Tim Higgins Solar PV Advice

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Frequently Asked Questions

1, What Is Solar PV

Solar Photovoltaic (PV) is a method of generating electrical power by converting solar radiation into electricity using semiconductors that exhibit the photovoltaic effect.

Solar panels consist of a number of solar cells that produce Direct Current (DC) electricity when exposed to sunlight.

2, Why has Solar PV Technology been developed?

In the long term we can’t rely on fossil fuels as they won’t last forever. The burning of these fuels is damaging our environment and the cost is forever increasing.

The sun produces far more energy than we need and will continue to send us clean, fee energy for several billion years to come.

3, Why should I consider investing in a Solar PV System?

The Government is offering incentives for people to install small scale renewable energy systems. In the case of Solar PV, this is via the “Feed In Tariff” (FIT) scheme.

You are paid for every unit of electricity that you generate and a fixed amount for electricity that is exported back to the network.

This income is tax free, index linked and currently payable over a 20 year period.

In addition the electricity that you generate is free for you to use, so you will make savings  on your electricity bill.

4. How do I get paid for the electricity that my system produces?

This is usually paid to you by your electricity provider by cheque or Direct Debit on a quarterly basis.

5, What are the main parts of a PV Solar system?

The system comprises solar panels, DC to AC inverter, isolators, generation meter, interconnecting cables and an optional monitor.

6, How does a PV Solar System work?

Solar Panels convert sunlight into DC electricity. The inverter then converts this DC electricity to AC electricity. The output from the inverter is connected into your consumer unit or fuse box for use by your appliances and lighting circuits. A generation meter records the amount of electricity that your system is producing. Any electricity not used in the house will be sent back to the grid.

7, What size system can be fitted to my house?

The regulations specify that a domestic system can be up to 4kw peak.

8, How much space is required for the solar panels?

A typical 250 watt solar panel measures 1.0m x 1.7m

Below are the dimensions of 3 typical systems:

2kw system comprising 8 panels will take up an area of 8m x 1.7m = 13.6m²

3kw system comprising 12 panels will take up an area of 6m x 3.4m = 20.4m²

4kw system comprising 16 panels will take up an area of 8m x 3.4m = 27.2m²

Your Solar Energy Surveyor will work out how best to layout the panels on you specific roof.

9, How much electricity will my system produce?

This will depend on the number of panels that can be fitted, the orientation and pitch of the roof(s) and any shading from nearby structures or trees. It is the Solar Energy Surveyors job to calculate the number of Kilowatt hours per year that your system could generate based on the government Standard Assessment Process (SAP) calculation.

10, So what return would I get from having a Solar PV system.

Once the number of Kilowatt hours per year has been determined for your system, the typical returns can be found from a “year on year” calculator.

This calculator will show: the revenue in year 1, the total return over 20 years, the payback time for your system and percentage return in year 1.

As an example the typical returns from a 3.5kw system in year 1, on a south east facing roof with an angle of 30° and little or no shading are as follows:

£438(Generation tariff) + £75(Export Tariff) + £189  (Savings) = £702

11, Is it necessary to have a south facing roof to fit Solar Panels?

Whilst more electricity will be produced from panels fitted to a south facing roof it is still worthwhile fitting panels to roofs facing east or west. The SAP calculation mentioned in the answer to question 4, will quantify this for you

12, Can Solar Panels be fitted to more than one roof.

Most definitely yes. It is quite common to fit 8 panels to both an east facing and a west facing house roof giving 4kw peak in total.

Also there are systems whereby a small number of panels may be fitted to more than 3 roofs. Ask me for more details if this applies.

13, Can Solar panels be installed on an outbuilding or in the garden?

Yes to both. Panels can be fitted to out buildings and may also be fitted to purpose built frames in the garden if there is sufficient space.

14, What is the difference between Monocrystalline and Polycrystalline Solar Panels?

Monocrystalline panels consist of a number of cells grown from a single silicon crystal.

Polycrystalline panels consist of a number of cells grown from multiple silicon crystals.

Typically monocrystalline panels cost more to produce

When comparing the performance of these it is best to refer to individual data sheets.

The performance of all panels will degrade slightly over a period of time, and it should be noted that any panel provided must meet the criteria that its performance should not be degraded by more than 20% over 25 years.

It is likely that the performance of a monocrystalline panel will degrade slightly less than a polycrystalline panel over a given period of time.

15. What happens if I produce more electricity than can be used by my appliances?

Any excess electricity is fed back into the grid to be used by other consumers.

16, What are the effects of shading on solar panels?

Shading to panels from nearby structures and trees is best avoided as it reduces the amount of electricity produced by the system. This is something that is looked at by the Solar Energy Surveyor when assessing the suitability of a roof for installing solar panels. Any shading is taken into account by the government Standard Assessment Procedure (SAP) calculation.

