What does PV mean?
PV is an abbreviation of ‘photovoltaic’, which is a word composed of the Greek photo for light and volt an electrical unit named after Alessandro Volta, who was a pioneer in the study of electricity. So, photovoltaics can literally be translated as light-electricity; which is exactly what photovoltaic materials and devices do - they convert light energy to electricity.
How do photovoltaic systems work?
Light hits the photovoltaic cells and is converted to electricity. An inverter converts this electricity from direct to alternating current, for use in the home. When the system is producing more power than is needed the excess is exported to the National Grid. At night, or at any time where the system is not producing enough power to meet all the household’s requirement power is imported from the grid as normal.
What are the components of a photovoltaic (PV) system?
A standard PV system is comprised of a number of PV panels; roof or ground mounting frame; an inverter that converts the DC (direct current) produced by the panels into AC (alternating current) for use in the house; isolators to ensure the system can be turned off safely and a generation meter to show how much electricity the system has produced
Does a PV system need batteries?
No, the system is connected to the national grid, so at night or whenever when the system is not generating enough energy, electricity is bought from a utility company as usual. Any excess electricity generated during the day is sold back to the utility company. Therefore, there is no need to store electricity and no need for batteries.
Ardenham Energy has experience of designing off grid and battery backup systems, however these are generally only required for properties which are not attached to the grid or where protection from power cuts is essential. Batteries add significantly to the cost of a system so would only be specified on request.
Will we continue to have power during a power cut?
No. Any grid connected PV system is designed to switch off in the event of a power cut. This is a legal requirement and is a safety feature designed to stop electricity leaking on to the National Grid and harming workmen trying to restore the fault.
What do kW, kWh and kWp mean?
A kW or kilowatt is a thousand watts and is a unit of power.
A kWh is the amount of energy used, when a kW of power works for one hour. A kWh is what is normally referred to as a ‘unit’ on your electricity bill.
kWp is the kilowatt ‘peak’ of the system. This is a standardised test for all PV panels regardless of manufacturer to ensure that the values listed are capable of comparison. The test conditions for module performance are generally rated under Standard Test Conditions (STC): irradiance of 1,000 W/m2, a module temperature at 250C and a solar spectrum of AM 1.5
Simply put, the system size is rated in kWp and its output in kWh.
How many panels will I need?
According to the Energy Saving Trust, the average 3 bedroom house consumes 3,500 units of electricity (kWh) a year. However, every household is different, so it is best to look back over your old bills or contact your supplier to find out how much electricity your family uses a year. Ardenham Energy can then design a system to best suit your needs.
How long do PV systems last?
A well designed and installed PV system will operate for well over 20 years. A PV panel has no moving parts and can last more than 30 years. It is estimated that performance will decrease by under 1% per year, which would mean that in 50 years they’d still be 60% efficient. All of the panels Ardenham Energy use come with a 20+ year performance warranty and all of our work is guaranteed for 2 years.
What maintenance does a PV system need?
Solar photovoltaic systems are silent in operation and require no maintenance. Although the build up of dirt can affect system performance, the panels are generally self-cleansing in the rain. If easily accessible, the panels can be cleaned with either a hose or, if possible, soapy water and a non abrasive brush once a year.
How long does installation take?
From the time you agree your order Ardenham Energy should be able to install your system within two weeks. The actual installation normally only takes a day for the average sized domestic property and involves very little disruption for you.
What about the weather in the UK?
Surprisingly, this is not too much of a problem! PV systems depend on the intensity of light, not direct sunlight. So even in more northerly and cloudier countries such as the UK, there is ample diffuse light when it’s overcast for the system to produce electricity. Solar panels are actually happy in cold climates and for example on a sunny (but cold) day in January it can produce the same amount of electricity per sunlight hours as in July.
What is the optimum orientation and pitch for panels in the UK?
The ideal orientation for a PV system in the northern hemisphere is due south, with a tilt from the horizontal equal to the latitude minus approximately 10-15 degrees. So 30 degrees is an optimal tilt in Southern England, while it is almost 40 degrees in the north of Scotland. If the optimum angle is not possible, over 90% of the maximum annual energy can still be achieved at 10 degree or 50 degree tilts.
Does shading matter?
Shading is the number one enemy of PV systems! Even minor shading can result in significant loss of energy from the system. Simply put, this is because the panel with the most shading determines the operating current of the whole string of panels to which it is connected. So even if only one panel out of 10 is shaded, it is the same as if all 10 were shaded. This is why it is so important to carry out a site survey and identify any potential shading hazards before designing the system.
Ardenham Energy is able to offer innovative solutions such as module inverters to overcome some of the problems presented by heavily shaded sites. So even if you feel your site might not be ideal, get in touch and we may be able to help.
What is the payback period on a solar PV system?
Please see the pricing section of our website for details on payback.
How can I benefit from the Feed-In Tariff?
Please look at our Feed-In Tariff page for further details on the tariff and how it could benefit you.
Do I need planning permission?
In considering planning, some local authorities require planning permission to allow you to fit a PV system, especially in conservation areas or on listed buildings. Always check with your local authority about planning issues before you have a system installed. Obtaining retrospective planning permission can be difficult and costly. Currently the whole aspect of permitted development is being reviewed for micro renewables.
Is VAT payable?
Prices are based on residential VAT rates of 5%. For commercial projects VAT of 20% applies
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If you have any further questions, please contact Ardenham Energy on 0800 369 8986 or email us at info@ardenhamenergy.co.uk
