Solar curtailment vs. storage

Swiss researchers have looked at whether storage could be cheaper than curtailment in medium-voltage distribution networks with significant amounts of PV capacity. They considered storage costs, operational costs, grid constraints, electricity costs, PV generation models, and loads.

Cost comparison of energy models, with PV curtailment and without it

Image: EPFL, Applied Energy, Creative Commons License CC BY 4.0

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From pv magazine Global

Researchers in Switzerland have developed a new methodology for energy storage siting and sizing, in response to the curtailment of PV generation and grid constraints. They aim to determine whether curtailment could be cheaper than energy storage in medium-voltage distribution networks with distributed-generation PV capacity.

The used a linearised power flow model instead of traditional non-linear AC optimal power flow models.

“We use a linearised power flow model because it can be applied to distribution grids with both radial and meshed configurations, as opposed to second-order cone relaxations that are typically valid for radial systems,” they explained.

They considered storage costs, operational costs, grid constraints, electricity costs, PV generation models, and loads. They also assumed that energy storage provides active and reactive power compensation in the event of overproduction from PV.

They found that the viability of storage systems and their sizing are strictly dependent on electricity prices, which can be influenced by higher or lower levels of PV generation. The scientists concluded that curtailment is cheaper than installing batteries.

“A sensitivity analysis showed that decreasing costs of energy storage technologies could make installing energy storage cost-competitive compared to curtailing PV generation,” they said.

They presented their findings in “Optimal sizing and siting of energy storage systems considering curtailable photovoltaic generation in power distribution networks,” which was recently published in Applied Energy. The research group includes scientists from the École polytechnique fédérale de Lausanne (EPFL) and Switzerland’s Institute of Sustainable Energy.

“Studying sizing and siting of energy storage systems, in combination with curtailment of PV generation for satisfying the grid constraints stands as the main contribution of this paper,” they concluded.

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