West Australian consumers could face huge power price hikes in the coming years unless the State Government starts to factor in the exponential growth of renewable energy, a new study has found.

The uptake of rooftop solar in WA has grown at a rate of almost 20 per cent in recent years as households have moved to reduce their power prices.

That in turn has upset the state's electricity market, which is heavily tied to fossil fuels.

Report author Bill Grace from the University of Western Australia said the nation's energy regulator — the Australian Energy Market Operator (AEMO) — had greatly underestimated the future uptake of renewable energy.

He said that would result in higher power prices for consumers.

"With the current scenario, over the next 20 years we're talking about significant increases in tariffs — 50 per cent perhaps," Professor Grace said.

"To try and protect this legacy, coal-fired generation units will just keep prices high, and will also waste power people have purchased solar panels to produce.

"As there is more private solar produced, the network has to generate less electricity, but because a lot of the costs in the system are fixed, the unit cost — that is the cost per unit of energy — can only rise."

Demand on the SWIS will be increasingly affected by solar energy exports, according to Professor Grace's modelling. ( Supplied: William Grace )

WA's South West Interconnected system (SWIS) — which provides power as far north as Kalbarri and as far south as Bremer Bay — is fuelled largely by a mixture of gas and coal, providing much-needed baseload power for periods when the sun is not shining.

Since 2010, the amount of solar power produced on the SWIS network has grown to 650 megawatts, and Professor Grace predicted it could rise to 9,000 MW by 2035.

He said that scenario made baseload power almost redundant.

"The impact will be felt by about 2025, when there will be so much solar energy being exported from private houses that it will start to impact on the generation on the network, particularly coal-fired generation or baseload power," he said.

"The private solar from houses and businesses exported onto that network effectively reduces the demand below the level that baseload coal can operate."

Regulator's modelling flawed: professor

AEMO oversaw the electricity market in Western Australia and makes predictions about future power demands on the network.

There are concerns power tariffs in WA could rise by 50 per cent in the next 20 years. ( ABC News: Andrew O'Connor )

Its modelling predicts rooftop solar energy will grow at a linear rate, meaning the market will grow at the same amount each time step.

However, Professor Grace said that modelling was flawed because the market was growing at an exponential rate — with uptake doubling in each successive period.

He said AEMO modelling of linear growth in solar uptake inadequately assessed the growth in demand, and in turn the amount of solar and storage that would be on the grid and the impact it would have on the conventional generation network.

"So one of two things can happen. Either the coal-fired power generation is switched off or alternatively, the private solar will have to be switched off," he said.

This scenario was realised by the California Independent System Operator (CAISO) in 2013 in their analysis of the impact of solar on network generation.

California now produces around 20 per cent of its power from renewable sources.

CAISO analysis identified the risk of overgeneration, when more electricity is supplied than needed to satisfy real-time electricity requirements.

Minister Nahan dismisses concerns

The State Government said it trusted the AEMO projections and advice regarding future power demands in WA.

"AEMO is the trusted authority on providing forecasting and security advice as it draws information from a range of experts, including industry and governments, and I have total confidence in its advice," Energy Minister Mike Nahan said.

"The latest Australian Energy Market Commission report confirms West Australians continue to pay among the lowest in Australia for electricity."

The AEMO was contacted by the ABC about Professor Grace's report and said everyone was entitled to their opinion, but declined to comment any further.