How it works - Solar PV explained
Solar photovoltaic (PV) systems are designed for simple installation onto your new or existing roof structure or adjacent building, and will be connected to the consumer unit within the property, thus causing minimal disruption to the infrastructure of your home. When the system is producing electricity it will directly offset the energy being used in the house. In periods when electricity is being produced but not being used, or there is less electricity being used than is being produced, any surplus energy is exported to the national grid for use by others.
We pride ourselves on using only the highest quality components which have proven performance levels, and are backed by strong warranties. Every system specified has at least a 20 year panel performance warranty and is matched with an inverter warranty of at least 5 years. The associated warranties offered may vary depending on the specification chosen by each customer. We believe it is therefore imperative you are comfortable in the specification you have chosen and we would be more than happy to amend or offer alternatives as appropriate.
How does it work?
PV panels are made up of cells which convert solar radiation into electricity. 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.
Solar PV systems consist of two main components.
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.
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. 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.
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. Your property must have an EPC rating of D or above in to qualify for the feed-in- tariff.
PV systems are rated at peak power output. Watts peak (Wp) is the PV peak power in Watts (W) produced at Standard Test Conditions. 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 1kWp grid connected PV system facing within 45° of south and on a roof pitch of 30° to 60° would produce around 750kWh of electrical energy per year. This 1kWp PV array will require around 6-8 m2 of exposed area. A typical three bedroom house uses approximately 3,300kWh per year of electricity, so a typical 1kWp system could provide between 30% and 40% of the total annual electricity requirement.
The size of PV system for you will depend on how much you wish to invest, how much of your electricity you want to generate for yourself, and how much south-facing, un-shaded roof space you have available. Most homeowners install a system of between 1.2 and 3.68kWp, generating between 900-3,500 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. 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.
Generally speaking, you can benefit from economies of scale by installing a larger size PV system; for instance, the cost per kWp of a 3.68kWp system will be substantially less than that for a 1 kWp system. The percentage return on investment from Feed In Tariff (FIT) income and other savings through your electricity bills will also be greater.
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, the inverter is the only component that might need replacing.
Feed In Tariff
On the 1st April 2010 the government launched a new incentive - a "Feed In Tariff" - whereby a guaranteed annual payment will be made to PV system owners for electricity generated and exported for 20 years.
As a result, installing a solar PV system offers you a fantastic investment opportunity, as well as enabling you to future-proof your electricity costs whilst also doing your bit to reduce carbon emissions.
By installing a solar PV system on your home you will get:
• A government-backed, tax-free income stream for 20 years (the 'Feed In Tariff)
• Additional income from electricity fed back to the National Grid (the 'Export Tariff)
• Savings in electricity payments from the clean, renewable electricity generated
• Security against rising electricity prices
• A significant reduction in the amount of carbon your household produces
• A manufacturer's warranty on the power output of PV modules for 20 years (subject to terms).
The government has announced that the Feed In Tariff scheme will run for 20 years with guaranteed income levels over this period which will also rise with inflation. The life span of the PV system is however considerably longer than this - up to 40 years according to some manufacturers - so even when the tariff scheme ends you will carry on benefiting from free electricity for years to come.
The tariff levels confirmed by the Department of Energy & Climate Change for each kilowatt hour (kWh) generated by solar PV systems vary according to the kilowatt peak (kWp) size of the system. Generating tariffs for solar PV are as follows:
4Kwp or less 12.92p
Therefore for a <4kW you will be paid 12.92 pence for every unit of electricity that is generated from the PV system. Additionally, for every surplus energy you generate and export back to the grid you get an additional 4.85 pence per unit. An estimate of generation/saving will be completed during the site survey/quotation stage.
Should you have any further questions please contact ourselves using the Contact us link above