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Frequently Asked Questions

Is a solar PV or a wind energy system suitable for me?

Inherent Energy will advise you whether or not your site is suitable for either a solar thermal, solar PV or wind system. We will explain where we would propose to site the system, and the electricity output you can expect to gain from our recommended system.

If your site is unsuitable for a PV or wind system, we will advise you of this: we would never try to sell a system that is inappropriate. We do not believe it is in our interests to do this, as we need satisfied customers in order to stay in business. In order to give you additional reassurance regarding our professional conduct, we are members of the Renewable Energy Association’s consumer assurance scheme ‘REAL’ – please see the Real Assurance Scheme for more details.

Where can I put a PV system?

When you first contact us we will ask for some information which will enable us to advise you on the best location for a PV system. The smallest PV systems (1 kWp) generally require at least 8 m2 of un shaded, southerly facing roof area.

South facing is optimum, but the system can be mounted anywhere from West facing through to East facing. The optimum angle for a system is 30 to 45 degrees from the horizontal in order to maximise output, however an angle from 5 to 60 degrees is possible, with a small reduction in output. Shading of even only a small part of a solar PV system will significantly reduce its output. This is due to the electrical connections being in series so that shading of a small part can reduce the output from the whole system.

Where can I put a wind system?

A wind turbine should be at least some distance from any obstruction such as buildings or trees. (As a rule of thumb, the distance should be 10 x the height of the obstruction). The prevailing wind direction is generally south west, so it is particularly important that the land is open to this side of the wind turbine.

What is solar energy?

Solar energy is energy radiated by the sun and which reaches the earth’s surface as heat (infra red) or light rays (UV and visible light). Energy from the sun has been harnessed for thousands of years.

We use this energy in three main ways and when talking about solar energy it is important to distinguish between these three types:

  • Passive heat

    This is the heat that we receive from the sun naturally. This can be taken into account in the design of buildings so that less additional heating is required.

  • Solar thermal

    Where we use the sun's heat to provide hot water for homes or swimming pools. We cover this topic in another fact sheet: solar water heating.

  • Photovoltaics (PV)

    Uses energy from the sun to create electricity to run appliances and lighting. PV requires only daylight - not direct sunlight - to generate electricity.

How does PV technology work?

Photovoltaic systems use cells to convert solar radiation into electricity. The PV cell consists of one or two layers of a semiconducting material, usually silicon. When light shines on the cell it creates an electric field across the layers, causing electricity to flow. The greater the intensity of the light, the greater the flow of electricity.

The three main types of solar cells are:

  • Monocrystalline

    Made from thin slices cut from a single crystal of silicon.

  • Polycrystalline

    Made from thin slices cut from a block of silicon crystals.

  • Thin Film

    Made from a very thin layer of semiconductor atoms deposited on a glass or metal base.

Individual PV cells are connected together to form a module. Modules are then linked and sized to meet a particular load (need). The result is a PV array which supplies power to the building it is fitted on. If the building has mains electricity, any excess electricity can be exported to the national grid.

Alternatively, when demand is high, extra electricity can be purchased from the national grid through the utility companies. Where there is no mains supply, PV arrays can be used to charge batteries.

PV arrays now come in a variety of shapes and colours, ranging from grey 'solar tiles' that look like roof tiles, to panels and transparent cells that you can use on conservatories and glass to provide shading as well as generating electricity.

What are the applications for PV?

There are many applications for PV, ranging from calculators, solar torches and battery chargers to integrated systems for homes, offices, factories and public buildings. You can use PV systems for a building with a roof or wall that faces within 90 degrees of south, as long as no other buildings or large trees overshadow it.

If your roof surface is in shadow for parts of the day, the output of the system decreases. Another consideration is that your roof must also be strong enough to hold the significant weight of the panels, especially if they are going to be placed on top of existing tiles.

What size of a PV array is required to provide electricity for a typical home?

The size of a PV array required to provide electricity for a typical home varies, depending on a number of issues; how much power you need, the type of cell used, roof space available and budget. Typical systems are generally around 1.5-2kWp (kilowatts peak), enough to provide almost half of the average family's annual supply (assuming gas is used for heating requirements and there are no energy efficiency savings). This array would typically cover 10-15m2 of roof area. Solar PV installations should always be carried out by a trained and experienced installer.

A recent domestic Solar Thermal installation (click on an image to enlarge):

Solar Thermal 1 Solar Thermal 2 Solar Thermal 3

What are the pricess and maintenance costs?

Prices for PV systems vary, depending on the size of the system to be installed, type of PV cell used and the building on which the PV is mounted.

For the average domestic system, costs can be around £4,000-£6,000 per kWp installed with most domestic systems usually between 1.5 and 2 kWp. Solar tiles cost more than conventional panels and panels that are integrated into a roof are more expensive than those that sit on top. If you intend to have major roof repairs carried out it may be worth exploring PV tiles as they can offset the cost of roof tiles.

Systems connected to the national grid require very little maintenance, generally limited to ensuring that the panels are kept relatively clean and that shade from trees has not become a problem. The wiring and components of the system should however be checked occasionally by a qualified technician. For stand-alone systems, i.e. those not connected to the national grid, further maintenance is required on other system components, such as batteries.

What are the benefits of solar energy

  1. No C02 emmisions
  2. Save money on energy bills
  3. Not dependent on fossil or nucleur fuels