The power generation industry could be forced to mothball capacity because of sustained low wholesale electricity prices, slack demand and rising renewable energy supplies.

The warning, at a public forum on Tuesday, comes as wholesale power prices are at their lowest in several years.

Rising retail power prices have choked off demand, along with the idling of manufacturing and the strong Australian dollar.

Demand in the national electricity market remains soft, with continued incursions by solar and wind energy, Origin Energy's group manager, commercial, analysis and risk services, Phil Moody, told an Independent Pricing and Regulatory Tribunal forum on power prices on Tuesday.