17. Does a Solar PV System work during the winter months?

Yes the system will still produce a useful amount of electricity during the winter months although more will be generated in the summer time due to the greater number of daylight hours and intensity of the sun.

18, Will my TV reception be affected by having solar panels fitted?

It is possible that TV reception could be affected when an aerial is fitted in the loft. In such a case you may have to get the aerial re-sited externally by a qualified technician.

19, Is it necessary to get planning permission to have a Solar PV system installed?

For domestic Installations planning permission is not normally required unless the property is  a listed building, in an area of natural beauty or in a conservation area.  The owner should check with the local authority if in doubt.

20, What is an Energy Performance Certificate (EPC) and why is it required?

Energy performance is a measure of the ability of a house to retain heat.

In order to benefit from the full generation tariff a property must have an EPC certificate rated in Band D or above at the time the Solar System is registered with the Electricity Company.

The Government requires this as it is their aim to save energy first before paying out the “Feed In Tariff”.

If a certificate is not already in existence then the Solar Panel Installer should be able to arrange to issue one. More details can be found on the practical considerations page.

21, What is the difference between Solar PV and Solar Hot water systems?

Solar PV systems produce electricity where as a Solar Hot Water Systems provides hot water for washing and showering.

A Solar Hot Water system consists of a set of Solar Collectors installed on the roof or high up on a wall and a storage cylinder. The sun warms up a liquid that flows through the solar collectors, this liquid is then used to heat up the water in the storage cylinder. For occasions when more hot water is required than can be generated from the Solar Hot water System, a backup of more traditional methods is used to heat the water.

22, How much does a Solar PV system cost?

In order to provide a quotation, it will be necessary to carry out a survey to find out if the property is suitable for Solar PV and to work out how many panels can be fitted.

23, Should I inform my Insurance Company if I have Solar Panels installed?

Yes, I would advise anyone that is having Solar Panels fitted to inform their Insurance Company. The Installation Company will be able to provide you with all the necessary technical information required by the Insurance Company.

24, What is the Microgeneration Certification Scheme?

For Products:

The MCS is an internationally recognised quality assurance scheme which demonstrates the quality and reliability of approved products by satisfying rigorous and tested standards.

Product certification involves type testing of products and an assessment of the manufacturing processes, materials, procedures and staff training.

For Installation:

The MCS is an internationally recognised quality assurance scheme which demonstrates to customers that the installation company is committed to meeting rigorous and tested standards. The MCS provides a mark of competency and demonstrates to customers that the installation company can install to the highest quality every time. Installer certification entails assessing the supply, design, installation, set-to-work and commissioning of renewable microgeneration technologies.

25, What is REAL?

The Renewable Energy Assurance Ltd. (REAL) Consumer Code was set up by the Renewable Energy Association. Their aim is to guarantee a high quality experience for consumers wishing to buy or lease small-scale energy generation systems for their homes. The REAL logo is a sign that the Installation Company has agreed to abide by the high standards set out in the Consumer Code.

26, Do I need a new consumer unit or fuse box if I have a system fitted?

No, this is not usually necessary as a separate isolating switch is provided for the Solar PV System. However if you have an older fuse box this may be a good opportunity to upgrade to the latest 17th edition consumer unit for safety reasons. Your surveyor will be able to advise on this.

27, How do I know how much electricity is being generated by my system.

The cumulative amount of Electricity generated will be displayed on your Generation Meter, at certain times you will have to provide a reading from this to the organisation that will be paying you the Generation Tariff.

As an option you may like to have a separate monitoring device which displays the amount of electricity be generated at any given time. This will help you decide when is the best time to turn on appliances such as a washing machine to benefit from the free electricity that you are generating.

Some monitors will also give information on your electricity consumption giving you the motivation to use less.

A monitor will help you get the best out of your Solar PV system and make greater savings on electricity.

28, What is meant by voltage optimisation?

A voltage optimisation device reduces the incoming AC mains voltage from approximately 240 V AC down to 220 V AC. Many appliances such as fridges, freezers, washing machines, tumble driers, dishwashers, televisions and other electrical appliances will use less energy at this lower voltage. Installation of a Voltage optimiser can save you up to 10% on your electricity bill. This is entirely separate to a Solar PV system but can be fitted at the same time if required.

29, What happens to the solar energy system if I sell my house?

Although the system belongs to you it would not make sense to take it with you if you move house because apart from the de-installation and re-commissioning charges it would constitute a new installation for which you are likely to receive a lower “Feed in Tariff”.

Instead the agreement to provide the “Feed In Tariff” can be transferred to the new owner along with any outstanding guarantee.

30, How can some companies offer a Solar PV System free of Charge?

Companies offering to provide a Solar PV System free of charge are effectively renting a space on your roof.

They benefit by receiving the Generation and Export Tariff whilst you benefit from free electricity during the day.

Should you wish to sell your house in future you need to be sure that any potential new owner can easily obtain a mortgage on the property as the Solar PV System is owned by another party.

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