Interconnection of solar home systems as a path to bottom-up electrification

Student thesis: Doctoral Thesis

Abstract

Solar Home Systems (SHSs) have revolutionised electricity access for off grid communities, but have a number of significant limitations. They have limited demand diversity, produce excess energy and lack a clear pathway to scale alongside growing energy demand. Electrical interconnection of existing installed SHSs to create minigrids could offer a way to both scale up energy demand and make use of wasted energy. This bottom-up approach has the potential to be flexible to the changing needs of communities, by using SHSs as a starting point for wider electrification, rather than the end goal. Despite this potential, little analytical work has been undertaken to model SHS interconnection, particularly accounting for demand diversity and long-term system performance. This thesis presents a time sequential stochastic model of interconnected SHSs, to investigate these systems under multi-year operational timescales at high temporal resolution. It is shown for case study systems based on real SHS topologies that there exists significant demand diversity, with small clusters of 20 houses with identical appliances exhibiting an average peak demand of less than 70% of the combined worst-case peak for individual SHSs. Excess generated energy is shown to be an average of 100 Wh a day for the smaller system types and 1000Wh a day for larger systems. Interconnection of these systems demonstrates a significant reductions in LCOE for all system types compared to islanded operation, through more optimal dispatch of battery storage assets and use of excess energy. This resulted in a final LCOE of {dollar}0.63/kWh for a network of 12 large SHSs - a reduction of 48.12% compared to islanded operation and an LCOE {dollar}0.703/kWh for a network of 12 small SHSs - a reduction of 55.23% compared to islanded operation. This informed an investigation of possible operational business models for a network of SHSs, with three approaches proposed - an Energy System Operator with direct control over all users' systems, an Aggregator model, where the system operator facilitates an energy market and a Peer-to-Peer model with direct consumer to consumer energy trading. This thesis provides a robust evidence base for SHS interconnection - demonstrating that the approach can lower cost of energy and facilitate demand growth for off grid energy consumers and proposes appropriate business models to deliver this affordable and clean energy.
Date of Award28 Sep 2021
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsEPSRC (Engineering and Physical Sciences Research Council)
SupervisorCampbell Booth (Supervisor) & Scott Strachan (Supervisor)

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