I have been following the Straits Times reports on climate change and I have read about the heat island effect that highly urban cities such as Singapore experience.

Singapore will be getting hotter and hotter in the future and it is now trendy to install rooftop solar panels in private landed estates (Saving the environment one rooftop at a time with solar energy, April 22).

But I have read that this will in fact worsen the heat island effect.

There was a Forum letter published last year that explained why rooftop solar panels are in fact counter-effective (Rethink large-scale solar installations, Sept 22, 2020).

The writer, Mr Peter Heng, said researchers have discovered that rooftop solar installations raise local temperatures by creating a solar heat island effect similar to that of industrial areas.

This is because solar panels are usually made of dark materials that promote high solar irradiance. Such materials absorb a relatively high amount of solar energy over a given area and emit most of it back into the environment.

The studies revealed that solar farms have the potential to raise ambient air temperatures by 3 deg C to 4 deg C.

Mr Heng also said that because of Singapore's tropical climate, the energy costs of counteracting this heat island effect, through air-conditioning, for example, may more than offset the energy generated by solar installations.

He added: "In fact, a 'greener' and cheaper solution to reducing our overall contribution to global warming (and not just our carbon footprint) may be to simply paint our roofs white."

Therefore, installing rooftop solar panels may not result in much energy savings, as air-conditioner use will increase because the roof will be very hot.

The resultant overall increase in ambient heat in the living environment will also discourage outdoor activities.

Leslie Lim