The economic and environmental implications of post feed-in tariff PV on constrained low voltage networks

Abstract

With the recent removal of the solar PV feed-in tariff on ≤4 kWp arrays, installation of domestic rooftop PV has become significantly less commercially feasible in the UK. Whilst alternative trading schemes are beginning to emerge, the adequacy of their return on investment is questionable. However, the extent to which installation may need to be subsidised has not yet been quantified. Furthermore, the extent to which increased peer-to-peer trading could contribute to network constraints, and the environmental and economic costs of managing such schemes, have not been examined extensively. In this paper, the subsidy required to encourage a rooftop PV uptake rate of 0.5% homeowners/year is determined and the costs of constraint management are calculated for various network topologies. The problems presented are solved using time series analysis, power flow simulations, and optimisation processes with Monte Carlo methods. It was found that P2P trading is the most promising post subsidy revenue stream, reducing the required feed-in tariff from £0.14 to £0.10 for systems installed in 2020. Furthermore, it was found that with P2P trading, requirement for feed-in tariff support should end by 2032. Reconductoring was the most economically effective constraint management strategy, costing £50 k to £200 k less than curtailment when applied to 29 networks over 30 years. From an environmental perspective, it was found that reconductoring had a carbon footprint 2 orders of magnitude lower than curtailment & battery storage.