This 4-bedroom detached house has achieved ‘Passivhaus’ standards of insulation and airtightness.   Invicta Clean Energy installed a solar ‘combi’ system with 2 x 30 tube solar collectors linked to a vented thermal store to provide hot water and space heating.


The solar collectors are steeply pitched at 55° to maximise winter solar gain and to minimise the potential for summertime overheating. A bypass radiator located in a sunspace is used to dissipate excess heat during periods of low consumption or peak irradiation. Careful attention was paid to the detailing of the roof penetrations which are required to be air tight.


The thermal store includes twin solar coils to promote stratification and priority charging of the upper body of the cylinder. Mains pressure hot water is supplied via an external plate heat exchanger activated by a flow switch. Heat from the store is supplied to a mechanical ventilation with heat recovery (MVHR) system to supplement the recovered heat. Heat transfer is via a water to air heat exchanger located within an inline duct heater.