Heating water is very expensive as it requires a huge amount of energy. It is believed that 18% of domestic energy is used to heat water. In most homes and businesses this energy is generated from fossil fuels – gas and oil. Most modern domestic boilers will run on gas and heat water on demand. But many people still heat their water using electricity which is the most expensive way to heat water.
Domestically, life would be pretty miserable without hot water, and in some manufacturing businesses, hot water is the lifeblood. We can try and save energy by implementing some lifestyle changes to use less hot water (for example, running less full baths, using thermostats on our heating system more efficiently), but in the 21st Century, we all want hot water on tap.
Solar water heating systems are a great way to reduce energy costs associated with heating water. Rather than relying on fossil fuels, there is another option and that is to use solar energy. In the case of solar thermal panels, the sun’s energy is used to heat water which is stored in a hot water tank and drawn on when required. Usually there is an immersion heater or additional boiler for back-up which can heat the water to the temperature you want in the winter or provide additional water in the summer.
As with most things, there are advantages and disadvantages to consider. If you are investigating installing solar thermal panels to heat water for your home or business here are some things to weigh up:
Advantages of Solar Water Heating
- You are using free energy! Solar energy is free and abundant (even in cloudy weather).
- Solar thermal panels take up less space than solar PV panels. This is because usually a typical house would only require 2-3 panels at 2m x 1m each to heat the water in their home. For solar PV panels a typical array might have 10-16 So homes where the roof space is compromised or the majority is in the shade, solar thermal panels may be the most appropriate to install.
- They are efficient. Approximately 80% radiation is turned into heat energy.
- They are cheaper to install than solar PV panels because you only need 2-3 panels. For a typical domestic installation, the cost might be £3400 plus VAT 5%.
- You save money on fuel bills. On an existing gas heating system, the saving could be £65 a year and more with other types of fuel.
- They lower your carbon footprint
- Domestic and commercial properties are entitled to claim the renewable heat incentive. This means that you will be paid for generating your own heat energy regardless of whether you use it all. There’s a user-friendly calculator available which tells you how much you can earn through this scheme. It can be hundreds of pounds a year.
Disadvantages of Solar Water Heating
- Solar thermal panels can only heat water. Solar PV panels, however, generate electricity and some of this electricity can also be used to heat water. So there is more flexibility with solar PV.
- Annual maintenance is recommended. This is because there are a few parts to the system like the pump and antifreeze which need to be checked to ensure that they are performing optimally.
- Usually a new hot water cylinder will need to be installed so space is required to house this.
It is usually a good idea to get a professional installer to view your house to check if your roof is suitable and also to check how efficient your panels will be. There may be too many trees or other types of shading around your house to provide a return on your investment.
Solar water heating can also be combined with solar PV panels if roof space allows. This means that some of the electricity generated from the solar PV panels can be used to top up the solar heated water to the temperature required. This combination of panels is the most efficient way of generating your energy requirements.