The first week of the implementation of the controversial carbon tax ended with an announcement by the Australian Competition and Consumer Commission (ACCC) that it investigated and sanctioned two solar panel producers.

Polaris Solar and ACT Renewable Energy claimed that the cost of electricity would go up by 400 per cent under the carbon tax. Their warning was found in brochures the two firms sent to households. Initially, the increase would be by 20 per cent on the first year of the carbon tax's implementation, but if the increases go on, by 2019, the hike would reach more than 400 per cent, the two firms claimed.

The federal government which started to collect the $23 per tonne carbon price on Sunday, July 1, estimated rise in electricity prices due to the carbon tax by only 10 per cent and will increase yearly at smaller rates.

ACCC acting Chairman Michael Schaper said the two companies fully cooperated with the regulator and promised not to repeat their offence. As part of the solar firms' penalty, its directors were mandated to attend a course on consumer law.

"If a business claims that a potential price rise is linked to the carbon price, the claim must be truthful and have a reasonable basis," Mr Schaper reminded Aussie firms.

Within the same week the ACCC caught bakery chain, Brumby's, encouraging outlets to increase their prices and blame it on the carbon tax. Like the two solar companies, Brumby's was caught because of its advice to stores in the company's printed internal newsletter. Brumby's has apologised for the gaffe.

Although the ACCC has authority to impose fines of up to $1.1 million on erring firms that attribute hefty price increases to the carbon tax without a clear basis, the regulator said it did not slap the penalty yet on the bakery nor the two solar power companies.

"We're not hitting them heavily, as no consumers suffered any financial loss. Two consumers contacted us but neither had suffered a loss and the firm was fully cooperative," Smart Company quoted Mr Schaper.

However, while the ACCC is empowered to run after such firms that make false claims about the impact of the carbon tax on Australians, it could not sanction the Coalition which has been running a scare campaign against the levy.