For a south oriented, roof mounted c-silicon PV generator and a grid infeed limit of 70 % of the rated PV power the curtailment losses are about 2.5 %. In this paper we present a simulation study based on comprehensive measurement data sets from the ZSW test field Widderstall to estimate the influence of grid infeed limits, orientation of the PV generator, domestic self-consumption and battery storage on the energy yield of a PV system. Eventually, mitigation scenarios are discussed considering different points of view like Scotland’s renewable energy targets or limiting factors like capital costs. Then, both solutions are compared considering capital costs, yearly incomes generated, implementation features, reimbursement periods and other characteristics. Its capital costs are estimated at £20.9 million. The pumped hydro energy storage is designed with a 13 MW pump absorbing up to 202 MWh which addresses curtailment issues and a 15 MW hydro-turbine generating up to 183 MWh. It addresses curtailment issues and enables an additional wind capacity of 6.4 MW to be installed in Orkney. Its capital cost is estimated at £ 38.4 million. The grid improvement requires interconnection upgrades and an additional export cable.
Inquiring about mitigation measures, two different scenarios are selected according to grid services and other key characteristics: a grid reinforcement and a PHES implementation. Orkney’s 2019 curtailment rate is assessed as 63.3 GWh which results in 35% of Orkney’s 2019 electricity production from renewables. Such a wind capacity on Orkney’s weak grid often results in grid congestion and consequently, on wind capacity being curtailed. The amount of wind renewable installed capacity in Orkney’s archipelago has reached 57.1 MW in early 2021. With higher PV deployment and a minimal amount of home battery capacity (1.5 kWh/kWp), a 70% share of consumed renewable energy is realized, with a curtailment of less than 20%. It is possible to reach a share of consumed renewable electricity of almost 50% with a curtailment of 9% without the use of batteries.
A realistic and effective deployment scenario for renewable electricity from wind and PV is developed (up to 9 GW wind and 50 GWp PV for the Belgian case). With increasing total PV deployment, the optimal power injection limit is reduced. Above a certain level, additional battery capacity has no effect. The share of renewable electricity consumption is calculated, investigating the impact of battery sizing and different levels for the power injection limit.
A simple algorithm for grid injection limitation of this curtailment during daytime and nighttime is proposed, with and without the use of batteries. The model considers the problem of potential overloads on the low voltage grid, by limiting with curtailment the total PV injection on the low voltage grid to a level that can be currently sustained. The model is balancing the electricity generation of these renewable sources on an hourly basis with the historical consumption profiles of 2014, 2015, and 2016 to estimate how much renewable energy can be consumed directly. An overall model and scenario for increasing the share of renewable electricity consumption in the Belgium grid is proposed by simulating different PV and home battery capacities.
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