comparatively minor role in Germany, although their relevance is also increasing here.
Globally, the importance of island grids is many times greater: around 770 million people still have no direct access to electricity, 75 % of them in sub-Saharan Africa away from central interconnected grids. Yet electrical energy is seen as a central basis for economic development. According to estimates, access to electricity is likely to have declined in 2020 for the first time since 2013 as a result of the Corona crisis.1
The existing island grids have recently been increasingly converted from fossil (mainly diesel) to renewable energy sources (solar and wind, but also small hydropower plants and biogas plants), for both ecological and economic reasons. In any case, renewable energies play the main role in the realisation of new off-grid projects.
Battery storage systems are particularly important in regenerative island grids based on solar and wind energy: they ensure the balance between fluctuating power generation determined by environmental conditions on the one hand and consumption on the other. In addition, they also ensure the reliability of the island grid and provide system services, such as balancing power to compensate for short-term supply or demand surpluses.
1 International Energy Agency (IEA) (2021): SDG7: Data and Projections – Access to electricity.
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