The firm revealed it made around £45 a year from each of the estimated 23,000 customers affected by mis-selling and expected to pay them compensation of between £65 and £70.
SSE, the energy supplier fined £10.5 million for mis-selling earlier this month, expects to pay out about £1.5 million in compensation, it has told MPs.
SSE - one of eight suppliers questioned by the Energy and Climate Change Committee - promised to compensate any customer who had lost money.
After the hearing, an SSE spokeswoman said the £60 to £75 figures were "typical" at the moment but affected customers were being treated on a case-by-case basis, adding: "We will make right any financial loss."
SSE's deputy chief executive, Alistair Phillips-Davies, said the company had changed its training and audit procedures to correct the problem, adding: "As soon as we knew there was mis-selling, we took action."
He admitted that the company's actions had affected trust among consumers, saying: "I would have thought for some customers, it would have decreased the level of trust. Although for others, it would not."
He said some feedback from customers suggested they were pleased with how the company had handled the issue. He also revealed SSE had agreed to accept the £10.5 million fine from regulator Ofgem, who found that the company had been guilty of "prolonged and extensive" mis-selling.
MPs also repeatedly pressed suppliers EDF and E.On to "come clean" about their own practices.
Jim Poole, director of residential customers at EDF, said he was confident that the company's controls were robust enough to ensure there was no widespread mis-selling.