Frequently Asked Questions

A selection of ‘FAQs’ to bring you the facts about Natural Generation’s services and wider renewable energy issues...

• Solar PV

  • Does Shade affect the performance of a PV system?
    • Yes, solar PV is affected by shading. If one module becomes shaded it can potentially reduce the output of the whole system because of the way the modules are connected (in series). This is why design and analysis of your site is so important. Natural Generation carry out shading analysis on ALL sites with leading software packages such as PVSOL.
  • Can I still have PV on a Shaded site?
    • We have installed some systems which have certain shading issues (chimneys/dormers/trees). The effect of shading on an array of panels can be minimised with the use of an inverter with two tracking points (MPPT) or by using voltage optimiser devices. We will recommend the best system for you, or tell you the site is unsuitable.
  • How is the system fitted to my roof?
    • It depends on the roof covering. In typical domestic installations, we use slate and tile brackets which are fixed to the rafters. We remove the slate or tile, fit the bracket (and lead flashing for a slate roof), then grind out the slate/tile to ensure it fits tightly and lays flat around the bracket. Rail is then fitted to the brackets and the modules clamped to the rail at the correct positions on the module.
  • What is an inverter and where is the best place for it?
    • An inverter converts direct current (DC) electricity from the solar PV panels to alternating current (AC) electricity so that it can be used in the home or exported to the grid. The inverter needs to be located in a cool place to ensure it runs at its maximum efficiency. Some inverters are IP55 rated and therefore suitable for outside installations.
  • Can I still have PV panels on an East/West facing roof?
    • Yes, this will have a reduced output of approximately 14% compared to a south facing roof but will give a wider spread of power throughout the day, rather than all the max power being centred around a few hours either side of midday. This may coincide better with your demand profile, i.e. more power during early mornings and late afternoon/evening.
  • Who pays the Feed-In Tariff (FIT)?
    • The FIT provider doesn’t have to be your normal electricity provider. The FIT will be paid quarterly once you have supplied your first meter reading. You will need to get a FIT application form, either paper or online. We recommend Good Energy, a 100% renewable electricity company. Please see http://www.goodenergy.co.uk/feedintariff for more information.
  • Do I need planning permission to install solar panels?
    • Planning permission is not generally required but may be necessary if your property is listed or in a conservation area. Planning officers are being encouraged to accept green energy installations whenever appropriate. For more information please see http://www.planningportal.gov.uk/permission/commonprojects/solarpanels/.
  • Is the equipment and workmanship guaranteed?
    • Most modules have guarantee 90% output after 10 years and 80% output after 20 years, the full term of the guarantee. We only use module manufacturers who we think will continue to trade for those lengths of time. The inverter typically has a 5-year warranty.

      All of our solar PV installations are covered by a 5-year parts and labour warranty. We also register our installations with The Deposit and Workmanship Warranty Insurance (DAWWI) Scheme, which guarantees warranties should we cease trading. Please see http://www.realassurance.org.uk/members/insurance for more info.

  • Is there any maintenance required?
    • Solar PV is generally maintenance-free. The panels may require occasional cleaning if they become very soiled; however most panels are self-cleaning when positioned at angles of more than 15°. The electrical side of the system should be included as part of a normal electrical inspection and test.
  • What happens if I have a power cut?
    • The inverter works by monitoring your grid voltage so that you maximise the amount of energy that you use from the system. If you have a power cut, the inverter cannot measure your grid voltage and will shut down until power is resumed. If this is the case, the inverter will automatically restart.
  • How does generation differ over the year?
    • A solar PV system produces the majority of its annual energy (73%) between April and September. November through to January will produce less than 10% of the annual energy.
  • Will I still receive an electricity bill?
    • You will still require power from the grid when the sun is not shining and when your demand exceeds your generation. You will therefore still receive an electricity bill, but we would expect it to reduce.
  • Do solar PV systems still work in dull conditions?
    • Solar PV panels will still generate in duller and more overcast conditions. The percentage of peak output generated in these conditions depends on the amount of cloud cover and the time of year. Some panel models are optimised to perform better in these conditions. Performance in Devon and Cornwall is generally better than the rest of the country due to higher levels of sunshine.
  • How does heat affect the performance of solar PV?
    • Solar PV panels work more efficiently when they are cool. When the panel temperature rises, in times of bright sunshine for example, efficiency reduces by approximately 0.5% per °C increase above 20°C. If a panel reaches 40°C for example, you will lose 10% of the system’s peak output.
  • How do I know which system is right for me?
    • A Natural Generation engineer will visit your home to discuss your individual needs and carry out an initial survey. This survey will include looking at your roof structure, its angle and orientation, assessing any shading impacts and determining the electrical supply and setup. From this we will be able to prepare shading assessments, system design and quotation.

