The amount of green electricity generated in the Netherlands rose by 8% last year, largely due to increased production of solar power, national statistics office CBS said on Friday.

Last year, 18 billion kilowatt hours of power were generated by wind, sun, biomass and water – enough to supply some 4.5 million households. Green electricity now accounts for 15% of Dutch needs, the CBS said.

Wind turbines still account for more than half of the total but the amount of solar energy soared by over 40% last year as more homes and offices install solar panels, the CBS said. The Netherlands is also home to more solar farms.

Despite the rise in renewable electricity production, the Netherlands is still lagging well below targets for total green energy use.

In 2017, just 6.6% of the energy used in the Netherlands came from sustainable sources, but the target is 14% by 2020.