North Devon Homes (CP1139)

Energy Storage in Fuel-poor Households – CP1139
Lead agency North Devon Homes Ltd.
Other partners
Project summary

This project will install Tesla Powerwall 2 batteries in all-electric, storage heated properties in North Devon using an Economy 7 tariff type. These homes are at particular risk of fuel poverty due to the higher cost of using electric heating. The project will be the first in the UK to use Tesla Powerwall 2 batteries without solar PV and only charged from the grid.  The aim is to assess cost savings to householders by charging the battery overnight from the mains, using cheaper off-peak rate electricity, and using this stored energy to reduce household daytime peak-rate energy costs. Previous evaluations studied smaller batteries (typically 2kWh), with smaller power outputs (500W-1200W) on homes with solar PV. This study will assess the benefit to high electricity consuming households of the greater battery capacity (13.5kWh) and higher power output (3.6kW or 5kW) of the Tesla Powerwall 2.

North Devon Homes and NEA will identify potential properties to be surveyed for suitability and 8 will be fitted with a battery by SunGift Energy. 3 similar control properties will also be monitored in comparison. The households will be monitored from spring 2018 until January 2019, to determine cost-effectiveness and savings.

Evaluation Methodology

Interviews will be conducted with households to collect patterns of electricity-using behaviour and previous energy expenditure. The Tesla app will be used to monitor the charging and discharging of batteries in the homes, and Tesla will also provide daily performance data. Verv loggers will be fitted to monitor 5 of the batteries every second, and current clamps will also be installed to monitor the energy drawn by the different household circuits. Householders will also be requested to take regular meter readings throughout the project, to determine energy and cost savings. The households will be interviewed about their experiences of using the battery, any cost savings and other changes in a final interview at the end of the monitoring period.

Project Outcomes

  • To determine the costs, savings and overall cost-effectiveness of using battery storage in conjunction with Economy 7 tariffs to reduce daytime energy costs for rural off-gas properties,
  • To determine the proportion of the off-peak electricity import before and after the battery is fitted, whether the Tesla battery can power the household throughout the peak rate period and whether there is potential spare capacity for grid balancing.
  • To identify any other relevant factors and learnings around the use of this technology, and practical limitations (space, household wiring).
  • To therefore identify whether this type of technology warrants further exploration and roll-out as a fuel poverty solution.
Region in which project will be delivered South West
Local Authority areas(s) / key locations in which project will be delivered North Devon District
Details of technologies being trialled (for Technical Innovation Fund only) Tesla Powerwall 2 – Tesla, battery storage system.

13.5kWh capacity, 3.6kW or 5kW output

Funding provided

By NEA By delivery agents
Grant amount requested Match Gap
£71,040 £0 £0

Eligible households assisted

NEA grant with gap funding Match Total
8 (+ 3 controls) 0 8 (+ 3 controls)

Download the final report here

Published on 30-04-2019
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