Which of the following is a factor that affects solar energy efficiency?

The efficiency of solar energy is influenced significantly by the type of solar panel material and the weather and environmental conditions. Different materials, such as monocrystalline or polycrystalline silicon, have varying abilities to convert sunlight into electricity, which directly impacts efficiency. For example, monocrystalline panels are known for having higher efficiency rates compared to other materials due to their higher purity and ability to capture more sunlight.

Weather conditions, including factors like cloud cover, temperature, and the angle of sunlight, also play a crucial role. On cloudy days, solar panels receive less direct sunlight, leading to decreased energy production. Additionally, extreme temperatures can affect the performance of solar panels, as higher temperatures can reduce efficiency.

Overall, both the type of solar panel material and the environmental conditions must be considered together when evaluating solar energy efficiency, making the combination of these factors the correct choice. The number of electric devices in use, while important in terms of energy consumption, does not directly influence the efficiency of how solar energy is converted to electricity.