What sets this solar thermal installation apart from many others is the variable speed pump control and the reverse return collector. In periods of lower solar radiation (late/early day, winter and overcast/cloudy) and when there is a higher storage tank temperature, traditional fixed flowrate circulating pumps will shut the pump off to avoid cooling the storage tank. Even though there is energy available. By slowing the loop flowrate down, more energy per unit volume of loop fluid is collected, driving the return temperature back up above the storage temperature. Simple and effective.
Variable Speed Solar Pump
By varying the speed of the pump, up to 20% more annual energy can be collected, with the rest of the system unchanged.
Evacuated Tube Solar Thermal Collector
This collector has excellent performance in low solar conditions such as when it is overcast and raining. The evacuated tube permits very little convected and conducted heat transfer which makes it tolerant to low ambient outdoor temperatures and windy conditions. Unlike heat pipe type evacuated tube collectors, each tube in this collector has a copper loop in the absorber plate, with them all manifolded, reverse return, in the header. This means superior performance at a significantly lower cost.
All of these benefits add up to a system that performs very well, year round, in our coastal climate.
With this system we can expect to displace nearly10 GJ/year of natural gas, and with an expected life of 20+years, that’s a lot of carbon!