Q. How do Solar PV systems work?
A. Solar PV panels are made up of cells which convert solar radiation into electricity to run appliances and lighting. The PV cell consists of one or two layers of semi-conducting materials, usually silicon, and when light shines on the cell it creates an electric field across its layers, causing electricity to flow. The amount of electrical energy produced depends on the amount of light that falls on the PV panels. Importantly, PV requires only daylight – not direct sunlight – to generate electricity although the output from your PV system will vary with the intensity of the light.
Filsol solar PV systems consist of two main components:
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PV panels – also known as PV modules, these contain a series of PV cells which convert light into electricity. To give a desired electrical power output (measured in Watts) a number of panels are connected together to form a PV array.
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DC/AC Inverter – this converts the direct current (DC) electricity generated by the panels into alternating current (AC) electricity which matches the building’s mains electrical grid supply. If the building is not connected to the National Grid the inverter is usually replaced with a battery bank to store the electricity generated.
In a grid-connected home, the electrical energy produced is either used directly in the home, or sold back to your electricity supplier. At night electricity from the grid is supplied in the normal way.
PV systems generate no greenhouse gases, and a typical domestic 2kWp system can save approximately 1.5 tonnes of carbon dioxide emissions per year.
Q. When is a house suitable for a PV system?
A. Filsol solar PV systems can be tailored to suit most homes. The roof or facade on which the PV panels are installed must face within 90 degrees of South. Shading caused by trees or other buildings should be avoided as this will result in the output of the system decreasing, even if the shading is there for only a part of the day.
Q. How much energy does a PV system produce?
A. PV systems are rated at peak power output which is usually quoted at Standard Test Conditions (STC). Watts peak (Wp) is the PV peak power in Watts (W) produced at STC. These conditions are rarely achieved in practice and so the Wp rating of a PV system is the potential maximum output power. The actual output depends on solar radiation levels which vary considerably according to the time of day, time of year and location.
Based on a typical installation in a UK home, a well designed 1.5kWp grid connected PV system facing within 45° of south and on a roof pitch of 30° to 60° would produce around 1,200kWh of electrical energy per year. This 1.5kWp PV array will require around 10-12 m² of exposed area and use a DC/AC inverter of 1,100W.
A typical three bedroom house uses approximately 3,300kWh per year of electricity (Source: Energy Saving Trust), so a typical 1.5kWp system could provide between 30 and 40% of the total electricity requirements.
Q. What size of PV system do I need?
A. The size of PV system for you will depend on how much money you wish to invest, how much of your electricity you want to generate for yourself, and how much south-facing, unshaded roof space you have available.
Most homeowners install a system of between 1.2 and 3.5kWp, generating between 900-3,000 kWh per year. It is not necessary to meet all your home’s electricity needs through your PV system as you will still be connected to the national grid and be able to receive ‘top-up’ electricity in the usual way.
Q. How much does a Filsol PV system cost?
A. The cost of a fully-installed PV system can vary considerably depending on how easy or difficult it is to access the roof, and the technology or product that you choose. Most homeowners install a system of between 1.2 and 3.5kWp, and typically the costs for equipment and full installation will be in the region of £5,000 and £6,300 per kWp.
Generally speaking, you can benefit from economies of scale by installing a larger size PV system; for instance, the cost per kWp of a 3.5kWp system will be substantially less than for a 1.2kWp system. The percentage return on investment from Feed In Tariff (FIT) income and other savings through your electricity bills will also be greater.
Please contact us to discuss the optimum system for your circumstances and we will be happy to provide you with a detailed quotation.
Q. What about maintenance?
A. Grid-connected systems require very little maintenance, have no moving parts and are silent in operation. Maintenance is generally limited to ensuring that the panels are kept relatively clean (although the rain will largely do this for you) and that shade from the trees has not become a problem. During the lifetime of the system, you may well need to replace the inverter at a cost of approximately £600-900 for a typical domestic system.
Should you have any further questions please email enquiries@filsol.co.uk and we will respond as soon as possible.
