Solar Water Heating

Solar hot water

Solar water heating Harnesses free power from the sun and can provide around one third of the hot water requirements for an average family home.

Whilst they work best on warm sunny days, modern solar systems will heat up water all year around, even on cloudy, overcast days in winter.

The system does not replace a conventional water heater. Instead, it works alongside your system, thereby reducing your energy requirements for heating water, reducing your home's carbon footprint by around one third of a ton per year and reducing your water heating bill by around one third.

Solar Hot Water Heating systems range in price from a few pounds, for an enthusiastic DIYer building a basic system, up to several thousand pounds for a professionally installed system.

Understand the components needed within a solar thermal system

What does Solar Water Heating provide?

Solar Water Heating provides hot tap water for the home. By itself it does not provide hot enough for radiator heating throughout a home, although the solar collector will still be of benefit by reducing the amount of energy required to heat it to the higher temperatures.

During the summer months, most solar hot water systems will provide enough hot water for the average family for washing and cleaning. During spring and autumn, it will provide some of the water required, although you will require additional heating alongside the solar system.

During the winter, a solar hot water system will only provide minimal heating, although on sunny days the system will still produce a useful amount of heat.

Can solar water heating be used to heat up my house?

By itself, a solar hot water system does not heat up the water to a high enough temperature to be used in traditional radiator heating.

However, solar hot water heating can provide a high enough temperature for underfloor water heating systems, and this combination is now becoming a popular choice for people specifying and building their own homes.

Even where a Solar Water Heating system cannot provide all the heat required for radiator heating, it can be used to reduce your overall heating bill by providing warm water to be heated to higher temperatures rather than cold.

How does Solar Water Heating work?

For a domestic solar hot water heating system, there are three main components:

  • One or more solar panels (often called 'Solar Collectors') are fitted to your roof.
  • A heat transfer system to use the collected heat to heat water.
  • A hot water cylinder to store the hot water that is heated during the day and supplies it for use later.

Contrary to popular belief, most solar panels don't actually contain water. Instead, they contain a special fluid that can heat up very quickly inside the solar panel. This heat is then transferred into the water in the heat transfer system.

There are two types of solar panels that can be used for heating water:

Flat Plate Collectors

A flat plate collector comprises of an absorber plate with a transparent cover to collect the sun's heat.

Flat plate systems are comparatively cheap to buy, but are not the most efficient solar collectors on the market, typically providing 30-50% efficiency and only really providing useful heat in direct sunlight.

Evacuated Tube Systems

Evacuated Tube Systems comprise of a row of glass tubes that each contain an absorber plate feeding into a manifold which transports the heated fluids.

Evacuated Tube Systems are used in most new installations and can provide 50-70% efficiency. They can also provide a good amount of heat in overcast conditions.

Is Solar Water Heating suitable for my home?

Solar hot water systems are not suitable for every home. To be effective, an average home will need 3-4 square meters of roof - facing south-east to south-west - which receives direct sunlight for the main part of the day.

The height of the sun, and it's path across the sky, varies throughout the year, and it is important that your proposed roof area does not get shaded at different times of the year.

To find out how much sun is available at your location, use the solar irradiance calculator on the Solar electricity Handbook website.

Alternative Uses for Solar Water Heating

The other use for solar water heating is to provide warm water to a site which has no facilities at all: allotments, garden sheds, remote workshops and campsites can all benefit from simple solar water heating systems for providing basic warm-water washing facilities where there is no electricity or even where there is no running water supply at all!

These systems tend to be much simpler and cheaper than household installations: the simplest is a 'solar shower' black pouch with a tap at the bottom costing less than £10 and providing ample hot water for camping, or at your garden shed.

Solar Water Heating is also popular for heating swimming pools, both permanent installations and temporary garden paddling and swimming pools installed for a few weeks during the summer.

Are there any grants available?

Unfortunately due to the cut backs in the UK, there are no grants available at this time.

For other countries it is worth checking to see if grants are available.

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Solar Electricity Handbook

Solar Book

The Solar Electricity Handbook is a simple, practical guide to using electric solar panels and designing and installing photovoltaic PV systems.

The Solar Electricity Handbook assumes no previous knowledge of solar power systems, it explains how panels work, how they can be used and explains the steps you need to take to successfully design and install a electric photovoltaic system from scratch.