SunMaxx Solar Heating System Performance

As noted in a previous post, the solar heating system has undergone some revisions. As a result of the upgrades a morning of performance measurements were collected from the SunMaxx solar heating system used to heat the pool.  Sunrise was at 7:10 AM (January 31, 2012) but the sun did not crest the mountains until about 8:00AM.  Even then the sky was overcast with high cirrus and small cumulus clouds and it was not until about 8:45 that enough sunlight penetrated the cloud cover to start the heating cycle in the solar panels.  The amount of overcast is shown below in a photograph recorded at 11:30 AM (time of reading) to visually demonstrate the amount of cloud cover. The collector temperature, pump speed (in percent of the maximum 1.5 gpm), and the temperature in and out of the heat exchanger were recorded at one minute intervals throughout the morning.  The sun would creep behind the clouds then reappear causing the pump to cycle up and down in response the the temperature fluctuations measured at the solar panels. The cycling of the pump appears to minimize coolant temperature fluctuations reaching the heat exchanger resulting from fluctuations in sunlight by slowing the flow rate when less sunlight is available for heating, note the "oc" and "s" on the graph and compare with heat exchanger temperatures.  A maximum of 127 degree coolant was produced by the panels during the measurement period, while 114 degree coolant was reaching the heat exchanger, with a maximum of 20 degrees differential across the heat exchanger.  The solar panels work well and combined with well insulated stainless steel lines which minimize heat loss across the run between the solar panels and pool house high temperatures at the heat exchanger are reached .  It is also pleasing to note that even on an overcast January morning the panels easily produce heat which can be used in the pool.

Solar collector performance

Cloud cover at 11:30 AM, panels producing 120 degree coolant and 109 degrees
at the heat exchanger.

Solar panels used to heat the pool at the Painted Pony Resort

The Solar System at the Painted Pony Resort

As noted in a previous post the solar system heating the pool required some reworking.  A new pump station was installed which contains all the essentials for filling, monitoring, and running the solar system.  This unit, built by SunMaxx Solar, contains fill and drain ports, an inline pump, a one way valve, an electronic controller, a flow meter, a pressure gauge, an air purge, a pressure relief valve, and analogue thermometers.  It replaces a  series of parts installed inline which did many of the same functions except the pressure gauge and flow meter are new.  Previously, to check flow and pressure required a trip to the collectors to draw off some coolant which had to be replaced simultaneously to maintain flow throughout the system.  Now a simple visual inspection reveals the flow rate and the same for the pressure.  The original pump was left inline as a backup but all the old copper plumbing and brass fittings were removed.  The unit comes completely insulated minimizing heat loss which insures the maximum amount of heated fluid reaches the heat exchanger (the connecting pipes were also insulated).  The system is still connected to the shortened PEX lines but these will be replaced with stainless steel flexible insulated piping, eliminating any possibility of overheating and blowouts.

The pool was at 71 last night and the maximum temp observed at the solar collectors since installing the pump station was between 115-120 F. 

SunMaxx pump station