• Solar Hot Water (Solar Thermal)

  • How do I know which system is right for me?
    • Natural Generation’s design engineers will visit your home to discuss your individual needs and carry out an initial survey. This survey will include looking at your roof structure, its orientation, your hot water cylinder, your current heating system and your home's physical layout. From this we will be able to prepare a system design and quotation.
  • Does Natural Generation Ltd offer a choice of panels or represent just one supplier?
    • Our only criterion is to fit the best equipment for the job. We are an independent accredited installer of solar hot water panels and can offer products from a range of suppliers to suit the requirements of each individual customer.
  • Is there a grant available for a solar hot water system?
    • The Renewable Heat Premium Payment (RHPP) provides £300 (non-repayable) towards the capital cost of a solar hot water system. It is administered by the Energy Saving Trust. For more information, visit their website or see http://www.rhincentive.co.uk/RHI/regulation/premium/.
  • Do I need planning permission to install solar panels?
    • Planning permission is not generally required but may be necessary if your property is listed or in a conservation area. Planning officers are being encouraged to accept renewable energy installations whenever appropriate. For more information please see http://www.planningportal.gov.uk/permission/commonprojects/solarpanels/.
  • Can I install a solar system with a combination boiler?
    • Most older combination boilers will not accept pre-heated water so are not suitable, but many manufacturers are now developing solar-compatible boilers. Please contact us for advice if you have a combination system.
  • Will I need to re-plumb my whole house?
    • The only part of the existing plumbing that has to be changed is the hot water cylinder. The replacement hot water cylinder must have a solar coil incorporated. In swimming pool heating applications a heat exchanger must be added to the filtration pipe-work.
  • Are solar hot water systems suited to the climate in Devon and Cornwall?
    • Correctly sized solar hot water systems can provide around 60% of the domestic hot water for a property. This will vary depending on the patterns of hot water use. Businesses that have a high hot water demand in the summer – such as the tourism sector – can provide the majority of their needs from a solar hot water system.
  • Where is the best place to position solar panels?
    • A South-facing system at an angle of 30° - 35° will provide maximum solar gain. Even systems installed as on East/West roofs are completely viable with a reduction in output of less than 15% when compared to South. Mounting solar hot water panels at a shallower angle will increase solar gain in the summer; winter gain will be improved by increasing the angle.

• Wind Turbines

  • Do wind turbines interfere with electrical equipment?
    • No. Happily, there’s no interference with electrical equipment from wind turbines.
  • Will a wind turbine affect the value of my own or my neighbour's property?
    • There is recent evidence that installing wind turbine or solar PV system adds value to your property. Your neighbour's property price should not be affected by the installation of a wind turbine. We will always ensure that a turbine is sited in locations which will not adversely affect neighbouring properties.
  • How efficient are wind turbines?
    • The efficiency of wind turbines is often misquoted by anti-wind campaigners. While it is true that the efficiency statistics appear low, the fact that the fuel (wind) is free means that the more important factors are the annual energy production and lifetime of the machine.
  • How do I know which turbine is right for me?
    • We will first undertake a desktop survey and then visit your site to see if it is in a suitable location to undertake a survey and discuss the options with you.
  • What is the expected lifetime of a wind turbine?
    • The wind turbines that Natural Generation Ltd supply and install have a design life of 25 years.
  • Does a turbine require any maintenance?
    • Owning a wind turbine is much like owning and running a car – annual maintenance is required to ensure continued and efficient operation. Natural Generation can help you with this.
  • Do I need planning permission?
    • Planning permission is required for wind turbines that we supply and install. The good news is that Planning Policy Statement 22 requires planners to encourage renewable energy where suitable. See http://www.planningportal.gov.uk/permission/commonprojects/windturbines/ for more information.
  • How close to our property can a turbine be located?
    • We would recommend the turbine is located at least 80m from the nearest occupied building.
  • How much space do I need for a wind turbine?
    • The turbine requires a footprint on the ground for raising and lowering which equates to approximately 2.5 times the height of the tower.
  • Can I and should I insure the wind turbine?
    • As with any investment, it is important to insure the turbine in case of an unforeseen unfortunate event. Naturesave offer a renewable energy insurance policy, see http://www.naturesave.co.uk/

• Heat Pumps

  • Is there a grant available for a heat pump system?
    • The Renewable Heat Premium Payment (RHPP) provides a non-repayable grant of £850 towards the capital cost of an air-source heat pump and £1250 for a ground-source heat pump. It is administered by the Energy Saving Trust. For more information, see http://www.energysavingtrust.org.uk/Professional-resources/Funding-and-finance/Renewable-Heat-Incentive or http://www.rhincentive.co.uk/RHI/regulation/premium/.
  • What is the expected lifetime of a heat pump?
    • Water-water type heat pumps are expected to far outlast even the best quality boiler. They should operate for more than 20 years and with minimal maintenance. Air source systems are usually exposed to the elements and have a slightly harder life, but should still last longer than a conventional boiler.
  • Why is underfloor heating coupled with a heat pump so highly rated?
    • The lower the target temperature of heated water, the better the heat pump operating efficiency. Standard radiators can require temperatures as high as 80°C to operate effectively; this is hotter than the temperature a heat pump can achieve. It is often necessary to increase the area of radiators to be able to obtain the maximum working temperatures of 50°C from a heat pump. However, if the water temperature can be further reduced, to around 40°C or less, there will be considerable energy savings.
  • What heat can a heat pump provide?
    • A heat pump can generally heat water up to around 55°C. This is usually adequate for hot water and also room heating. It is vital to understand that the hotter the water, the lower the energy efficiency, so running at a lower temperature will save a lot of energy.

      The following figures for a typical ground source heat pump system illustrate this:

      • Water heated to 55°C = 2.4 COP (Coefficient of Performance)
      • Water heated to 45°C = 3.2 COP
      • Water heated to 35°C = 4.0 COP
  • What is the Coefficient of Performance (COP)?
    • COP is the energy efficiency ratio. A COP of '4' means you get an output of 4 kW of heat for 1kW of electricity supplied to the heat pump.