The first consideration in system design is the size of the hot water load. Consult the BS Standards, ASHRAE or some other recommended procedure to determine the number of Litres of hot water needed per day after which you can proceed and size your Solar system components. The size of the load determines the required storage capacity and the size of the collector field...This is a guide in brief...
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| Solar collector and Tank. |
(a) Size the system to provide 65 percent of one day's hot water load. The collector array size needed to heat the tank is approximately 0.01 to 0.02 square metres per litres of storage.
(b) Use a solar system simulation computer program to refine the component sizing.
(c) Be careful to match the size of the collector field and the solar storage tank capacity. A mismatch causes the storage tank to be either too hot or too cool for optimal performance.
(d) Be sure to specifyseparate tanks for solar storage and backup heating. These two functions must be kept separate especially in a commercial system.
(f) If possible, specify a vertical, not horizontal, storage tank. The vertical tank provides better temperature stratification than the horizontal tank, enhancing overall system performance.
(g) Situate the system components as close as possible to the usage points. We saw systems located so far (up to 500 feet) from the load that much of the heat was lost in the interim piping. Whether or not the collectors are placed on the roof or the ground is a decision that is usually based on aesthetics and fear of vandalism, but it should also be based on system line lengths. Reducing system line lengths is desirable
In our next articles we will write about Types Of Solar Water Systems. Read, Learn and Share.
