Equally as important as a properly sized solar collector array is a properly sized storage tank. The storage tank acts as a thermal battery and provides energy to the water heating loads in the building to reduce the use of conventional electric or gas heating methods. Storage tanks must be sized based on the water heating load and solar collector array energy output value. Temperatures in the solar storage tank usually range from groundwater temperature in the morning to 140-170° F in the afternoon.
As a simple rule of thumb the storage tank should be sized based on 1.5 gallons of storage per square foot of solar thermal collector used. For example, if the system calls for (16) SLSG-40 collectors then the total collector area is 640 ft2. This would require 960 gallons of storage volume. Keep in mind that this is a rule of thumb to obtain a “ball park” figure. This figure should be compared to estimated hot water usage figures, specific climate data, and other data to obtain an accurate value. Contact Solene’s Engineering Department for specific system design and analysis.