Heat Pump Vs Solar Hot Water
How They Work:
Heat Pump Hot Water Units:
Heat pump hot water units use the heat in the air and require no direct sunlight. The air around the heat pump unit is drawn into the system via a fan and into an evaporator. An Evaporator contains a particular type of refrigerant, provided in piping called R134a.
R134a's evaporation or boiling point is -26C, compared to water that has a boiling point of 100C. Temperatures that are cold to us make the refrigerant boil. The air drawn into the heat pump unit, which is far warmer than the refrigerant, turns the refrigerant liquid to a gas inside the heat pump's piping.
The heat pumps compressor then pumps the refrigerant, that is now a gas, through a small valve to compress it, this generates a great deal of heat.
The heat exchanger in the heat pump unit then transfers the heat from the heated refrigerant gas pipes to the tank where the water is stored. The temperature of the refrigerant drops as the heat has been drawn away and returns to a liquid state, and the cycle begins again.
Solar Hot Water Units:
Solar panels are located, facing north on a roof. The sun heats the water in the panel, which then flows into a storage tank. The tank is usually stored at ground level.
The hot water rises in the storage tank, and this is called thermo-siphoning. This water is then available to the house for use.
The colder water at the bottom of the storage tank travels up to the solar panels and starts heating becoming a continuous cycle.
Disadvantages of solar hot water units compared to heat pump units:
Heat pump hot water units can be placed closer to bathrooms, needing less piping, saving on material costs. Roof-mounted solar hot water system collects the sun. Panels are positioned north on the roof, which can be further away from bathrooms. Strengthening a roof to support the heavier weight of solar panels is also an installation cost.
Solar hot water panels work best in direct sunlight. Problems can occur, including lack of north-facing roof space, trees shading the solar panels, not enough slope to the roof.
These factors can make solar hot water systems installation unachievable. A heat pump installation may be more suitable; they require just a small area at ground level and carried into place. Installation compared to a solar system is a lot cheaper and quicker.
Solar collectors on the roof stand out and can be ugly. Heat pump units can be in back corners out of the way.
Solar panels require cleaning, can be vandalised from rock-throwing and also be damaged from hailstones.
Disadvantages of Heat Pump Hot Water compared to solar hot water units:
A heat pump unit uses a fan and a compressor, so they have the noise of a running fan, comparable to an air condition unit. Recommendations are that you do not place next to bedrooms or the neighbour's bedroom.
A heat pump hot water unit cannot work without power will not heat the water in the storage tank. Water contained in the storage tank is still available for use. However, you will have to wait for the heating process to commence to keep it hot.
If you are in an area with frequent power outages, you may need to invest in a generator to eliminate this problem.
Majority of heat pump models are slower to reheat in cold climates and environments prone to frost. Heat pumps work best when it is warm and humid. However, there are specific models now available on the market which can operate better in colder climates.
It's essential to purchase the right heat pump for your environment.