FAQ’s
Q. What is solar photo voltaics or PV ?
A. Solar Photovoltaic’s (PV) is a system which generates electricity from sunlight (photo meaning light, voltaic referring to electricity). Sunlight is free and endless, the energy generated is completely free and the systems have no carbon output, making them truly renewable.
Q. How does solar PV work?
A: Daylight hits the photovoltaic cells and is converted to clean electricity. The inverter converts the electricity from direct to alternating current, for use in the home. When the solar energy system is producing more power than is needed it is exported to the grid. At night, power is imported from the grid in the normal way.
Q. How will I know if my house is suitable for solar PV panels?
A. A Chiltern Solar consultant will take you through a series of checklist questions which will determine whether your property is initially suitable for PV such as orientation of roof, amount of roof space available, access for scaffolding, planning issues etc. This will include a basic desk-top survey using mapping software to estimate how much roof space you have, giving an indication of the price of the system. At your request, a Chiltern Solar surveyor will visit your home to confirm the size of the system, take details and dimensions of your property and identify any issues that could impact on the installation. The installer who will complete the job will then conduct one more brief visit to confirm the survey findings and provide the official quotation for the installation.
Q. Will I have enough sunlight for Solar PV?
A photovoltaic (PV) system needs unobstructed access to the sun’s rays for most or all of the day. Climate is not really a concern, because PV systems are relatively unaffected by severe weather. In fact, some PV modules actually work better in colder weather. Most PV modules are angled to catch the sun’s rays, so any snow that collects on them usually melts quickly. There is thus enough sunlight to make solar energy systems useful and effective nearly everywhere in the United Kingdom.
Q. How big a Solar Energy system will I need?
A: The size of solar system you need depends on several factors such as how much electricity or hot water or space heat you use, how much sunshine is available where you are, the size of your roof, and how much you’re willing to invest. After talking through your exact needs we will be well placed to recommend the size of system you use.
Q. Where should the Solar PV panels be placed?
A. Ideally, they should be on a pitch of between 30 and 60 degrees (which is why roofs are ideal) facing due south so as to maximise the sunlight falling on them. South East to South West orientations are still excellent. As the orientation is rotated round to East or West the system might be expect to generate about 15% less electricity than a south facing array, but there is still a good return to be made.
Q. What does a site survey involve?
A. The survey will involve a comprehensive check of the roof for suitability of Solar Panels. The surveyor will also check the electrical distribution board and all other aspects of the installation such as location of PV panels, orientation, and access for scaffolding, loft access etc.
Q. How much roof space will I need?
A. On average a 1 kW of Solar PV panels covers approximately 7.5m². So for a small system, 2kWp, a minimum of 15 m² will be required. Because the panels are a set size, a good rectangular area of around 5m by 3m is ideal as a minimum surface area requirement.
Q. How do I guarantee the quality of my Solar PV product and installation?
A. In order to ensure you are getting a recognized quality and workmanship, there is a mark of accreditation called the Microgeneration Certification Scheme (MCS) which covers all renewable energy installers and equipment. Both the system and the installer should be MCS accredited as it is a requirement to claim the Feed in Tariff, plus it gives you added peace of mind for your investment. The pv panels supplied by Chiltern Solar all hold the MCS accreditation as are the installers who carry out all the installations.
Chiltern Solar are also members of the REAL Assurance Scheme was set up by the Renewable Energy Association. It aims to guarantee a high quality experience for consumers wishing to buy or lease small generation units for their home, for a community building or for a small business. REAL membership is a sign that the supplier has agreed to abide by the high standards set out in their consumer code.
Q. Will I need planning permission?
A. In most cases, no. Solar PV is classed as permitted development provided it falls within certain criteria. However, it is always a good idea to check with your local authority and get written confirmation. Chiltern Solar will work with your local planning authority on your behalf to obtain written confirmation of a permitted development as part of our customer service.
There are situations where permitted development rules don’t apply, namely if the building is listed or in a Conservation Area, National Park or Area of Outstanding Natural Beauty.
In this case it is likely that you will have to seek planning permission but it will depend on the type of installation i.e. where the panels will be located on the property e.g. for conservation areas planning will sometimes allow PV panels if they are not facing the road. Chiltern solar will be able to offer advice and help you through all aspects of your planning enquiry.
Q. Will the Solar PV panels still work in the winter time?
A: Yes. Solar panel suppliers have enhanced the efficiency of solar power systems to the extent that it is now a very viable option even in cloudier climates. The important thing to bear in mind is that solar power depends on intensity of light, not necessarily direct sunlight. So even when it’s overcast, your solar panels will be producing clean electricity to help power your home.
Q What happens if there is a power cut?
A: Photovoltaic systems for homes are entirely grid connected. If there is a power cut your system is automatically switched off. This is a safety measure designed to stop electricity leaking on to the national grid and to protect individuals who may be working to restore the power supply.
Q. Does the system store electricity and do I need batteries?
A: No, the system is connected to the national grid. In the night, when the cells are not generating energy, electricity is bought from the utility company in the normal way. Any excess electricity generated during the day, for example when you are at work, is sold back to the utility company.Batteries are only required if you want a truly off-grid solution and independence from any power cuts that might occur. They are also required if you own a property which is not attached to the grid in order that power produced during the day can be stored for use in the evening. Batteries add significant costs to a solar system so are normally only offered on specific request.
