Which of the following can be a major factor for reduced performance in a PV array during summer?

Increased ambient temperature is indeed a major factor that can lead to reduced performance in a photovoltaic (PV) array during summer. Solar panels are designed to convert sunlight into electricity, but they also have an optimal operating temperature range. As the ambient temperature rises, the efficiency of the solar cells typically decreases. This is because higher temperatures can lead to an increase in the electrical resistance of the materials in the solar cells, resulting in lower voltage and subsequently reduced power output.

While increased cloud cover can reduce sunlight reaching the panels and thus impact performance, this is generally more pertinent in cooler months or during specific weather events rather than consistently in summer. Excessive wind may have minimal effects on performance but is unlikely to be a significant factor during hot summer months; rather, it might cool the panels slightly. Soil quality is not directly relevant to the performance of the PV array itself, as it pertains more to ground-mounted installations and their stability rather than the operation of the solar cells.

Thus, the correct reasoning highlights how temperature directly affects the operational efficiency of solar panels, making increased ambient temperature the primary factor for reduced performance during the heat of summer.