Despite the constraints on developing large-scale renewable energy projects in Hong Kong, CLP strives to explore different opportunities in the local community. Solar energy is one of the cleanest sources of energy with abundant supply. Do you know how to measure solar energy performance? Or what do you need to consider when installing solar device at home? CLP has the answers for you.

Solar Energy Potential

Solar energy potential in a given location is mainly determined by blockage which refers to buildings or objects located directly in the sun’s path. Even temporary blockage of sunlight limits the number of hours and days of solar energy in a year.

Solar energy potential is the highest in the summer and on average this figure is relatively steady over the course of a year in Hong Kong.

Solar Energy Index

Solar Energy Index is the measurement of potential solar energy within a specific area. The lower the blockage level, the higher the solar energy index, and the higher the solar energy potential.

Solar Energy Index

Blockage Level

High (>90%)

Low

Medium (60% - 90%)

Medium

Low (<60%)

High

How to Measure Solar Energy Index?


1. Decide on the location where you want to install your solar panels. Face south and take a 360° panorama picture. Then overlay the sun path on the picture.

2. Determine whether the blockage obstructs the sun path (the fewer blockage is beneficial for solar photovoltaic panels to absorb solar energy).

3. According to the sun blockage on different time of the day and different season of the year, you can calculate the Solar Energy Index.

Solar Photovoltaic (PV) Comparision

PV Type: Mono-crystalline (Crystalline)

Manufacturing method:

Made from a single continuous crystal lattice structure

Cell efficiency: 20% - 25%

Equipment Cost: HK$ 24 - 40/ watt

Advantages:

• Highest efficiency

Disadvantages:

• Complicated and relatively expensive to manufacture;

• Heavy weight compared to thin-film installation

PV Type: Poly-crystalline (Crystalline)

Manufacturing method:

Silicon wafers are produced by casting and saving or by forming thin ribbons directly from the silicon melt

Cell efficiency: 10% - 24%

Equipment cost: HK$ 24- 40/ watt

Advantages:

• Cheaper than mono-crystalline cells;

• Simpler and less energy intensive to manufacture than mono-crystalline cells

Disadvantages:

• Less efficient than mono-crystalline cells;

• Heavy weight compared to thin-film installation

PV Type: Amorphous silicon (Thin-film)

Manufacturing method:

Use a homogeneous layer of silicon rather than a crystal sturcture

Cell efficiency: 6% - 9%

Equipment cost: HK$ 16 - 24/ watt

Advantages:

• Cheaper than crystalline cells;

• Can use on curved and flexible surface;

• Light weight

Disadvantages:

• Less efficient than crystalline technologies

Requirements of Installing Solar Energy Devices

You may consider installing solar energy equipment on your roof and/or permanent open areas. For solar  photovoltaic (PV) installation, it requires extra space for the inverters and related equipment while minimizing the shaded areas.

For the best results, position your solar energy equipment at an elevated angle of 22.5º facing south.

For further information about technical problems, please visit Technical Guidelines

CLP has launched a number of new initiatives to encourage the community to embrace low-carbon lifestyles by promoting the development of renewable energy and energy conservation. Sign up for our renewable energy schemes today and build a sustainable future together.

For more details, please visit the Renewable Energy Feed-in Tariff Webpage .

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