Hot water

What is the most energy efficient type of hot water service?

If you need a new hot water system or if you are looking to replace one then it’s important to be as energy efficient as possible. Hot water systems can often be responsible for 16% of household energy usage and they can last for around 10 years, so choose carefully.

There are a few things to consider before choosing a system, like:

  • What time of the day do you use hot water the most?
  • How much hot water do you need?
  • What do you use hot water for?
  • How much roof space do you have?
  • What type of electricity supply do you have? Green Power? ‘Normal’ brown-coal power? Or maybe your own solar PV roof top array?

You’ve probably heard that gas boosted solar hot water can be very energy efficient, and it’s true. However, many households are now choosing to move away from using natural gas as it is a fossil fuel and the cost of gas continues to rise each year. It is also worth considering the roof space taken up with a solar hot water system, which only heats water, as opposed to using the same roof space for solar panels, which can provide power to other appliances (including an electric hot water system).

In order to utilise renewable energy (either from your own solar array or by purchasing GreenPower or similar from your retailer) we recommend installing an efficient electric hot water system. Heat pumps are the most efficient electric systems to heat water and are ideal for households with higher hot water needs and space for a water storage unit.


Aren’t heat pumps noisy?

The way that a heat pump works is similar to an air-conditioner running ‘reverse-cycle’, and can generate heat. The main difference is that a heat pump heats water rather than air. You have probably come across air-conditioners and have heard the ‘fan-coil’ unit whirring away on a hot day. Heat pump systems are similar and care should be taken when choosing where to locate a heat pump away from bedrooms or places where the noise might disturb others. It’s important to note that the new types of heat pumps are getting quieter so ask a heat pump supplier what your options are.

Which should I choose; solar hot water or solar PV with a heat pump?

It can be a tough choice between solar hot water or solar PV panels. If you are looking for a new hot water system or one that needs replacing then we recommend a heat pump system. We also recommend, if possible, combining this with your own solar power from your roof, or purchasing 100% Green Power if solar isn’t an option for you. For more information about heat pumps we recommend this guide from the Alternative Technology Association.

If you already have an electric hot water system that works then we would suggest not replacing it but simply ensuring that your solar PV system generates enough power to run it, or buying 100% Green Power to cover all your electricity, including your hot water needs as well. You may need to adjust the timer to ensure that you are using power during daylight hours. Some hot water systems require an electrician to do this.