One of the chief arguments against rooftop solar panels - that households which do not have the systems subsidise those that do - has been undermined by State-owned energy provider Synergy.
In previously secret analysis prepared last year for Energy Minister Mike Nahan, Synergy found customers without solar panels were only $3 a year worse off as a result of the technology's uptake in WA.
Conversely, Synergy concluded households with solar panels were significantly better off.
Those who signed up for the Barnett Government's feed-in tariff scheme, which paid them 40cents for every unit of electricity their systems pumped into the grid, on average enjoyed a $565 "net benefit" a year.
For those customers who missed out on the scheme, which started in August 2010 but was axed a year later amid increasing costs, there was still an $81-a-year net benefit.
Apart from direct payments for their panels' excess capacity, households benefited from generating their own electricity and avoiding the costs of having to buy it from the network.
The analysis, obtained by the Opposition under Freedom of Information laws, casts new light on claims by critics of solar panels that they amount to a massive wealth transfer from households which do not have them to those that do.
However, the analysis said the cost to customers without rooftop solar would keep increasing.
This was because Synergy would be forced to lift the price of electricity to cover its costs as more and more customers put solar systems on their roofs.
The argument has fed into a push to shake up electricity tariffs so all customers, including those with solar panels, pay more for the upkeep of the grid.
As part of the State Budget released in May, Dr Nahan revealed the Government would review tariffs with a view towards charging people more for the right to connect to it.
Shadow energy minister Bill Johnston said the figures discredited one of the main arguments against solar panels.
He said that it highlighted the benefits the panels offered consumers.
"These documents show there is some small cross-subsidy which could very easily be resolved but clearly it shows people getting solar panels should not feel guilty," he said.