China has abundant solar-energy resources. Beyond large-scale developments in the photovoltaic industry, consider an individual solar panel: how many kilowatt-hours can it generate in a year? Many people would find that question difficult to answer.

This involves two determinants of photovoltaic power:

First, the power of photovoltaic panels.

Second, the area available for photovoltaic panel installation.

For the same panel area, higher photovoltaic output means less time is needed to generate one kilowatt-hour and more electricity can be produced in a day.

Photovoltaic panels generate electricity from sunlight, so they do not generate power at night. Windy, foggy, rainy and snowy weather can also greatly limit generation. Output therefore depends closely on the installation location: identical panels can produce different amounts of electricity in different regions. Locations with abundant sunlight have an advantage.

On average, a photovoltaic panel produces about 400 kilowatt-hours of electricity a year.

Why is this a theoretical estimate? In addition to panel power and the installation location’s equivalent annual operating hours, photovoltaic output depends on installation angle and orientation, local climate, cable materials, and shading.

Photovoltaic panels need the correct installation angle and orientation to receive enough light and perform effectively. Installing them arbitrarily, such as laying them flat when a tilt is required or facing them north instead of south, can reduce power generation.

Days of rain, snow, long-term haze, dust storms, and so on, even the sun can not see, no matter how good photovoltaic panels can not generate electricity.

Poor-quality cables and wiring waste electricity and can create accident risks. Increasing generation does little good if energy is lost in the wiring, so material quality is important.

Keep photovoltaic panels clean and free of shade. Nearby trees or tall buildings can limit direct sunlight to just a few hours, reducing generation. Site selection therefore matters. In windy or sandy areas, dust accumulation also reduces output if panels are not properly maintained.

These factors all affect photovoltaic power generation. Regular, careful maintenance helps the system generate more electricity.