Q. How much Solar Energy do I need?
A: According to the Energy Saving Trust, the average 3 bedroom house consumes 3,300 units of electricity (kWh) a year (cooking and heating using non electric supply). However, we always recommend that you look at your last few bills or call your electricity supplier to find out how many units you consume, you can then compare this to the output of the system we recommend.
Q. What if I produce more Solar Energy than I need?
A: Whenever your panels are producing more electricity than your home is using, it will flow back into the grid for other homes to use. As long as you have an arrangement with your energy company, you’ll be paid for this power so you can be sure your energy bills will be even less and none of your clean, green electricity will be wasted.
Q. What does Solar Panel energy efficiency mean?
A: Energy conversion efficiency is an expression of the amount of energy produced in proportion to the amount of energy consumed, or available to a device. The sun produces a lot of energy in a wide light spectrum, but we have so far learned to capture only small portions of that spectrum and convert them to electricity using photovoltaic’s. So, today’s commercial PV systems are about 7% to 17% efficient, which might seem low. And many PV systems degrade a little bit (lose efficiency) each year upon prolonged exposure to sunlight. For comparison, a typical fossil fuel generator has an efficiency of about 28%.
Q. How can the energy outputs on different solar panels be estimated?
A: The specification sheets for all panel manufacturerers will give the size dimensions and the maximum expected power for each individual panel type. With this in mind and assuming a reasonable tilt, orientation and system efficiency, a rule of thumb estimate for the UK is for every 1kW of maximum production, it can be estimated that 800kWh of energy will be produced over an average year.
Q. How do Solar Panels perform at different angles and orientations?
A: If the optimum angle is not achievable, over 90% of the maximum annual energy can still be achieved at 10 degree and 50 degree tilts. South-facing vertical facades generate around 70% of the maximum.
Q. What are the effects of shade?
A: Shading is critical. Minor shading can result in significant loss of energy. This is because the cell with the lowest illumination determines the operating current of the series string in which it is connected. This is one of the areas covered in the survey carried out before any installation. We use modern arrays that can bypass the affected diodes to minimise shade effects; but these effects must still be considered.
If shading is unavoidable, or poor light is expected on a regular basis, then we will modify our designs and possibly even the type of cell we use. This can obviously only be taken on a case by case scenario.
Q. How can the energy benefits of my Solar PV system be maximised.
A: Orientation, shading and the temperature of the PV elements all impact on their output and must be considered at the design stage. Of course, the more energy efficient the building, the greater the overall benefit of the PV cells.
Q. How much can I save on my electricity bills?
A. You could expect to use about half of the electricity you generate. In this case you would use about 850 units for a south-facing 2.0kWp system. This generated electricity replaces what you would buy at about 12.5 pence per unit from your supplier, so you would save around £106 per year. For larger systems this saving would be proportionally higher.
Q. How much carbon will I save?
A. The generated units from a 2.0kWp system will replace around 1700 grid units, saving about 0.75 tonnes of CO2 per year. The figure for the 2.7kWp system is 1.0 tonne and for the 3.5kWp system is 1.3 tonnes.
Q. What is the feed in tariff?
A. The Feed in Tariff (FiT) is a Government initiative which offers a payment for electricity generated from renewable sources, on a price per unit basis. All of solar PV systems will attract the maximum 43.3 pence per kilowatt hour for retrofit installations. You will also gain an extra 3.1 pence for every generated unit you do not use and instead export to the national grid. All FIT payments are tax free.
Q How does the feed in tariff work?
A. Assuming a south-facing roof with an optimum pitch of 30 degrees and no shading.
A 2kWp system will generate approximately 1717 KWh of electricity, based on SAP 2005 calculation.
You will get paid for 1717 units x at 43.3p / KWh and receive £743 per year.
It will be assumed that you will export 50% of the units back to the grid at 3.1p to give you a further £26. per year
You will be importing less electricity (assume 50%) from the grid and based on the average rate of electricity being 12p KWh you will save a further 103 per year.
Your total benefit will be £872 per year Tax Free
A 2.7 kWp system could be expected to earn £1,200 and a 3.5kWp system £1500 total yearly benefit.
Q. How long will the feed in tariff last?
A. The FIT incentive is planned to last for 25 years from when the installation is completed. You will benefit from the rate at which the feed in tariff was running when you had your installation even if the government decide to reduce it in the coming years. The FIT will track inflation and the retail price index, so it will increase year on year.
Q. How is the feed in tariff paid?
Your FiT payments will be paid quarterly on the basis of your generation meter readings. You will be paid the tariff amount (43.3p per kilowatt hour) for every generated unit. Your export tariff (3.1p) will be assumed as half of this meter reading unless you have an export meter installed, in which case you will be paid the export tariff on the basis of that reading. Both the generation and export tariffs will increase in line with inflation, tracking the Retail Price Index.
