Improve Performance of Solar Collectors
I am trying to improve the performance of the solar collectors in my simple simulation where two collectors (one on the south facing roof, one on the south wall) supply a hot water heating coil for a small space. Regardless of how I set up the schedule for the fan availability for the air loop or the coil availability, the 'solar collector heat transfer energy' shows that while the fluid gains heat throughout the year, it also loses heat. Surprisingly the heat loss is greatest in the summer time. I have also noticed that the efficiency of the panels throughout the year varies from 0 to large negative numbers.
I know that solar collectors perform better than this in the real world. I looked through the solar collector data set and made a simulation comparing all of the evacuated tubes, from which I chose the Thermomax Industries Ltd collectors as they seemed to perform the best. However, using the efficiency equation coefficients and incidence angle modifier coefficients given in the data set for the Thermomax panel, the outlet temperature never got higher than 50 at any time of the year.
I am very confused as to why the panels in my simulation perform so differently from the real world. Has anyone else had this problem? If so how did you fix it? I used OpenStudio 1.10.0 for this simulation.
Thank you.