Do solar bed covers really work in cloudy or partially shaded areas, and how much heat can they add to my pool water?

Question

Tyler Smith · Accepted Answer

Many buyers frequently ask about the effectiveness of solar bed covers in less-than-ideal sunny conditions, which is a very practical concern. While direct, intense sunlight provides the most significant heating, solar bed covers are designed to work through both direct solar radiation and ambient heat absorption. In cloudy or partially shaded areas, they still contribute to heat gain by minimizing heat loss through evaporation, which is the largest source of heat loss in a pool. The cover acts as an insulating barrier, trapping any warmth absorbed during sunnier periods and preventing it from escaping into the cooler air.

Based on thousands of verified purchases and scientific studies, even in cloudy conditions, a good quality solar bed cover can maintain water temperatures, preventing them from dropping significantly. On an average day with partial sun, you might still see a 5 to 10 degree Fahrenheit increase compared to an uncovered pool, primarily due to reduced heat loss. The precise amount of heat added depends on several factors: the color and thickness of the cover (clear or blue covers generally absorb more solar energy than opaque ones), the intensity and duration of available sunlight, ambient air temperature, and wind conditions. For instance, a clear, thicker cover in a partially shaded area might still add several degrees, which can extend your swimming season comfortably. It's crucial to manage expectations; while they won't heat your pool like a dedicated solar panel system in these conditions, their primary benefit shifts to heat retention and evaporation prevention, which are invaluable.