WA state-owned power retailer Synergy has posted a financial loss of $656 million.

The company has blamed a “challenging energy landscape” for its woes, after posting losses far greater than the $180 million forecast over three years.

Synergy says the rapid uptake of rooftop solar is partially to blame for the loss.

The flood of renewable energy is undercutting Synergy’s fleet of coal- and gas-fired power plants.

“A number of factors have negatively impacted Synergy's financial performance, including increasing fixed costs, the rapid uptake of intermittent renewable energy, in particular rooftop solar PV, and milder than expected weather conditions affecting our baseload generation,” Synergy CEO Jason Waters said.

There was also a $428.9 million impairment on assets, which the company said was a result of increased fixed costs.

“The impairment can be attributed to changes in our generation operations, long-term power purchase agreements and regulated network charges that are no longer being offset by adequate levels of revenue available through the franchise, contestable and wholesale markets,” Mr Water said.

The CEO claimed the company is committed to renewable energy through its Warradarge Wind Farm and the expansion of the Greenough River Solar Farm.

“Both of these projects will help us in achieving our large-scale renewable energy target obligations, maintain control of system security and reliability and create employment opportunities for the Mid West region of the state during the construction phases,” he said.

It all comes after the McGowan Government announced power prices would rise by just 1.75 per cent (to shield households from rising energy prices) rather than the 7 per cent jump projected in last year's budget.

This decision created a big gap between the price Synergy receives for its electricity and the costs of producing it.