Integration of distributed small-scale photovoltaic and energy storage systems in power networks

  • Javier Lopez Lorente

Student thesis: Doctoral ThesisDoctor of Philosophy


The proliferation of distributed small-scale photovoltaic (PV) systems during the last decade has led to large installed capacities of grid-connected variable renewable energy in distribution networks. This trend is set to continue due to a combination of factors, such as the decreasing cost of technology and the decarbonisation policies governments have committed to deploy for the mitigation of climate change. It is anticipated that small-scale PV systems together with energy storage systems will play an important role towards this transition, both as hybrid solutions of PV coupled with energy storage systems and stand-alone PV with energy storage at grid scale.

Small-scale PV systems are often not monitored nor controlled by system operators. As such, they represent invisible, weather-dependent generation that can produce unpredictable demand -- supply imbalances, alter the requirement for ancillary services and bring about additional challenges that may constrain their integration in power systems. In this regard, this thesis explores the aggregated impact of distributed small-scale PV systems on the activities of power systems related to operation, planning and electricity markets in the context of the Northern Irish power system.

The thesis is divided in two core parts. The first part investigates the aggregated impact of distributed stand-alone PV systems and focuses on estimating the regional aggregated generation and near real-time output monitoring of small-scale PV systems. The estimation of the overall PV generation includes the development of a novel approach using a method with origins in mathematics and computational geometry to account for the spatial variability of solar resource. The monitoring of PV generation explores the use of local weather networks utilising open data from personal weather stations, which can be a complementary data source for land-based irradiance measurements. The second part addresses the aggregated response of PV systems interacting with energy storage systems. It is presented as a techno-economic assessment of the role of energy storage systems covering behind and front-of-the-meter solutions with multiple operational strategies available for these systems. The thesis also identifies the key benefits and limitations for the future deployment of energy storage systems in the context of power system planning.

Overall, the methodological innovations presented in this thesis can assist system operators in the integration of small-scale PV systems and inform policy makers in the role of PV and energy storage systems in favour of more robust, low-carbon and efficient power networks in the future.
Date of AwardJul 2021
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SponsorsINTERREG VA Programme (European Union) & Special EU Programmes Body
SupervisorXueqin Amy Liu (Supervisor), Robert Best (Supervisor) & D John Morrow (Supervisor)


  • Distributed electricity networks
  • distributed generation
  • distributed storage
  • energy storage systems
  • personal weather station
  • photovoltaic system
  • power systems
  • PV system
  • PV upscaling
  • regional PV generation
  • renewable energy source
  • small-scale PV systems
  • solar irradiance
  • solar power
  • solar PV integration

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