Design Considerations For Solar Thermal Systems

Do I have space for a larger hot water cylinder?

A solar thermal system requires a dedicated cylinder, with a purpose-designed coil, to allow maximum heat transfer of renewable energy into the stored water.

Solar coils are much bigger than traditional boiler coils because the hot water travelling through the coil is at a lower temperature. Therefore a greater surface area is required to transfer the heat to the stored water.

It is also important that the temperature differential between the top and the bottom of the cylinder is maximised so the solar thermal system can always contribute towards the heating demand of the property. To facilitate this, the design of a solar thermal cylinder is larger and taller than a standard hot water cylinder

Is a solar thermal system compatible with my existing heating system?

Most conventional boilers and renewable heating options are compatible with a solar thermal water heating systems and can easily be installed to create a hybrid heating system. Combination boilers however, which don’t require a separate hot water cylinder, would be unsuitable.

The size of system (the number of collectors and water cylinder capacity) required, is determined by the number of occupants and their daily hot water requirements at 60°C. As a general rule of thumb, 1m² of solar collector surface area is required for each person living in a property; so for an average 3-4 bedroom house 2 collectors would be required. As the average person uses approximately 50 litres of hot water each day, a standard 4 bedroom house would require a 200 litre hot water cylinder.

Orientation & Angle of Inclination

A south-facing roof with an incline of 30° is the optimal location for solar water heating; but a solar thermal system can be installed at any angle, whether wall mounted or on a flat roof. On a south-east or south-west facing roof the output may be up to 10% lower and up to 20% lower on east and west facing roofs. On an east-west facing property it is advisable to place a solar collector on each side of the roof to maximise the amount of solar irradiation received throughout the day.

The angle of inclination for a solar thermal system is the angle between the roof / ground and the solar collector. As the angle of the sun relative to the horizon varies from summer and winter the optimum angle for a solar collector is between 20° and 45°. The Firebird Envirosol™ range of solar collectors however have been tested at various tilt angles and are effective at angles between 15° and 75°.

Wind Loads & Shading

The Firebird Envirosol™ solar collectors and fixing bracket systems are designed to meet the requirements of all UK wind zones. However in high wind load areas, for example excessive heights or very exposed areas, additional fixing brackets may be required.

To minimise the effect of wind load on the solar collectors, it is recommended that they are not installed within 0.5 metres of the roof edge, ride, eaves or projections such as parapets, chimneys or dormer windows.

Obstructions which result in shading can considerably reduce the performance of a solar thermal system. When carrying out the site survey it is essential that consideration is given to the proposed location of the collectors and any likely obstructions.

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Technical data for Envirosol Solar Thermal Systems..

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Envirosol Solar Thermal

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Warranty

Firebird Envirosol™ solar collectors are covered by a 5-year warranty with all other solar components covered by a 2-year warranty. For further information, please contact us.

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