20 August 2012: I am having to write up a bit about the thermal performance of the Tubes versus the Sunbox, so here is a quick summary of the meter readings. We have had a lousy summer, and I would expect all figures to be low for this year. The Tubes have underperformed, but the combination of the Tubes with the Sunbox have still achieved a higher thermal figure for Summer 2011 or 2010. These are meter readings for exactly three months of the summer of the last three years. In keeping with the higher overall figure, the measured deep ground temperature in Summer seems to have topped out at a higher figure (13.7ºC) than in previous years.
In 2012, the old energy meter was shifted to the tubes, and the sunbox got a new meter which started from zero. For comparison purposes, the fairest time to start from is 12 May 2012 when the heat exchanger was finally fitted and working. Three months of the summer is a good quarter over which to test the technologies.
I future years, I hope to have an additional set of columns, those showing the performance of the PV-Thermal that I intend to fit on the extension.