|Yellow is the kilowatt hour PV capture|
Blue is the kilowatt hour capture of the Sunbox
Red is the Degree Days, indicating heating demand in Nottingham
The red line indicates the Degree Days as an index to the heating requirements. It is based on the weather records from the East Midlands Airport, nearby.
There is a brief moment in April and October when there is a gentle peaking of the Sunbox capture. The GSHP is working because the heating season has started, but there are still a number of warm sunny days (we wish!). When the GSHP is working there is a delta-T in the system which helps to capture more heat (at a lower temperature).