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Solar Thermal

Solar Thermal Systems (Solar Hot Water Systems) are one of the most efficient and cost effective renewable energy sources available today. Heating the hot water in your home is by far the greatest drain on the energy you are paying for – in fact it can be as much as 43% (see below)

With energy prices spiralling, the cost of running your home is becoming more & more expensive every year, but a Solar Thermal System can provide up to 70% of your homes annual water needs for free. In the summer months 100% of your hot water requirements could be met purely by the system (see below)


How it works

The sun's rays contain energy, a Solar Thermal System uses solar collectors (evacuated tubes) to collect this energy. This is then used to heat a fluid (glycol), a pump then circulates this fluid and transfers the heat to your hot water cylinder.

Solar House

The Evacuated Tubes

Evacuated Tube

At Radley we prefer to use Evacuated Tubes rather than Flat Plate collectors. They have a greater surface area and are more efficient in the UK climate. They have a faster response to intermittent sunlight and more effective in adverse weather conditions.

Solar Controller / Pumping Station

Pumping Station is the heart of the system and the Controller is the brains as this manages the whole system during the day. This enables you to control your hot water much the same as a conventional heating programmer. The Pumping Station and Controller come as a self contained unit and are normally installed in your roof space. However the Controller can be separated and mounted elsewhere in your home as it contains an easy to read display which allows you to monitor the temperature of the Evacuated Tubes on your roof, and the temperature in the top and bottom of your hot water cylinder.


Changing the existing hot water cylinder is a required part of the installation, this is because a Solar Thermal System requires a dedicated Solar Cylinder - having two coils rather than one as found in a conventional hot water tank.

Temperature Sensors

There are two sensors in the system, a collector sensor and a cylinder sensor, both are continually monitored by the control panel. If the temperature sensor in the cylinder detects the collector has not collected enough energy to heat the water to the right temperature, the supplementary heat source tops up the water temperature so that it comes out of the taps to the required temperature.

Other Installed Components

Apart from the main components, a Solar Thermal System also comes with a surge protector in case the collector is struck by lightning. An Air Separator and an expansion vessel which is used to take up the increase in volume in the solar circuit when the pump is turned off but the collectors are still generating (e.g. on very sunny days).

What is the Renewable Heat Incentive?

Solar Hot Water

As well as transforming the sun’s energy into hot water, Solar Thermal technology has the power to earn and save you money. Under the government-funded Renewable Heat Incentive (RHI), technologies including Solar Thermal Panels will earn payments for every unit of heat generated.

The RHI scheme will be launched in two phases. Payments for non-domestic systems started on Monday 28th November 2011 with those for domestic Solar Thermal systems due to start in October 2012. An additional Renewable Heat Incentive (RHI) premium payment of £300 is also available to domestic customers from 1st August 2011.