When Julia Gillard and Hillary Clinton announced they wanted to ''make solar power competitive with conventional power sources'' within five years, they left out one important detail.

Their goal was based on solar being competitive with coal-fired power after a carbon price had been imposed.

When you think about it this is obvious - if solar power could provide electricity as cheaply as coal-fired power without putting a cost on the emissions from coal, then we wouldn't need to impose that cost. The problem would be solved. We could forget the whole carbon price thing, because the only reason to have one is to give a leg-up to more expensive, low-emission sources of power.

But according to the executive director of the Australian Solar Institute, Mark Twidell - who will be managing the $50 million the federal government has stumped up for the initiative - cost-competitive solar without a carbon price sounds too good to be true because it is too good to be true.

Carbon Price | Solar Power Deal With US