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Solar photovoltaic (electric)

Energy from the sun has been used for thousands of years , this energy has been used in three main ways and it is important to distinguish between these three types.

Passive heat: this being the natural heat generated by the sun. this can be taken into account when building a property.
Solar thermal: using the sun’s heat to provide hot water.
Photovoltaic (PV): using the sun’s energy to generate electricity. PV requires only daylight, not direct sunlight, to produce electricity.
 

        

How PV works.
Photovoltaic systems use cells to convert radiation from the sun into electricity. The cell is made from one or two layers of a semi-conducting material, usually silicon. When the cell is introduced to a light source it creates an electrical field across these layers causing electricity to flow. The higher the light intensity the more electricity is generated. There are three main types of solar PV cells:
Monochrystalline: made of thin slices of silicon cut from a single silicon crystal. This type of cell typically has an efficiency of about 15%.
Polycrystalline: made of thin slices of silicon cut from a block of silicon crystals. This type of cell typically has an efficiency of about 12%.
Thin film: made from a base sheet of glass or metal covered in a very thin layer of semi-conductor atoms. This type of cell typically has an efficiency of about 7%.
 
These cells are connected together into modules which are then linked together. The amount of modules required will depend on the power level needed within a property. If the property has mains electricity, any surplus power the system produces can be exported back into the national grid. Alternately, the excess power can be used, where required, to charge batteries.
PV modules come in a variety of shapes and colours, ranging from grey ‘solar tiles’ that replace roof tiles, blue/black panels and transparent cells that can be used on conservatries and glass to provide shading as well as power. There are also a variety of ways in which these can be mounted, ranging from vertical, flat or at an angle, although an angle is generally used.
 

Applications.

There are many ways of using Solar PV, ranging from torches calculators, battery chargers to integrated systems for providing power to buildings. Solar PV systems can be used on mainly on buildings with a roof or wall that faces within 90deg of south, see diagram, as long as no other buildings or trees over shadow it. If the panels are shaded then the power output will be reduced. It is also possible to mount the panel array on a frame in , for example, a garden. When fitted to a roof, the weight of the system must be taken into account as the panel arrays are often very heavy. In some cases the roof may need to be strengthened.
 
Domestic installations.
The physical size of a solar PV array varies from property to property depending on a number of factors.
1: the amount of power required from the system.
2: the type of Photovoltaic (PV) cell used in the modules.
3: how much roof space is available for mounting the array.
4: your budget.
A typical system usually generates around 1.5-2KWp (kilowatts peek), enough to provide approximately 40% of a families annual supply (assuming gas is used for the main heating supply and there are no other energy saving measures). To produce this level of power an array would typically cover 10-15msq of roof area.
 
Planning considerations.
In some cases, you will require planning permission for a Solar PV system to be fitted. This is especially true in conservation areas or on listed buildings. It is always prudent to check with your local authority about planning issues before you have a system installed.

 

Costs and Maintenance.
The cost of a Solar PV (electric) system will vary depending on a number of factors.
1: the size and power of the system required. 2: the type of cell used.3: the building the system is to be mounted.
An average domestic system can cost anything from £4000 (per kwp installed), or more excluding vat. With an average domestic system being 1.5-2kwp, the cost (based on £4000 per kwp) would be £6000-8000, or more. Please note that these are NOT exact figures and will vary. Solar PV tiles and roof integrated panels cost more than the normal panels. If you are having major roof repairs it may be worth considering solar PV tiles as they will offset the cost of replacement roof tiles.
 
Several groups offer Grants to help with the costs of installing Solar PV systems. grant levels are set at a maximum of £3000 per KWp installed, up to a maximum limit of £15,000. this is subject to an overall 50% limit of the installed cost exclusive of vat. Grants are only available on systems producing over 0.5kwp. Before a grant application is made you must have taken certain energy saving measures within your property. These are as follows;
Low energy lighting must be installed in all main areas/rooms (if not through out) of your property.
270mm or more of mineral wool insulation( or equivalent ) must be installed to the whole of the loft space of your property.
Cavity wall insulation must be installed in all of the appropriate walls of your property.
Basic heating controls must be installed for the central heating system including thermostats in all main rooms/areas and a programmer or timer.
Here at A D BREDEN LTD we can, if necessary, install the required measures (cavity wall insulation being contracted out) prior to a grant application being made, although the costs of installing these measures will vary from property to property. Our ‘Free Low Energy Survey’ will help you assess your needs and as a follow up you will receive a detailed ‘no obligation quotation’. The measures listed above are insisted upon so as to ensure that basic energy savings are already being made and to help ensure that the system installed will work to your best advantage.
 
Systems connected to the national grid require little maintenance, basically keeping the panels clean and free from shade. The wiring and system components will need to be inspected periodically by a qualified engineer. Stand alone systems (i.e., not connected to the national grid) need further maintenance on extra components such as batteries.
 

 

 

                    

The image right shows a basic view of a Grid connected system where surplus power is
sold back’ to your supplier resulting in further reduced electricity costs. The amount saved
will vary from property to property

 

Solar photovoltaic (electric) panels work by using the suns energy/light to create AC electricity. This is then converted from AC into a DC current by an Inverter for use in the home. Surplus energy the system generates can be stored in batteries (not shown) and/or sold back to the electricity supplier. PV systems require good daylight –not direct daylight – to generate electricity. The greater the intensity of daylight the more energy is produced.
 

                                       

                                Contact Information           

                                                        Telephone                      01483 811452
 
                                                         FAX                                   01483 813663
 
                                                        Postal address              Unit 12 The Elms, Glaziers Lane, Normandy, Guildford, GU3 2DF
 
                                                        Electronic mail               General Information: Sales Inquiries: adbreden@btconnect.com