The amount of electricity a solar array produces varies with sunlight availability and environmental conditions. Understanding what drives that variation helps you read real-world output sensibly.
The sun's path through the year
Because the Earth is tilted on its axis, the sun's path across the sky changes with the seasons. In summer the sun climbs higher and stays up longer; in winter it rides lower and sets earlier. The same applies at different latitudes year-round: nearer the equator, the sun passes high overhead; nearer the poles, it stays lower. Panels receive the most energy when the sun's rays strike them as directly as possible.
Orientation and tilt
In the northern hemisphere, surfaces facing south capture the most direct sunlight across the day; in the southern hemisphere, the reverse applies. Tilting panels toward the sun's average height — often near the site's latitude — helps them intercept more light. A panel lying flat still works; it just receives fewer direct rays at most latitudes.
Shading matters more than it looks
Shade from trees, chimneys, or neighboring buildings can reduce output sharply, because a shadowed cell can hold back the string of cells it is wired into. Small shadows can mean disproportionately less power, so assessments focus on keeping the array clear of shade during the sunniest hours.
Weather and temperature
Clouds reduce output, though panels still generate on overcast days. Temperature matters too: panels actually perform a little better when cool, and very hot conditions reduce their output somewhat. A clear, cool spring day can be a better day for generation than a scorching summer afternoon.