Battery storage for post-incentive PV uptake?: A financial and life cycle carbon assessment of a non-domestic building

Therapid growth of photovoltaic (PV) installations in recent years has largely beendriven by government incentive schemes that make PV an attractive option forbuilding owners seeking to reduce their greenhouse gas emissions and energycosts. As government incentives are reduced or withdrawn the incorporation ofbattery storage, to lower building electricity grid imports through increasedon-site PV self-consumption, is an option to sustain rooftop PV uptake. Thisstudy combines a life cycle assessment approach and discounted cash flowanalysis to assess the CO₂ and financial impact of adding battery storageto a PV assemblage in the context of future incentive withdrawal, electricitysystem decarbonisation and changing technology costs. An example non-domesticbuilding in the UK with a 20kW mono-crystalline silicon PV and 20kWhlithium-ion battery is modelled. With electricity grid decarbonisation in linewith the Paris Climate Change Agreement, the PV and battery system reduces thebuilding’s CO₂ emissions by 15% (18tCO₂) compared withthe grid-only reference over a 30year lifetime. The analysis also highlightsthat battery storage operated only to increase self-consumption of gridconnected rooftop PV does not necessarily increase C0₂ savings ofthe building with wider grid decarbonisation. For the 7%/annum technology costreduction rate examined, adding battery storage to a building’s PVconfiguration negatively affects financial performance for systems installed in2020. PV systems without batteries in the UK are however found to be viable in2020 without government incentives. The study concludes that battery costs haveto fall considerably, or additional revenue from providing electricity systemservices is needed to make batteries financially attractive in lower insolationareas like the UK. Policy to reduce electricity system CO₂ through buildingintegrated battery uptake requires better understanding of the net system CO₂impact in line with other changes in electricity generation and demand.