What is a solar photovoltaic system?

A solar photovoltaic system generates electricity from sunlight. The main components of a solarphotovoltaic system are: 

1. Solar photovoltaic modules

• Converts sunlight to electricity
• 16% – 19% efficient
• Fix to pitched or flat roofs
• 1m2 generates roughly 100 kWh’s / year
• Very low maintenance – no moving parts
• Useful lifetime – 20 to 25 years

2. Inverter

• Converts DC (direct current) electricity produced by solar photovoltaic panels into 230V50Hz AC (alternating current) electricity used in domestic appliances
• Used in Stand Alone (off-grid battery systems) and grid-connected systems
• Comes as part of system package

3. Production meter

• Records units of electricity (kWh’s) generated by solar PV modules
• Comes as part of system package
• Homeowners responsibility
• Separate from Import-export meter - This records units of electricity imported from and exported to the national electricity grid. Most homeowners do not have this facility and it is the responsibility of utilities, not homeowners.

4. Electricity grid

• Acts as giant energy storage system, eliminating the need for battery storage
• Enables export of surplus electricity generated by the PV system
• Enables electricity power to be imported when demand exceeds supply
• Enables micro-generators to sell power to utilities through Feed-in-Tariff
• Grid connection reduces system costs and management

Is there enough sunlight in the UK for a solar photovoltaic system to work?

There is plenty of sunshine available in the UK for generating electriicty. The map below showsaverage total solar irradiation (kWh/m2) at 30 degree incline facing due south. However, there isconsiderable seasonal variation of the order 5:1 between summer and winter sunlight availability,with implications for the amount of useful energy captured by the solar panels at different time ofthe year. The graph shows the typical split between direct (beam) sunlight and diffuse (scattered)sunlight experienced in the UK.

Is your house suitable?

Solar photovoltaic systems are now a permitted development right, unless your home is located in a dedicated conservation area (not to be confused with AONB) or is a listed building – in the latter case planning permission will be always be required.  Ideally the roof of your home should face in a southerly direction, preferably between southeast and southwest (135 degrees and 225 degrees), although anywhere between east (90 degrees) and west (270 degrees), through south, will suffice.  Solar photovoltaic panels can be mounted on either a flat or pitched roof, yet consideration must be given shading risks from nearby trees, buildings or steep hillsides.    

How does a solar photovoltaic system work?

Solar photovoltaic panels are located in a position that optimises the capture of solar radiation -usually the roof, but they could also be pole mounted in close proximity to the dwelling.  DC (direct current) electricity flows from the PV panels to a device called an inverter – this converts the current to AC (alternating current) for use in typical domestic appliances and for feeding into the national electricity grid.  In most systems that are “grid-tied” or “grid-connected”, electricity produced from the photovoltaic panels is first consumed within the building, with any excess electricity exported to the grid.  Conversely, at times when demand from household appliances exceeds output from the photovoltaic system, power is drawn from the grid as required.  From the point of view of the user, the transition from grid to PV system is seamless (no flickering or outages), and requires no input from the user.

What can you expect from a solar photovoltaic system?

The amount of electricity generated by a solar PV system is dependent upon its size (watt-peak output – usually expressed in kilowatts or kWp).  Typical UK household systems range in size from 1 to 6kWp, with the main constraints being available roof area and budget.  As a rule of thumb, a 1kWp system will require roughly 7m² of solar panels and will typically produce 800 kWh’s per year, with precise output depending upon the orientation and angle of the solar modules, which if roof mounted, will be dictated by the dwelling orientation and angle of the roof.  Through extrapolation, a 2kWp system will require 16m² and generate 1,600 kWh per year and so on.  Instantaneous and daily output will very due to weather conditions (sunny days are best) and due to seasonal variations in the strength of the sun (note - the strength of the mid summer sun is five times stronger than in mid-winter).

What is meant by “tilt and orientation” and how this affects output from solar panels?

This refers to the position of the solar collectors relative to the sun, and how this impacts on the amount of energy captured by the panels.  Ideally, solar panels should be positioned (oriented) to face due south and placed an angle (tilt) of between 20 – 50 degrees.  The graph below shows the effect of tilt and orientation upon energy generating potential.  The ideal positioning for solar photovoltaic panels is to face due south at an angle equivalent to the latitude of the location minus 20 degrees (see, for example, the chart below for London at 51 degrees N with an optimum angle of 31 degrees, identified by the black dot in the bright yellow segment).  As orientation shifts away from south (towards east or west, or worse, north), and / or the angle of the solar panel moves out of the 20 to 50 degree range, output decreases.

What might it cost?

The approximate cost of installing a grid connected solar photovoltaic system is set out in the table.  For a proper quotation, please call the office on 01452 772030 or email: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it

How is the government helping?

There is currently no grant available for solar photovoltaic system, following the closure of the Low Carbon Buildings Programme.  However, the grant system has been replaced by the clean energy cash back scheme or feed-in-tariff, which rewards producers of renewable electricity.

More about feed-in-tariffs

A feed in tariff (FiT) is a policy tool that can be used to set above-market rates for electricity generated from renewable sources. The feed in tariff obliges electricity utility companies to buy renewable electricity at a fixed price for a fixed number of years – in the UK, the time period will be for 25 years.  The feed-in-tariff considerably improves the cost effectiveness of installing solar photovoltaics for the consumer.

By offering above market prices for electricity generated, for example, paying renewable generators 21p per kWh unit instead of the current retail electricity price (approximately 12 p/kWh), utility companies and consumers will see that there is money to be made by installing PV solar panels and wind turbines, etc.  Feed in tariffs used in other European countries and elsewhere around the world have been shown to considerably improve the uptake of microgeneration technologies.

The feed-in-tariff provides financial benefits in 3 ways:

• A fixed payment from the electricity supplier for every kilowatt hour (kWh) generated (the generation tariff)

• Another payment additional to the generation tariff for every kWh exported to the wider energy market (the export tariff).  Generators will be guaranteed a market for their exports at a long-term guaranteed price.  The generator may chose whether to sell exported electricity to the supplier at this guaranteed export tariff, or negotiate a price for exported electricity in the open market.

• In addition, generators will benefit because they will have the opportunity to use that electricity on-site to offset some or all of the electricity they would otherwise have had to buy.

Are there any planning issues?

One of the conditions of the grant scheme is that you have received planning consent from your local council - please note, this is different from planning permission. For the majority of home owners the addition of solar PV panels fall within 'permitted development rights', which means that the panels will be more or less flush with the roof. If your property is in a conservation area, Area of Outstanding Natural Beauty or is a listed building you may need to apply for full planning permission. We recommend checking with your local council to see what their stance is on solar PV panels, although most people install PVs without doing this.