The government's new SAP calculation was used to calculate the energy from a solar panel for an average sized house of 80m2 floor area. The panel was assumed to face south, at a tilt angle of 30 degrees, with little or no overshading. The hot water store was fixed at 180litres, compared to the daily demand of 102 litres.

The area of solar panel was varied and the plot shows the annual solar energy contribution.

Two types of solar panel were modelled, a high efficiency tube (zero loss efficiency set to 0.8, heat loss coefficient set to 2.0) and a flat plate solar panel (zero loss efficiency set to 0.8, heat loss coefficient set to 4.0)