solar power taxable ?

There has been conflicting reports in the various medias about solar power electricity that is being generated and fed back into the grid, ie. whether it is taxable or not ?
The reports are mainly saying that it is.
Is the total value of power generated taxable or the amount in excess of household use taxable ?
I phoned the Taxation Dept., but they couldn't give me a definite answer without me sending a letter to the Tax. Commissioner requesting info on this subject.
The female that I spoke to said that generally, if it is only a residential home, there should be no tax on electricity generated.
I suppose if you were only generating a couple of thousand dollars worth of electricity p.a., even if you were a pensioner, it should not affect your tax liabilty or pension.

Is there anyone knowledgeable on this topic, as even the solar companies appear not to know the facts concerning this consideration before committing to spending maybe tens of thousands of dollars going solar and taking years to recoup your money and then get the benefit of free electricity.

Thanks, Ravi