The blackout that plunged South Australia into darkness in September cost the state $367 million, a peak business body has revealed.
Business SA says a survey of 200 of its members showed an average $120,000 was lost each minute in trading and production costs and wages.
On average, companies lost $5000 while the lights were out. However more than half of those surveyed suffered no losses.
Business SA says the figures would have been worse if the power had gone out at the start of the trading day rather than after 4pm, but it was still a high price to pay.
"The blackout dealt a real body blow to the state's economy at a time when it least needed it," Business SA's Anthony Penney said in a statement.
Mr Penney said the organisation was concerned about the potential for more power load shedding incidents over the summer and had asked the government to assure "everything will be done" to prevent further disruptions.
The power went out on September 28 when SA was lashed by severe thunderstorms which brought down major transmissions lines in the state's north.
A number of wind farms switched off as a safety precaution and the interconnector with Victoria shutdown.
The lights were back on in Adelaide within a few hours but the process took longer in rural areas, including up to three days on the Eyre Peninsula.
Business SA said businesses on the Eyre Peninsula lost on average $10,000 from the incident, bringing the total loss for the area to $8 million.