Solar Panels Feasibility

Is Solar Panel Technology suitable for my Property?

If you are considering installing a solar hot water heating system there are a few important points to consider. Solar hot water heating systems use heat from the sun to work alongside your conventional water heater. The technology is well developed with a large choice of equipment to suit many applications.

Both types of solar hot water heating, flat plate solar panels and solar evacuated tubes, work in the same way. Radiated light is used to heat up a surface, usually selectively coated with a substance and in a way to collect light and convert it into heat efficiently. The selectively coated surface is called an absorber.

The absorber transfers heat to an array of pipes fixed inside the collector, which carries a non freezing heat exchange fluid. The heated fluid is then pumped to the hot water cylinder which in turn heats the contents. For more information on how eco hometec can help you to incorporate a Solar Panel Hot Water & Heating system in your new build please submit your Building plans here.

For domestic solar hot water heating there are four main components:

Solar panels or collectors - are fitted to your roof. They collect heat from the sun's radiation.
A heat transfer system - uses the collected heat to heat water.
Hot water cylinder - stores the hot water that is heated during the day and supplies it for use later.
Solar differential pump & controller - automatically controls the pump & system temperatures.

'A' Frame & Roof situated Solar Panel Installations

Solar Panel Installation

An independent survey carried out on behalf of the Department of Trade and Industry surveyed 700 solar hot water heating systems installed in the UK.

Among the conclusions were:

Domestic solar hot water heating systems perform well in all parts of Britain although slightly better in southern areas compared with the north of England and Scotland.
Systems using selective surface flat panels perform as well as those using evacuated tubes.
Most systems perform as well now as they did when they were new.

Solar water heating can be used in the home or for larger applications, such as swimming pools. You will need 3-4 square metres of southeast to southwest facing roof receiving direct sunlight for the main part of the day for a domestic system. You may also need space to locate an additional water cylinder if required.

Choosing a system suitable to your needs requires consideration of a range of factors, including the area of south facing roof, the existing water heating system (e.g. some combi boilers aren't suitable).

Locations & Climate - will it work in the UK?

Solar energy availability in the UK is much greater than most people imagine. Indeed the UK receives on average approximately 65% of the annual radiation experienced by the South of Spain and even 55% of that received on the Equator. The solar energy that we experience is accounted for by approximately 40% direct radiation (received when it is sunny) and some 60% diffuse, or scattered, radiation (received on cloudy days).

Monthly distribution of annual solar radiation received on a plane inclined at 30 degrees facing South in the South of England

Distribution of annual Solar Radiation

The solar radiation received on a plane, facing due south, which is inclined at 30 degrees (this is a typical inclination for solar collectors situated on a pitched roof in the UK, varies from about 900 kWh/m³ per year in the North of the UK to approximately 1,300 kWh/m³ per year in the South West. Whilst the highest amounts of monthly solar radiation are obviously experienced in the summer months, there is enough radiation coming from the sun in spring, autumn and winter to make a very useful contribution to a household's energy needs. A total of 1350 hours of sunshine per year are experienced on average in the UK according to the MET Office. Areas in the north of the UK have about 1250 hours per year while in the south the sunshine could provide up to 1470 hours per annum. There are 8 months when the sun is out for more than 100 hours per month. Four of these months the sun is out for well over 150 hours per month. There are only two months in the year when the sunshine is less than 50 hours per month.

The contribution that a solar water heating system can make toward a households energy requirements with a properly sized solar system can he expected to provide:

80 - 90% of all summer hot water needs
40 - 50% of spring and autumn requirements
10 - 15% of a household's winter water heating needs

UK annual solar irradiation (kw/sq m) Source: Solar Trade Association

Solar Radiation Map of the UK

Solar water heating can provide almost all of your hot water during the summer months and about 50% year round. The average domestic system reduces CO₂ by around 350kg - 400kg per year, depending on the fuel replaced.

Roof situated & 'A' Frame Solar Panel Installations

Installation of Solar Panels

Positioning the collectors:

Positioning the collectors is important for optimum performance. Collectors should ideally be mounted at an angle of between 30 degrees and 60 degrees on a south facing roof that is not shaded by overhanging trees buildings or structures.

Inclination of solar panels:

The inclination of the solar collector plane to horizontal plays an important role in the collection of solar radiation. The solar panels work best and are at their most efficient when the sun rays fall perpendicular to the collector's glass. Ideally the panels should sit at an angle of 30 to 40 degrees and face south. When this is impossible due to site constraints then two arrays can be used on opposing west and east roofs.

Good results can be obtained by splitting the collector array on East/West elevations but this should only be used when it is not possible to have a mainly southerly position for the collectors.

Collectors can also be wall mounted vertically however their performance will be less in the summer, when sun is highest and slightly better in winter when the sun is at its lowest. If roof space is an issue they can be mounted on the ground or flat roofs on an 'A' frame.

Do I need Planning Permission for my Solar Panels?

In England, changes to permitted development rights for micro generation technologies introduced on 6th April 2008 have lifted the requirements for planning permission for most solar hot water heating installations. Roof mounted and stand-alone solar hot water heating systems can now be installed in most dwellings, as long as they respect certain size criteria. Exceptions apply for Listed Buildings, and buildings in Conservation Areas and World Heritage Sites.

In Wales, Scotland and Northern Ireland, the devolved governments are currently all considering changes to their legislation on permitted developments, to facilitate installations of micro generation technologies, including solar hot water heating. Legislation is expected in all three countries during 2009. Until then, householders in Wales, Scotland and Northern Ireland must consult with their local authority regarding planning permission.

Permitted development rights

The General Permitted Development Order (GPDO) grants rights to carry out certain limited forms of development on the home, without the need to apply for planning permission. The scope of the GPDO in England now extends to the following technologies:

Solar PV and solar thermal (roof mounted) Permitted unless:

The Solar Panels when installed protrude more than 200mm.
They would be placed on the principal elevation facing onto or visible from the highway in buildings in Conservation Areas and World Heritage Sites.

Solar PV and solar thermal (stand alone) Permitted unless:

More than 4 metres in height.
Installed less than 5 metres away from any boundary.
Above a maximum area of array of 9m².
Situated within any part of the curtilage of the dwelling house or would be visible from the highway in Conservations Areas and World Heritage Sites.

Please browse our website for more information about eco hometec and our range of Eco Heating products including Solar Panel Technology then click here to submit your plans or contact us on Freephone 0800 8620278 to speak to one of our team or e-mail us on sales@eco-hometec.co.uk.