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Going Solar

HKGCC visited Hong Kong's largest solar electricity generation system to see if the technology is mature, and cheap enough to go mainstream

Solar electricity generation facilities at Wanchai Tower reduce the building's contribution to greenhouse gas emissions by 23 tonnes annually. The project, the largest solar electricity generation system in Hong Kong, is a pilot scheme run by the government's Electrical and Mechanical Services Department (EMSD) to determine if photovoltaic (PV) solar panels installed on buildings can be practical and economically viable.

To find out more about the project, the Chamber organised a site visit to the tower on November 18. Dr Kwok Yu-fat, building services engineer for the EMSD, said the entire system, consisting of 500 sq. meters of PV panels installed on the building's roof and windows as shades, cost HK$8.15 million. The total peak capacity of the system is 55 kW.

Electricity generated by the panels is fed into Hong Kong's power grid, which was made possible after discussing the project with Hongkong Electric, he said.

Impressive as the system is, it still only accounts for just 1 percent of Wanchai Tower's total energy consumption. However, Dr Kwok said he hasn't done any studies to determine if the solar panels mounted on windows, which shade rooms and thus keep them cooler, has helped to bring down the building's air conditioning usage.

All PV panels have been installed facing south to receive maximum solar irradiation. To demonstrate the applicability of photovoltaic technologies locally, the BIPV system is divided into three different sub-systems:

1. A rack sub-system comprising poly-crystalline PV panels on the upper roof of the building;

2. A sunshade-screen sub-system comprising mono-crystalline PV panels in the form of double-glazed panels complete with integrated PV cells. The panels are externally mounted on the building facade to provide shading for the upper portion of all south-facing windows from 1st to 12th floors; and

3. A skylight sub-system comprising mono-crystalline PV panels in the form of double-glazed panels complete with integrated PV cells. It is mounted vertically to replace some of the glass-infill of the existing glass atrium at the front entrance hall.

Although installation costs for panels are high, Dr Kwok said costs could be substantially reduced if architects designed buildings to incorporate solar panels at the conception stage. They then would also be able to maximise their effectiveness by positioning panels at their ultimate power generation angle.

"The panels are quite expensive, but their cost is coming down all the time. As the life span of the panels is about 20 years, it could be commercially viable over the long term," he said.


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