We will often use technologies in combination. For example, a heat pump will operate most efficiently at a low flow temperatures, ideally between 35 and 40°C. Its efficiency will drop, i.e. it will use more electricity, when it generates hot water at a higher temperature, typically 55°C. Combining a solar thermal collector with a heat pump will improve the overall efficiency (seasonal performance factor) for the heat pump by minimising the extent to which it is required to generate hot water at elevated temperatures.
PV systems will typically benefit from having a solar switch installed. This device works by sensing when you are generating more electricity that you are using onsite and then it diverts electricity to a demand in the house such as switching on the immersion element in your hot water cylinder. This can provide a substantial amount of your domestic hot water in the non-heating season.