Solar power is radiant energy emitted by the sun. In order to reduce our consumption of conventional fuels and minimise our carbon footprint, we can harness this energy and rely on it as a power source. This is mainly achieved through Photovoltaics (solar PV) and solar thermal heating. Solar PV converts the sun’s radiation into electricity to help meet the increasing demand for power whereas solar thermal heating integrates a collector and boiler system to heat water and can be used for space heating, hot water and swimming pools.
‘Photovoltaic’ is a combination of two words; ‘photo’, Greek for light, and ‘voltaic’, from ‘volt’, meaning electrical power.The solar cell is the main component of Photovoltaic technology and Solar PV systems use these cells to convert solar radiation into electricity. These solar cells consist of one or two layers of a semi-conductor and the most common material used in these cells is silicon, an abundant element most commonly found in sand. Solar cells can be wired together to form a module (a solar panel) and these can then be connected together to form an array.
When light shines on the cell it creates an electric field across the layers causing electricity to flow. The more intense the light is, the greater the flow of electricity. However, PV cells produce electricity in the form of direct current therefore an inverter is required to convert this electricity to Alternating Current which can then be used in your house and exported to the national grid.
There are 3 basic construction types of Photovoltaic solar panels:
Crystalline – Monocrystalline
Monocrystalline cells are cut from a single crystal of silicon and are the most efficient type of cell, but also the most expensive to produce. They are completely rigid and must be mounted in a rigid frame for protection.
Polycrystalline cells are made from a slice cut from a block of silicon that consists of many crystals. Solar PV panels made from these types of cell are slightly less efficient but cheaper than monocrystalline cells. They also need to be mounted in a rigid frame.
Thin Film – Amorphous
Amorphous cells are manufactured by placing a thin film of non crystalline silicon onto a wide range of surfaces. This creates the least efficient type of PV panels but also the cheapest and if manufactured on a flexible surface, the whole PV panel can be flexible. One problem with amorphous cells, however, is that their power output reduces over time, particularly during the first few months, after which they become stable.
Lower carbon emissions
Solar PV electricity is renewable once the installation offsets the carbon emitted during its construction. A typical 2.5 kWp system could provide up to 50% of a household’s annual electricity, saving around 1200 kg of CO2 per year and around 30 tonnes over its lifetime.
Lower energy bills
Solar is capable of producing up to 50% of the annual electricity consumed in a typical house, electricity bills could be reduced significantly which would provide protection against rising energy bills.
Energy storage options
If a home is not connected to the national grid, Solar PV systems can provide alternative energy that may be far more flexible as excess electricity can be stored in special batteries.
PV systems are typically rated in kWp (kilowatt peak) which indicates the combined potential capacity of all the PV modules installed under prime conditions.Roughly speaking, if a solar PV system faces due south and is installed at an angle of 30⁰ and is unshaded, each installed kWp can be expected to produce around 850kWh (units) of electricity per year in the UK. A 2kWp system would thus produce approximately 1,700kWh / year, around half of the annual electricity consumption per average household.