The number of solar hot water systems installed in Australia has topped the one million mark, according to the Clean Energy Regulator, but the rate of installation is at its lowest in a decade.

The CER said in a statement on Friday that the one-millionth system was installed in Weston, New South Wales and demonstrates the “continuing strong interest from households to participate in the small-scale renewable energy scheme and enjoy the financial and environmental benefits that come along with that.”\

But the data also shows that the rate of installations has slowed rapidly. So far in 2016, some 33,000 systems have been installed, suggesting that the country is heading for its lowest total since 2006, when nearly 36,000 were installed.

The peak years, as this table below shows, were in 2009, with nearly 200,000 installations, and 2010 and 2011, with more than 100,000.

More than 258 000 solar hot water systems have been installed in New South Wales, making it the state with the largest uptake in the country, but closely followed by Queensland and Victoria.

“An average household can use around 25 per cent of its total energy on heating water and so solar water heaters are an excellent way to reduce energy bills,” said Mark Williamson, executive general manager at the Clean Energy Regulator.

More than 2.5 million small-scale systems have been installed across Australia since the scheme began in 2001. In total, these installations now have the capacity to generate or displace approximately 9.5 million megawatt hours of electricity each year, enough to power more than 1.4 million average Australian homes.