Mercury Energy's earnings have fallen on the back of weaker renewable electricity generation, and its bottom-line profit has taken a hit.

The company's profit has plunged from $290 million to just $1 million, due to tough power generation conditions.

Despite this, Mercury Energy CEO Stew Hamilton is hopeful ahead of another financial year.

"We're investing heavily in new power plants - we're investing about $1 billion in new power plants at the moment. That's from the top of the north to the bottom of the south."

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