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A Guide To Solar Photovoltaics
Contents
2
3
what’s the big idea
4
how does solar pv work?
6
the key factors to consider
9
pv systems available
12
feed-in tariffs
14
connecting to the grid
15
the team
What’s the big idea?
photovoltaic: Producing a voltage when exposed to radiant energy (especially light.) The sun provides an immense source of free renewable energy. The use of Photovoltaic (PV) cells gives us the opportunity to harness this energy and turn it into useable electricity. Solar PV Tech use the latest technology, up to date software and expertise to maximize the yield of any Solar PV system. If you have looked at a range of renewable technologies and are thinking about installing Solar PV, this guide aims to give you an understanding of everything involved. Beyond this Solar PV Tech can offer you free, impartial and expert advice.
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How does Solar PV work?
Photovoltaic is the direct conversion of light into electricity at the atomic level. Some materials exhibit a property known as the photoelectric effect that causes them to absorb photons of light and release electrons. When these free electrons are captured, an electric current results and this can be used as power. PV cells range in size from a few cm2, like those found on calculators to systems of hundreds of square metres making up huge arrays in solar fields. The modules we are now used to seeing on homes use a thin layer of semi-conducting material, normally silicon, encased between sheets of glass or plastic. They have no moving parts and very significantly do not emit any Carbon Dioxide when generating electricity, as opposed to fossil fuel driven power stations.
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“Significantly (PV
cells) so not emit any
Carbon Dioxide when
generating electricity�
When exposed to sunlight the semi conducting materials cause electrons in the materials atoms to be released. These freed electrons flow through the material to produce a direct current (DC). If the installation is designed to provide power for your home or to push back onto the grid then this DC current needs to be converted into a stable alternating current (AC). To achieve this, the DC current is directed via cabling to an Inverter.
The inverter converts the direct current to alternating current and sends it back to your homes main fuse box.
PV Modules
Although it may sound complex, accommodating the wiring for a Solar PV installation can be done with minimal disruption to your homes fittings or decoration.
Appliances
Inverter
Fuse Box National Grid
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Key Factors To Consider...
Is PV suitable for my home?
Solar photovoltaic systems can be mounted to almost any existing roof provided it is strong enough to take the additional weight. In some cases a structural survey and then potentially strengthening works may have to be carried out.
Planning Permission
In England, changes to regulations with respect to renewable technology mean that most solar installations fall within permitted development rights and therefore do not require planning permission. There are exceptions and this does not apply to commercial installations. Exceptions include installations on Listed Buildings, buildings in Conservation Areas, World Heritage Sites and Areas of Outstanding Natural Beauty. Properties where permitted development rights have been used up will also need to apply. We will, of course, give you advice on the requirements and can deal with an application on your behalf. It is also important to inform your building insurance company of your installation as they may need to note it as a material fact on your policy. This shouldn’t increase your premiums but check first with your insurance company.
Orientation
For the optimum performance a PV array would ideally face South and be pitched at an angle of 30-40 degrees from the horizontal. However, East or West facing roofs with a pitch of between 20-50 degrees can also be viable and can provide up to 85% of the optimal orientation. North facing arrays are not recommended.
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Maintenance Once a photovoltaic array is set up it can last for decades, with almost no running costs. Most renewable energy sources, such as wind and hydro, rely upon turbines to turn generators. Photovoltaic systems, however, have no moving parts, greatly reducing the risk of expensive breakdowns. Solar PV modules have a very long lifespan and the modules Solar PV Tech use all come with a 25 year manufacturers warranty. PV systems require little maintenance as rainwater should keep the module surface sufficiently clean. Occasional additional cleaning may be required from time to time, particularly if the panels are located near trees (sap & birds). Solar PV Tech suggest an annual clean and system check over, which we can arrange.
Warranties
System warranties may vary. Module manufacturers performance warranties will normally be 80% of output for 25 years. It is important to realise that the product guarantee for all modules is only 5 years. Solar PV Tech only use manufacturers who have been producing modules for over 25 years. This ensures that the panels are tried and tested and will last the length of the FIT. Inverter warranties are generally 5 years but in many instances this can be extended to ten or even twenty years. Solar PV Tech has a ten year insurance backed warranty on our work. It is important to use high quality components to achieve long term value for money, high performance and durability. 7
Continued... Cost
Despite a high initial cost, Solar PV is a sound investment. Long-term savings can easily offset the initial costs of installing a system. Once in place, the system will continue to generate energy with very little added expense.
Roof Layout
PV arrays are made up of modules of around 1m x 1.6m and as such can be arranged to fit on most roof layouts. With regards to size, a roof area of around 20m2 could accommodate a system able to generate 50% of an average households electricity requirement.
Shading
Shading should be avoided where possible. Shading even on one module (panel) acts as a resister to the whole system and can significantly reduce the systems output. However, shading between 10am and 4pm could have a serious impact on performance and would question the viability of an installation. It should be noted though that with good system design and planning many shading issues can be overcome. In a situation where shading cannot be avoided, the use of micro-inverters can vastly reduce its impact.Â
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PV Systems available...
