What is PV?

The photovoltaic (PV) process converts sunlight, the most abundant energy source on the planet directly into electricity. The equipment required for this process has no moving parts and as a result requires minimal maintenance. In addition, the electricity is generated with no emissions and no noise. A PV cell consists of two or more thin layers of semiconducting material, most commonly silicon. When the cell is exposed to light, electrical charges are generated and this can be conducted away by metal contacts as direct current (DC). The electrical output from a single cell is small, therefore multiple cells are connected together to provide a more useful output. Cells connected in this way are encapsulated (usually behind glass) to form a weatherproof module or panel. Multiple modules can likewise be connected together in order to provide sufficient power for common electrical appliances.

 

How long has Solar PV technology been around?

In 1838 the photoelectric effect was discovered by physicist Edmund Becquerel although it wasn't until the 1950's that the technology was developed enough to produce efficient working cells. During the 50's and 60's Solar PV was put on satellites and sent into orbit but it was still too expensive for general use. The next few decades brought better technology with lower prices and Solar PV was installed in world-wide remote villages to provide electricity for where there was no supply. Grid-connected Solar PV has had a massive growth since 1990's in the more developed countries of the world.

 

Are photovoltaic panels expensive?

Over the last 20 years the price of PV modules have fallen dramatically, from around £15 per Wp in 1980 to current prices of around £3.50 per Wp. That means that a single module, typically generating 60W of power under standard test conditions, now costs around £200 Solar PV is still a more expensive technology than most other forms of renewable energy, but it has many advantages over other systems.

 

Doesn't PV technology need bright sunshine to work properly?

The electrical output of a PV cell is dependent upon the intensity of the light to which it is exposed. So PV cells will tend to generate more electricity on bright days than when skies are overcast. However, photovoltaics do not need to be in direct sunlight to work, so even on overcast days a PV cell will be generating some electricity.

 

Is PV suitable for use in the UK?

In the UK, we get 60% of the sunlight received at the equator - so there is still a lot of potential energy available! PV has been used in the UK over the last 20 years or more for many applications, particularly in remote areas where grid connection is impractical, such as weather monitoring stations, marine navigation aids, etc. Over the last few years PV technology has also started to be introduced into urban areas, incorporated into the roofs and facades of homes, offices and factories. A modest sized domestic grid connect system will provide a substantial portion of a households electricity needs for over 6 months of the year and installations on commercial buildings are particularly suitable, meeting the daytime demands of an office. Over 1.5 MW of building integrated PV is already installed in the UK.

 

What applications are there for PV?

PV technology has many applications in the UK, both for stand-alone systems and for integration onto buildings. PV has been used for many years in the UK in applications such as monitoring stations, radio repeater stations, telephone kiosks and street lighting to name just a few examples. There is also a substantial market for PV technology in the leisure industry, with battery chargers for boats and caravans, as well as for powering garden equipment such as solar fountains. In more recent years in the UK, PV has become more widely used in urban areas, where it can be integrated into new buildings or mounted onto existing buildings. This is a rapidly growing market in the UK and throughout Europe. PV technology is ideally suited to the urban environment, providing pollution and noise free electricity without using extra space. PV technology is also widely used in the developing world. The technology is particularly suited here, where electricity grids are unreliable or non-existent, with remote locations often making PV power supply the most economic option. In addition, many developing countries have a high level of solar radiation levels year round.

 

How long will a system last?

The average lifetime of a PV module can be in excess of 20 years, crystalline silicon modules in particular have a very long life span. In addition, they require very little maintenance. In fact, even after 20years, the PV modules will still be producing power, but the output will reduce by 10-20%

How much will I need to power my home?

A typical domestic PV system of 2.1 kWp in the UK would produce around 50-60% of the annual demand of an average family household (taking the average demand to be around 10 kWh per day). However, due to the Feed In Tariff incentive, a 1kW PV system will produce enough revenue to give you a net zero electricity bill! Of course, if you put in a bigger system, you will make a healthy profit! See our FIT FAQ for more information.

 

What is the efficiency of the Solar panels?

There are different types of solar panel technology and the size of available roof space, angle to the sun, pitch of the roof and budget will have an effect of how much solar electricity you can produce. Below is an overview of the different solar panel technology.