Hybrids refer to an appliance or a system of appliances which combine at least 2 different energy sources and whose operation is managed by one control. Among the hybrid systems, many combinations are possible. For example, a gas or oil condensing boilers can be combined with a solar thermal installation plus a hot water storage tank. Or an electrical / gas heat pump (inclusive drinking water heat pumps). Or a biomass boiler. Or a ventilation with or without heat recovery. Among the hybrid appliances, the most common product is a hybrid heat pump, which combines an electric heat pump with a gas condensing boiler. The hybrid heat pump’s master control manages the operation of the boiler and heat pump.
Mix and match for optimal results
Why did the heating industry invest in the development of these hybrids and the possibility to combine different energy sources?
Each technology and each energy source has its own advantages as well as downsides. This has led manufacturers to consider the feasible combinations of existing technologies and energy sources, in order to maximise their benefits and compensate their weaknesses. Hybrid systems can offer tailor-made solutions to respond to diverse heating needs (regardless of the building’s size, use or location), the availability of – renewable – energy sources such as biomass.
Introducing renewable heat and hot water anywhere
Hybrids can be installed in almost any building, regardless of its energy demand. For a lot of existing buildings, a simple switch from a gas or oil boiler to renewable heat is not possible. Relying exclusively on a heat pump or solar thermal collectors – delivering low-temperature heat – is often not possible, as most existing buildings are not equipped with an adequate low-temperature heat transfer system. Especially when the outside temperature drops, the hybrid’s ability to switch to a high-efficiency boiler can maintain higher flow temperatures for the central heating system to keep the house warm.
Some examples to illustrate this: Solar thermal collectors will provide the bulk of a family’s hot water needs, but the boiler takes over when the outside temperature is really low or demand is very high, think guests visiting and taking showers. A hybrid heat pump will deliver the bulk of a building’s heating, unless the heat pump is not able to work efficiently. During the few really cold days of the year, the boiler will cover this peak heat demand.
Convincing consumers to give up on their familiar and reliable boiler – even when it is old – and switch to lesser known renewable heat technologies is often a major challenge. A hybrid can help to overcome this hurdle, as it offers the reassurance of e.g. the condensing boiler as a back-up.
Helping the grid manage more renewable electricity sources
An increased market share for hybrids offers an opportunity for the heating sector to do its part to help balance a grid with a growing share of variable sources of solar and wind power. Such balancing can happen as ‘load shedding’ when switching from the heat pump to the fuel boiler, at times when electricity demand is high and the grid is stressed. Or balancing can happen as ‘peak absorption’ by switching from the boiler to the heat pump, when renewable electricity is abundant and power prices are down. Another possibility is using cheap renewable electricity to produce hot water as a form of energy storage.