Commercial Commercial installations are eligible for FIT tariffs and the financial incentives are even greater.
tems Commercial Sys
• Turn redundant roof space into a source of revenue. • Offset investment against corporation tax (consult your accountant for other tax incentives). • Utilise the majority of the electricity generated due to your daytime demand. • Interest free loans from the Carbon Trust. • Systems have long term guarantees and insignificant maintenance costs. • Be seen to be green. 9
PV Systems available cont...
On Roof Systems
On-Roof
An On- Roof Solar PV system is mounted on framework attached above an existing roof. Roof anchors sit beneath the slate/tile and fix to the rafters. A rail attaches to the anchors with the modules clamped to them. The gap between roof and panel creates the optimum environment for energy production. As air passes underneath, it cools the modules for optimum efficiency.Â
In-Roof
In-Roof Systems
An In-Roof system takes the place of slates or tiles and creates a less intrusive look. It requires the same roof criteria as an OnRoof system only slates/tiles are removed to make space for the modules, which of course also keeps the weather out. Flashing around the array joins it to the slates/tiles to make a completely watertight roof.
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stems Free Standing Sy
4IG0H% ER
H T OUTPU
ms Tracker Syste
Free Standing
Where a pitched roof isn’t available, a free standing system can be installed on a flat roof or ground mounted. On flat roofs manufactured module stands can be ballasted at the optimum pitch and orientation without affecting the integrity of the roof. Ground mounted systems use similar module stands and can also be positioned with the perfect orientation and pitch.
Tracker A Solar PV Tracker is an array mounted on moving framework. A Tracker System follows the suns path from East to West, therefore optimising system performance. Some trackers even change inclination depending on the time of the year to make sure the array is perpendicular to the sun throughout its daily course. Tracker systems can yield up to 40% more energy when compared to a stationary system
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Feed In Tariffs... Clean Energy Cash Back Scheme & Feed In Tariffs (FITs) In April 2010 the UK government introduced the Clean Energy Cash Back Scheme as a financial incentive to encourage the uptake of renewable energy technologies. The Clean Energy Cash Back Scheme put in place FITs as a financial support mechanism for people undertaking renewable energy. The government need to encourage the uptake of such technology to help deliver on the 2020 renewable energy targets. The scheme pays you an amount for every unit of power (kilo Watt hour/kWh) that your system generates. The amount paid per unit is dependant on the size of the system. For domestic systems, which are mostly under 4kW retro-fitted on homes this amount is 43.3p/unit. It is important to note that this is TAX FREE and indexed linked for 25 years. It is also dependent on the point at which you join the scheme, the Feed In Tariff is set to drop year by year from April 2012. Currently there’s no smart meter to ascertain where the electricity goes after generation. A contract is drawn up with your energy supplier stating that 50% is used within your home and 50% is sold back to the national grid at 3p/unit. This is a hypothetical figure. In a situation where your demand far exceeds the total generation of the system, you still obtain the 3p/unit for half the systems generation, even though you aren’t exported anything.
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The amount paid per
unit is dependant on the size of the system. For
most domestic systems
retro-fitted on homes this amount is 43.3p/unit.
Then there is the money you save on your electricity bill. As you are generating your own electricity you will have to import far less. Your meter reading will be lower meaning your bill will be less. With energy prices set to rise, this element will become more and more valuable.Â
Each unit of electricity that is surplus to the power requirements of your home is eligible for an export tariff which is in the region of 3p/unit depending on your energy provider. Therefore, (assuming that your FIT is 43.3p/unit) for every unit of energy exported to the grid there would be a total payment of 46.3p.
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Connecting to the Grid
The Basics Electrical connection must comply with the G83/1 regulations. The connection must be approved by the local District Network Operator (DNO) which is Western Power Distribution (WPD) in the South West. Upon surveying a property, Solar PV Tech will enquire to the DNO on your behalf. All being well they will give permission for the system to be installed. Once the system is up and running we will provide the DNO with a copy of the BS7671 electrical installation certificate, inverter G83/1 certificate, Small Scale Embedded Generator (SSEG) connection application form and a schematic of the installed system. The DNO will then issue a connection approval letter and we will forward this to you for your records.
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For a more indepth explaination of anything involved or for any queries please don’t hesitate to contact us. Office: 01769 560715 www.solarpvtech.com
the team
Director - Max May
Max May max@solarpvtech.com 07967 313 777
Communications Manager - Leila Dinari
Leila Dinari leila@solarpvtech.com 07813 127 120
Director - Lewis Ames
Lewis Ames lewis@solarpvtech.com 07886 676 828
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switch on to a greener future Office: 01769 560715 www.solarpvtech.com
Max May max@solarpvtech.com 07967 313 777
Leila Dinari leila@solarpvtech.com 07813 127 120
Lewis Ames lewis@solarpvtech.com 07886 676 828