Quick Answer
A solar still requires at least 4-6 hours of direct sunlight to effectively evaporate and condense water, with the ideal being 8 hours of full sun. This can be achieved when the still is positioned with an unobstructed view of the sun, ideally south-facing. The surface temperature should not exceed 120°F (49°C) to prevent water loss.
Positioning for Optimal Sunlight
Positioning the solar still for optimal sunlight is crucial for its effectiveness. A south-facing orientation receives the most direct sunlight during the day. If the solar still is in a location where the sun’s position changes throughout the year, such as in the northern hemisphere, position it slightly east of south to account for the sun’s seasonal movement.
Understanding the Role of Insolation
Insolation is the amount of solar radiation that reaches the Earth’s surface, measured in kilowatt-hours per square meter per day (kWh/m²/day). For a solar still to work effectively, it requires at least 4-6 kWh/m²/day. This translates to 4-6 hours of direct sunlight per day, depending on the intensity of the sun. Use a solar still positioning guide or consult with a local expert to determine the optimal angle and direction for your location.
Measuring and Maximizing Surface Temperature
The surface temperature of the solar still should not exceed 120°F (49°C) to prevent water loss. You can measure the surface temperature by using a thermometer or a pyrometer. To maximize the surface temperature, use a dark-colored surface material and position the still in direct sunlight. If possible, use a reflective material, such as aluminum foil, to increase the surface temperature by reflecting additional solar radiation onto the still.
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