Solar PV cells have an efficiency of about 15%. What is the collectible power density in Hong Kong?

Solar Thermal: The average power of sunshine per square meter in Hong Kong is nearly impossible to find, due to this region's area oriented towards the sun and the tilt between the sun and land being hard to find. Therefore, it is to be assumed that the average power of sunshine per square meter on roofs in Hong Kong is 110 W/m². The average power of sunshine per square meter on the ground is also assumed to be 110 W/m². Also, McKay informs us that if all south-facing roofs had solar thermal panels, this would be 10 meters squared. This seems very generous, so I will go 7 meters squared of roof panels per person. These panels are approximately 50 percent efficient. Thus, the potential of solar heating is (110 W/m²)(7m²)(.50). The end result for solar thermal is approximately 9 kWh/day/person.

Solar Photovoltaic: I will give each person in Hong Kong 7 meters squared of photovoltaic panels and 110 W/m² is used again as the average power of sunshine per square meter. According to McKay, only the expensive PV panels have an efficiency of 20 percent. Most PV panels fall in between 10-20 percent. I will go in the middle and say that the PV panels are 15 percent efficient. Using this data, the total power per capita per day for solar PV is approximately 3 kWh/day/person.

Solar farming: Once again, I will use 110 W/m² as the average power of sunshine per square meter. Like McKay, I will assume that a breakthrough occurs in the solar energy industry, both technological and economical, and will cover 5 percent of the land with PV panels that are 10 percent efficient. 10 percent is the on the low-end for efficiency, but the PV panels are assumed to be cheap, meaning this is reasonable. Also, I know that Hong Kong covers 157.5 meters squared per person. Plugging in numbers, I get 2 .0 kWh/person/day.