Rooftop solar PV could reduce grid resilience, study finds

The study from the University of Nottingham indicates that grid-tied small-scale renewables could cause power failures.

The study drawing on smart meter data from approximately 5,000 households in and around London finds that while a grid with many small-scale generators should be more robust than if using one power source, in reality with the generators operating at different times the grid doesn’t reach optimum levels for the resilience to be achieved leaving it susceptible to failures.

Domestic renewable energy generation is growing rapidly in the UK, with just over one million small-scale solar PV systems installed.

However, this supply of power is unpredictable with generators coming on and off-line intermittently and households adopting the role of consumers or producers as daily and seasonal usage and meteorological conditions vary. Without new control strategies, these fluctuations are found to put the grid at risk of system failures.

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The increasing proliferation of small, intermittent renewable power sources is causing a rapid change in the structure and composition of the power grid,” explains Oliver Smith, researcher in the School of Mathematical Science at the University of Nottingham who led the study.

“Using data from smart meters in UK households we tracked how grid composition varies over time. We then used a dynamical model to assess how these changes impact the resilience of power grids to catastrophic failures. We found that resilience varies over the course of a day and that a high uptake of solar panels can leave the grid more susceptible to failure.”

Specifically, the study addressed the resilience of renewables dominated microgrids with the analysis showing that they tend to operate in the least favourable regions of the robustness landscape, dominated either by consumption or generation.

Battery storage is a natural candidate for smoothing the supply-demand balance. However, while the installation of home battery storage increases the self-sufficiency of the consumer, it does little to ameliorate the resilience problem as these batteries are not designed to dispatch energy back upstream into the network, the researchers find.

The researchers recommend that the supply of power from these batteries should be scheduled to also optimise for power grid resilience.

They also note that nascent technologies such as vehicle-to-grid show promise for balancing renewable power systems and can be used with energy management control systems as virtual power plants.

“It is vital that any such future control schemes also take into account the dynamical properties of the network to ensure the resilience of future power grids,” they say.