Authorities are cracking down after a spike in solar panel-related house fires in NSW.

NSW Fire and Rescue has extinguished 30 blazes believed to be sparked by panels in the past 3 months, an increase of about 20 per cent on last year.

Fire and Rescue NSW says that most of the time, the fires “remain within the switch”.

“But we have had instances where they spread to the house.”

Fair Trading NSW has been sent out to spot-check over 100 businesses, which has led to 20 solar panel operators being fined for failing to meet industry standards.

Minister for Better Regulation Kevin Anderson says people must do their research before having the panels installed.

“There are some unscrupulous tradespeople out there who are selling less than the best quality products ... not installing them properly and causing fires,” he told reporters.

He urged people to check the Fair Trading website to see if their installer is licenced.