Customers say they have been left in shock after being told that they'll be hit with a massive hike to their electricity rates next month – with some facing increases of up to 83 per cent.

AGL customer Judy Saunders, from Ashfield in Sydney's Inner West, said she was stunned when she received an email from the power company last week, informing her of the new electricity rates she would be charged from July 1.

"It was 51 per cent more than what I'm paying now – I just couldn't believe it," she told 9news.com.au.

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Saunders said she had been on a single-rate plan for the past 12 months after her family had moved back into their newly renovated home.

From July, her electricity rates will surge from 16.5 cents per kilowatt hour to 24.98, with a credit of 5 cents per kilowatt hour for unused solar energy sent back to the grid.

Saunders acknowledged she had been on a seemingly cheap rate prior to the hike.  

"As the cost of living went up, I started shopping around, and every time I went to one of those comparison websites, the usual response was you are getting it better than anywhere else, stick with what you have got.

"So that's what I did, but now obviously all my good luck has run out."

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