In response to the soaring demand, the government imposed a cap of 150 megawatts for the scheme, but the actual cost rose to $180 million after the cap was breached by 15 megawatts. Energy Minister Peter Collier told ABC radio this morning that although there had been a cost blowout, the extra costs had not been incurred as a result of the scheme running a month longer than it should have. "The blowout in terms of funding was not because we took a month to close the scheme," he said. "The notion that the blowout is a result of the extra month is abject nonsense and scare mongering. "The vast majority of that comes from the 13,000 extra applications that came through from budget time until the end of June."

Mr Collier said the problem had been inaccurate information and a breakdown in communication between Synergy and the Office of Energy. He had been wrongly told the scheme was approaching the half-way mark of around 70 megawatts close to budget time in May last year. "The information we received was blatantly wrong", he said. "I can only go on the information I was provided." In reality the figure was much higher and less than two months later he was informed the scheme was nearing the cap of 150 megawatts, which was subsequently reached in late June.

Mr Collier defended the decision to allow the scheme continue running for a further month until August 1. "We decided to hold off (on closing the scheme) until we had the most forensic figures available," he said. By this stage applications had slowed down, he said, with the cost blowout resulting from applications launched before June. There had been "a disconnect between the Office of Energy and Synergy," Mr Collier said, with Synergy providing data for the number of solar installations, which the Office of Energy actually thought was application data. Mr Collier admitted the breakdown in communication needed to be addressed.

"We're not impressed, and we need more rigour in the offices," he said. Despite the blowout Mr Collier insisted the scheme was not a failure, citing the popularity of the scheme, which saw 76,000 households signing up and stimulating the solar industry. Shadow Energy Minister Bill Johnston said the blowout reflected the chaos Mr Collier had brought to the portfolio and said he needed to take responsibility for his performance. He said it was alarming the Energy Department knew the cap had been reached and spent time discussing how to end the scheme with his department. "Peter Collier knew as early as June 8 that the cap had been reached, what was going on in his mind?" Mr Johnston asked.

"This is a complete failure of administration by the minister; all these issues come back to his desk." Mr Johnston said Mr Collier's statements to the media overlooked several elements, including the incorrect processing applications. Before the cap had been reached, 5,000 people had applied for the benefit but had been recorded as "zero value" and had not been taken into account for calculations, he said. Mistakes such as these meant the cap had probably been reached in May, three months before the scheme finished, but the department did not realise it, Mr Johnston said. "He [Mr Collier] says the outcome was good anyway because all these people have got solar panels, but how many people would have had solar panels at a lower cost to government?" he said.

"Clearly there was a better way to encourage people to get solar panels." Mr Johnston said it was the latest example of mismanagement, pointing to a 680 per cent increase in complaints to Synergy and the overhaul of the energy provider's billing system, which had cost $93.4 million since its introduction in 2009, when the original budget was set at $38.5 million. "The shambles of a billing system that he [he Mr Collier] said was fabulous," Mr Johnston said. "I asked him to show any statistics that show improvement with Synergy and he couldn't do it." Follow WAtoday on Twitter @WAtoday