Speaking to Utility Week, he said: “It’s easy to overlook the scaling that becomes available with mass deployment. If just 5 per cent of Britain’s 30 million customers buy a Powerwall (7 kWh), that’s a total of 10.5 GWh of storage, which is equivalent to the 9 GWh Dinorwig pumped storage station in North Wales.”
“That is serious storage capacity for the British system, and could be attractive from a national perspective provided that it can be harnessed to the benefit of the householder and the power system,” he added.
Scott also warned that it was important to consider a “whole-system perspective” to avoid “unwelcome and costly” outcomes of mass scale of distributed devices, which could create “really powerful storage opportunities”.
“For example, if the 5 per cent of households I mentioned before all had time-of-use tariffs that saw a national low price for energy and instructed their home storage to start charging, it could create a 3 GW load step that would shut down the national grid,” he said.
When Tesla unveiled its rechargeable lithium-ion energy-storing battery, Powerwall, last week, professor of energy policy at Exeter University Catherine Mitchell described the potential for competitive energy storage as “another nail in the coffin of conventional utilities”.
The battery, available in a 7 kWh and 10 kWh form, is designed to collect and store excess energy from roof-mounted solar panels and small-scale wind turbines. The company claims the technology will “wean the world off fossil fuels”.
Deliveries of the batteries will begin in the US in late summer and Tesla says there are plans for the technology to be available in the UK before for the end of the year, “with more details to follow”.
Uptake in the US has been significant, with Tesla announcing that the devices are sold out until mid-2016, after the company received 38,000 orders.
Mott MacDonald group strategic development manager Simon Harrison told Utility Week the impact of the technology would “initially be quite small”, on grounds of cost and the types of tariff that typical domestic users have in the UK. However, over time energy suppliers “may start to look at deals where customers install them”.