To safely and optimally determine the size of solar thermal collector array the calculated water heating load should be matched to the expected output of the solar array. For initial sizing purposes we can use the rating published by SRCC for Category C, High-Radiation conditions. The Solene AR Series is rated at 1095 BTU/ft2-day and the Solene SG Series is rated at 1070 BTU/ft2-day. In reality the power output of the solar thermal collectors varies constantly with solar insolation and weather but using the figures as noted helps ensure that the system is sized so that it will not stagnate during the warmest, brightest months and possibly cause issues due to extreme temperatures and pressures. A multiplier of 1.20 should factored into the sizing result to make up for real-world energy losses from piping, tanks, etc. Using the previous example of the apartment building, and assuming the Solene SG Series collector will be used, the system would be sized as follows: 1.20*[(475,809.6 BTU/day) / (1070 BTU/ft2-day)] = 533.6 ft2. The calculation yields a result of 533.6 ft2 which would equate to (14) SLSG-40 collectors. It should be noted that the collectors will not perform at this level 100% of the time but, conservatively, should yield a solar fractions of 50-75% over the course of a year.