How do I know if my system is performing the way it should be?

First of all, your system performance will be measured by BTU’S produced, NOT by temperature achieved. The simplest way to accomplish this is by following this method:
1- Record your solar tank temperature first thing in the morning, before the solar pump turns on.
2- be sure that no one uses hot water during this day.
3-Record your solar tank temperature at the end of the “solar” day
4-Perform this calculation to determine total btu’s produced
Change in tank temp Deg F x Total gallons in tank x 8.3 = total btu prod/day
5-View the SRCC certificate for estimated performance or call you SunMaxx sales rep to get an expected performance number