SOLAR power systems are being installed by businesses at triple the rate they were a year ago as a glut of Chinese cells and rising Australian power prices combine to improve solar’s economics and threaten the profits of coal and gas-fired power providers.

Many of the photovoltaic cell systems used by businesses — which mostly need power during the day when solar cells work best — are being installed without major subsidies, the relative economics have improved so much.

The number of commercial solar installations (or those larger than 10 kilowatts) increased from 550 in the first four months of last year to 1460 in the first third of this year, according to AGL figures. A spokesperson from the Mark Group said the average payback period on a commercial solar system was between four and seven years.