The operating income of A-share listed companies in China's power industry in the second quarter increased 4.47 percent year-on-year, the lowest quarterly increase for the past five years, the Security Times reported on Friday.

According to the newly released half-year results, the listed companies had an operating income of 136.7 billion yuan ($21.5 billion) in total. The growth rate of electricity consumption dropped to 4.3 percent, highlighting China's economic slowdown, though better than the situation in 2008.

In terms of net profit, the power industry earned 7.63 billion yuan in the second quarter, representing a year-on-year growth of 13.4 percent, a bigger increase than the growth in operating income.

However, electricity consumption figures are not indicating a warming up of the country's macroeconomic situation. In April, the growth rate of consumption dropped to 3.7 percent, the lowest ever figure since June 2009.

Usually, the operating income growth rate in the power industry is much higher than the electricity consumption growth rate. However, the growth rate in operating income in the second quarter was close to the consumption growth rate.

Though the National Development and Reform Commission raised the feed-in tariff for power companies at the end of 2011, operating incomes didn't grow significantly this year.

The power industry serves as a barometer of the health of the national economy. The national GDP growth rate was below 8 percent in the second quarter, the first time that happened since the second quarter in 2009.