Alex Chak Lau then 50, was sentenced in the NSW District Court last year to 10 years in prison with a non-parole period of six years and six months.

But the Court of Criminal Appeal on Friday found that Judge Sharron Norton made several errors and omissions in her summary of events, and did not properly account for the objective seriousness of some charges.

The man from Bluff Point on the NSW Central Coast will now spend at least 11 years and three months in jail, and a total term of 15 years for his attacks on eight children.

He had pleaded guilty to 18 charges including sexual intercourse with a child, indecent assault, aggravated breaking and entering, and detaining a person with intent for the crimes between 2008 and 2016.

Over the eight-year period Lau would have young children sleep over at his house, or would drive them home ensuring they were alone in the car.

Lau broke into a young boy's house in 2011 while he was grounded and home alone after school.

"What the f***? What are you doing in my house?" the boy yelled at him before pushing his chest and asking him to leave.

On another occasion the child had fallen asleep in his lounge room while playing video games when he awoke to Lau sitting beside him on the floor.

The CCA found the sentencing judge made an error in not finding the fact Lau had broken into the victim's home to assault him an aggravating factor.

Lau also stated multiple times to the boy that there was "something wrong with him" and this was insolent, Justice Geoffrey Bellew stated in his remarks upon re-sentencing him.

"It also serves as an unequivocal indication that the respondent was motivated purely by self-interest," Justice Bellew said.

"And a wanton desire for his own sexual gratification, irrespective of the harm which might have been inflicted on his victims as a consequence."

Lau will first be eligible for parole in February 2031.

Australian Associated Press