Solar Water Heating can save energy and money
Have my neighbours done this?
What is it?
Roof mounted panels that heat the water to be used for your hot taps
What will it save me?
About 50% of your hot water energy costs (about £75 per year)
How do I get it?
This should be installed by a specialist contractor
What does it cost?
Possibly around £3,000 including replacing your existing cylinder (2013)
What are the technical details?
Renewable energy is very desirable because it‘s plentiful and free although it may not be available 24 hours a day. Producing hot water from the sun’s heat has been used for a long time and it's been getting more and more effective but still remains a simple and generally trouble free process.
A solar water heating system consists of a “collector”, preferably on a south facing roof, and a hot water cylinder inside to store the hot water. These are connected by pipes that pump hot water from the collector to the heat store. In most modern systems, the water in the collector contains a refrigerant to prevent it freezing in winter and there‘s a heat exchanger installed in the roof so that contaminated water doesn’t get into the hot water service.
Thermostats are used to control the pump so that the water only circulates when the water in the collector is hot enough. It‘s usual to have a fairly large heat store because it’s possible to obtain a significant amount of hot water from this type of system especially on sunny days, even in the winter.
The collectors can be quite simple things with copper tubes in a back case with a glass top mounted on the roof. However, the most efficient types will include several evacuated tubes connecting together to collect more radiant energy.
Solar hot water systems will usually require a replacement cylinder that has greater capacity than a normal cylinder and 2 heating coils. The solar system connects to the lowest coil to heat most of the content and the upper coil is used to connect the central heating boiler as a top up when necessary. The cylinder should be well insulated with 80mm foam and the pipes should also be insulated.
It is quite possible for solar water heating systems to provide all of the hot water needed for a family for more than 6 months of the year without using other forms of heating, and it's free. There are also potential financial benefits through a government initiative called the Renewable Heat Incentive (RHI).
Although it is possible to make and install DIY homemade solar water heating systems, they are unlikely to be as efficient and effective as professionally manufactured and installed systems so this is best left to the professionals.