NEW! NOW TWO SYSTEMS ARE ON LINE FOR YOU TO FOLLOW LIVE DATA MONITORING. CLICK HERE!
My favorite new hobby is using my smartphone to check the live data logs for my home’s solar thermal system.
I’ve preached before that live data logging provides the best tool to analyze performance and system design. Looking at historical data improves your understanding of how the system is performing and if it’s reacting to any condition that may conspire to reduce its efficiency. For example, performance data can tell you if a sensor is not located correctly or sensing adequately; or it could help determine how to adjust pump speed control.
Rod’s data logging system
Here’s an example from my own system: I found in the summertime that the pump would sometimes turn on in the middle of the night. After analyzing the data, I realized the problem was a controller setting that had the pump come on when the bottom tank temperature came within 12 degrees of the temperature of the solar collectors. So, if the collectors were at 80 degrees, and cold water was introduced into the solar storage tank, the pump would come on and try to find heat that wasn’t there, resulting in short-cycling. The solution was to reset the controller with a higher minimum collector temp – that is, higher than what ambient temperatures would be at night.
My system’s data logging can be viewed at: http://askrod.dyndns.info:9831/CRD/index.html
What you’ll see represents one vacuum-tube panel heating a 119-gallon tank. The data logs easily show the stratification temperatures in the tank from three sensors placed in the bottom, middle and top. You can also see pump speed, as well as the Btu’s being delivered from the solar panels.
I’ll be continually fussing with and upgrading my own data logging system, and I’ll keep you informed of any changes. Just a note: For some reason, this link cannot be viewed with Explorer. Try another browser such as Firefox or Google Chrome.