Elon Musk's Tesla will be sourcing outside investors to help fund the $800 million virtual power plant to be built in Adelaide, with the South Australian Premier Jay Weatherill saying the value in the project is so "profound" the United States company will have no shortage of takers.

The virtual power plant, billed as the largest of its type in the world, will have 250MW of output if the full complement of 50,000 households being supplied with free solar batteries and Tesla Powerwall 2 home storage batteries is reached in four years, under the plan unveiled on Sunday. That is equal to about 20 per cent of the state's total average daily power needs.