The launch of a new battery for homes that can store solar power for use in the evenings is "another nail in the coffin of conventional utilities", it has been claimed.
Tesla announced it was launching the wall-mounted lithium ion rechargeable storage units, based on the batteries used in the company's electric vehicles, at an event in California.
Chief executive Elon Musk said: "Our goal here is to fundamentally change the way the world uses energy", as he launched the new "powerwall" batteries, which are little bigger than a conventional boiler.
The technology will cost between $3,000-$3,500 (£2,000-£2,300) and will start shipping in the US in the summer.
It is being marketed as a home battery which charges using electricity from solar panels or when energy prices are low, and powers the home in the evening as well protecting against power cuts.
It "offers independence from the utility grid and the security of an emergency backup", the company said.
A number of companies are trying to develop energy storage systems which will be able to store the power generated by intermittent renewables such as solar, to allow widespread use of clean energy while ensuring reliable supplies.
In the UK, green power company Ecotricity is launching a pilot later this year in 100 homes for its "black box" energy storage system, while Moixa Technology has received funding from the Department of Energy and Climate Change for its battery-based units for people's homes.
Catherine Mitchell, professor of energy policy at the University of Exeter: "The potential for competitive energy storage, whether household or utility scale, is another nail in the coffin of conventional utilities.
"Those countries, like Denmark and Germany, with a reasonable proportion of variable power such as wind or solar have seen fossil fuels being displaced from the electricity market and have seen peak energy prices fall, leading to falling profits and share prices of conventional utilities like E.ON, RWE, Vattenfall and ENEL.
"Storage offers the ability to extend both the displacement of fossil fuels and reduction of prices beyond peaks - making it even worse for companies whose business models are based on fossil fuels and peak pricing profits," Mitchell added.