Forum: Lighter-coloured solar panels could ease heat effect

I refer to Mr Peter Heng Teck Wee's letter (Floating solar farms may do more harm to environment than good, April 28).

The drawbacks he highlighted refer mainly to the traditional black or dark blue solar panels.

Black solar panels produce more electricity, but may also emit more heat.

Cooling Singapore, a research project aimed at tackling the urban heat challenge here, recommends that roof surfaces, building surfaces and even roads and footpaths be painted white or in light colours, to reduce heat build-up.

Therefore, putting dark-coloured solar panels on any surface, whether building surface, land surface or even water surface, seems to contradict this recommendation.

Solar panels are made from solar cells, which are not the problem. The problem is the black colour, which is the best absorber of light, thus enabling the cells to produce the most solar energy.

Unfortunately, black is also the best absorber of heat.

Up to 85 per cent of heat absorbed will eventually be dissipated to the environment, causing the urban heat island effect.

So if black is the problem, then would a light-coloured solar panel, such as one that is light grey, solve the problem?

Light-coloured solar panels would at least mitigate the amount of heat transmitted to the environment.

But in the course of my work on solar panels, I realised that any colour of solar glass placed over the black solar cell would reduce the energy performance of the solar panels substantially.

Today, there is game-changing technology that can produce nearly the same amount of solar energy as black solar modules.

It is a special glass-coating technology which transmits the selected coloured wavelength while allowing more than 90 per cent of the visible light to transmit through the glass to excite the black solar cell.

I believe that these coloured solar panels, with colours which are much lighter than the traditional black or dark blue solar cell, should naturally be able to mitigate the heat island effect without substantially compromising energy efficiency.

Philip Kwang