Hong Kong consumes an enormous amount of electricity, with the majority generated from coal and nuclear sources, and less than 1% contributed by renewable means. Given that 97% of the city’s carbon dioxide emissions are the result of electricity generation, there is an urgent need to develop other sources of pollution-free renewable energy. Dr Charles Wong at the Department of Land Surveying and Geo-Informatics and Dr Vivien Lu at the Department of Building Services Engineering discussed the findings of their study on the viability of solar photovoltaic energy generation in Hong Kong.

What are the benefits of solar photovoltaic energy generation?

Solar photovoltaic energy is a clean source that can be integrated into the walls, roofs and windows of buildings without taking up additional land space. Solar photovoltaic panels can even replace traditional building façade structures and help reduce the use of other building materials.

Please briefly explain your study.

To investigate the installation capacity, energy generation capacity and environmental benefits of investing in solar photovoltaic energy in Hong Kong, a solar radiation transmission model has been developed to calculate the annual solar radiation amount in Hong Kong. We have also used high-resolution airborne laser scanning data and geographical information systems data to map the available rooftop area in Hong Kong in order to estimate the potential of installing solar photovoltaic systems on rooftops.

Where were the findings?

The data collected from the solar radiation transmission model indicated that Hong Kong enjoys sunshine for more than half of its days in a year. The city is therefore highly suitable for solar power generation. We have also found that out of the 309,000 buildings in Hong Kong, 233,000 are suitable for installing solar photovoltaic panels, with a total area amounting to 39km2. The potential annual solar energy output can reach 4,674 Gwh, or 10.7% of Hong Kong’s energy consumption, reducing greenhouse gas emissions by three million tonnes.

What is the drawback to solar photovoltaic energy generation in Hong Kong?

The costs of purchasing and installing solar photovoltaic systems in all local suitable rooftop areas are very high, amounting to HK$30 billion, which is three to four times higher than in mainland China.

Do you have any expectations in reducing the costs?

Although the purchase and installation costs seem high, it will only take around two to three years to pay back. With an average lifetime of 25 years, the solar panels will provide 25 years of clean electricity.

In addition, the market of solar photovoltaic applications in Hong Kong is still small and costs will come down as market capacity increased. It would be ideal for the government to provide subsidies to ensure that the price of solar photovoltaic energy is competitive to that of the electricity generated by traditional technologies.