Q. Who pays the feed in tariff?
A. The Energy companies are obliged to find solutions to help us all in the UK reduce our carbon output. As part of this obligation they will pay for your Feed in Tariff. As a result, there will be a very slight increase in everyone’s energy bills, but this makes generating free electricity all the more attractive.
Q. Will my system be MCS accredited?
A. All of our PV installers are MCS accredited as are the panels that will be fitted. You will therefore be eligible to register for the Feed in Tariff.
Q. How can I connect my Solar PV system to the national grid?
A: Connecting a PV system to the distribution network will require permission from the Distribution Network Operator (DNO). The DNOs in the UK have different policies when it comes to connecting PV systems to their networks, and so different rates will be paid for exported electricity. We will make the necessary arrangements for grid connection. Currently the trend amongst suppliers is not to install export meters but to pay a fixed amount per kilowatt peak installed. This means that you will be rewarded for the electricity generated from your system even when you use it in your home - potentially doubling its value. Most of the big utilities will buy back the energy you generate for the same price as they sell it to you.
Q How long will my Solar PV system take to be installed.
A. While this depends on the size of the system and the complexity of the project a typical installation should take no more than 2 to 3 days. From the point of signing the agreement and paying a 25% deposit installations are planned to take place between 2- 4 weeks time. This will be subject to product and material availability.
Q. How do I apply for the feed in tariff?
A. The products supplied and your installation will all be accredited by the Microgeneration Certification Scheme (MCS) which ensures eligibility for the Feed in Tariff incentive. You will be required to provide your chosen energy supplier with your details, a copy of both the MCS number and final invoice and the initial generation meter readings. Chiltern Solar will compile this data for you and the installer will provide you with a completed application form on completion of the installation. All you will have to do is enter the details of the bank you would like the FiT to be paid into, then sign and return to it the energy supplier.
Q. What is net metering?
A: Net metering is a policy that allows homeowners to receive the full retail value for the electricity that their solar energy system produces. The term net metering refers to the method of accounting for the photovoltaic (PV) system’s electricity production. Net metering allows homeowners with PV systems to use any excess electricity they produce to offset their electric bill. As the homeowner’s PV system produces electricity, the kilowatts are first used for any electric appliances in the home. If the PV system produces more electricity than the homeowner needs, the extra kilowatts are fed into the utility grid.
Q. Do the Solar Panels need maintenance?
A: Solar photovoltaic systems are silent in operation, have no moving parts and require no maintenance. Solar thermal systems have a few moving parts (inside the pump) but these are virtually maintenance free, you may need to replace the anti-freeze in a solar thermal system after about five years. Most of the time the rain will keep the modules clean. However, a build up of dirt can affect system performance. The degree of soiling will depend on the location but usually dust accumulation and self-cleaning reach a steady state after a few weeks if the array tilt is at least 15 degrees. In extreme cases dust may cause a power reduction of about 10%. At low tilts horizontal glazing bars can trap debris which could lead to shading of part of the array. The design of the system should aim to minimise uneven soiling. The modules can be cleaned with either a hose or, if possible, soapy water and a non abrasive brush.
Speak to Chiltern Solar for a regular cleaning service and quotation.
Q. What guarantees are there for Solar PV equipment and installation?
A. The PV panels carry a 5 year workmanship warranty and a power output warranty of 80% after 25 years which means that if anything goes wrong with the system over 5 years they will be covered under the warranty process for replacement or repair.
Likewise the power warranty guarantees continual performance throughout a 25 year period and if at any time performance drops below the 80% of the maximum capacity, the panels will be covered under the warranty process.
The inverter carries a 5 year warranty with the option of an extended 20 year warranty at additional cost. The installation of the PV is covered under a 12 month warranty. There is also an opportunity for PV customers to extend this warranty after the 12 month period.
Q. How long do Solar PV systems last?
A: A well-designed and maintained PV system will operate for more than 20 years. The PV module, with no moving parts, has an expected lifetime exceeding 30 years. The most common cause of problems is the failure of electronic parts included in the Balance of Systems (BOS) – the controller, inverter, and protection components. These are all covered in a 5 year warranty.
Q. What happens if something goes wrong?
A: All panels come with a 20+ year performance warranty so in the unlikely event that you experience problems, the supplier should be on hand to diagnose your problem and if necessary, arrange a home visit to ensure that everything is working as it should be. The installation comes with a 12 year warranty so you can be sure your service will be of the highest standard.
Q. Is a deposit required?
Yes, a deposit of 25% of the overall project price will be taken at the point of agreement as confirmation of the customer’s intention to go ahead with the proposed works.
A further advanced payment of 25% of the overall project price will also be required after the seven day cooling off period has expired This will be no more than three weeks before the agreed installation date and used for work under the agreement for the specific project for example purchasing goods, in this case PV solar panels.
Chiltern Solar install throughout Buckinghamshire, Hertfordshire, Bedfordshire, Berkshire, South Oxfordshire and London. Including; Watford, St Albans, Berkhampstead, High Wycombe, Aylesbury, Amersham, Chesham, Slough, The Chalfonts, Gerrards Cross, Luton, Milton Keynes, Bedford and all surrounding towns and villages.
