|Compare the PV and the Sunboxes|
What's there not to like about that? (Listen up Navitrolls!)
This graph is comparing the PV and the Sunboxes at weekly intervals, since Mid March'10 when the Sunboxes were turned on. Throughout Summer 2010, it's clear that the PV whacked the Sunboxes consistently. Since the Autumn Equinox, there was a big change. The aluminium mirrors were fitted to the Sunboxes, but also, the heating came back on. We had an unusually Cold Autumn-Winter, and during this period, the GSHP gets very active, thus boosting the activity of the Sunboxes by using them as a real-time heat source.
Therefore I am still not clear whether the gigantic improvement in the Sunbox performance was due to the heating demand (and the equivalent reduction in earning of the PV), or due to the additional boost from the mirrors. The only we we will know for certain will be to reproduce this graph at the end of 2011, to compare the two summers and winters. Chris Wood is certain it is the heating effort, and agree 50%, but I also have a belief in my mirrors being the other 50%!
This graph runs for 13 months, and we can already see the difference between last March-April'10 and this one. During this time, the GSHP has been almost totally dormant, so the Sunboxes are working on summer mode - storing heat, but not using it in realtime - and they are doing better than for much of last Summer.
This heatwave also demonstrates one reason why the performance figures of the house and GSHP are breaking records every week - last Spring 2010 was unusually long-lasting in the cold wintry weather. The first day with an evening temperature above 10º was March 17th ! But at the same time in 2011, the GSHP is not heating at all, it is on Hot water duty only!