Helen Gavin

30 October, 2019

Environmental Change Institute, University of Oxford

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How much self-generated electricity do households with solar photovoltaics consume? How does this affect bills and demand from the Grid?

How much self-generated electricity do households with solar photovoltaics consume? How does this affect bills and demand from the Grid?

Households with PV self-consume 37% of their own electricity, demand 24% less electricity from the grid, and save at least £138 per year from electricity bills alone, finds a study by Eoghan McKenna, Jacqueline Pless and Sarah Darby for the Programme on Integrating Renewable Energy.

Addressing climate change requires a rapid transition to systems that are  sustainable, affordable, and secure. Generating renewable electricity from PV has a very high level of public support and can be major role as a provider of zero carbon electricity.

Understanding how much of their own electricity PV households consume is important for solar investment valuation and policy,  and allows consumers to determine the costs and benefits of installation.

Findings
For a typical UK PV installation (2.9kW) and gross electricity demand of 4,000kWh/yr, the study showed that households with PV would:

  • Self-consume an average of 37% their own electricity generation
  • Demand 24% less electricity from the grid compared to households without PV, and
  • Save £138 per year from electricity bills alone (i.e. not including Feed in Tariff payments): this is approximately twice the UK Government estimated.

In addition:

  • On average, PV households export 55–63% of generated electricity, compared to the 50% assumed by the FiT, and
  • There is a large range in self-consumption, influenced by many factors from socioeconomics to daytime occupancy.

Policy implications

  • PV households reduce demand on the grid. Therefore policy instruments that support households to install PV would yield significant benefits in offsetting future demand pressures and the need for other electricity assets;
  • New financial incentives could be dynamic, targeted to bundled systems (PV+battery), and /or introduce time based rules for electric vehicle charging, for example.
  • Investigating the impacts of ‘enabling technologies’ (e.g. home batteries, electric vehicles) on self-consumption could reveal future advantages of balancing supply and demand on the national grid; and
  • More research is needed to understand the factors influencing self-consumption, and this will allow greater insight and enhanced predictions on usage and economics.

Read more in the policy brief or the journal paper.