Q: What is the best way to reduce my fuel bills by incorporating a solar thermal system?
A:Reduction +Reduction = Reduction
This should come at no surprise to any of our readers but the single best way to save money on energy bills is by reducing your consumption. It is surprising to me still, to find that at least 90% of homeowners that purchase a solar thermal system to reduce their energy bills have made no other provisions for energy reduction. By simply changing shower heads and turning set point temperature by 5 degrees, a homeowner can reduce their DHW load by nearly 25%. When coupled with a solar thermal system they can approach, easily, a 75% reduction. If we look at a broader approach with a more holistic solution, the impact becomes greater, the payback goes down and the return on investment increases markedly. Take a look at heating systems for example as well. Many in the US require fairly high temperature setpoints in order to deliver high quality btus to the home. If we tie a solar thermal system into a home heating system that require such high temperature as 160-180 Deg F then we are sacrificing a considerable difference in collector efficiency. By reducing the temperature setpoint of the home heating system, installers can essentially get more BTU’s out of a Solar thermal system. The most important factor that determines collector efficiency (that you have any control over) is the incoming temp to the collectors, therefore the lower the incoming temperature is, the higher the output will be. In other words, you get more by requiring less. For example, a heating system in the North East Us that uses baseboard emitters requiring 170 deg F will see an average efficiency during the winter months of nearly 35% for Evacuated tube collectors, and much lower still with Flat Plates, IF the installer couples the system with setpoint reduction measures (i.e. outdoor ambient reset, lower temp heat emitters, radiant floor tubing replacing baseboard etc) then the total collectors efficiency can nearly double. This means MORE useable BTU’s!!
REDUCTION in Load and REDUCTION in temperature means REDUCTION in payback!!
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