The difference between Photo Voltaic and Solar Heating Systems
The differences between photo voltaic and solar heating systems explored. The two main solar panel systems available are photo voltaic panels and solar heating. This article aims to provide you with some background information on both systems, allowing you to make an informed decision on which solar panel system is right for you.
Photo Voltaic Panels
The difference between photo volatic and solar heating is that where solar heating is used to heat water, photo voltaic systems generate electricity. Solar panels - or photo voltaic panels - contain a number of modules connected in series which react to light energy, generating electricity through the photo voltaic effect. This electricity is used to power your home meaning you will draw less power from your electricity provider, in turn, saving you money. The electricity is monitored by a Total Generation Tariff Meter which records how much electricity is generated, some of which is fed into the power grid, which your electricity provider will pay you for. The electricity generated by the solar panel array is sent through an inverter which converts the electricity from DC (Direct Current as found in batteries) to AC (Alternating Current as found in your home's electric circuits).The electricity generated can be used straight away as well as automatically being sent to the power grid.
Currently, the rate at which you get paid is 43.3 pence per kilowatt hour; this is called the Feed In Tariff. However, it has recently been announced by the Government that the Feed In Tariff will be reduced to a proposed rate of 21p/kWh - it should be noted that this is still under consultation and has not yet been finalised.
Alongside photo voltaic panels, solar tiles are also available. These have been specifically designed to replace conventional roofing tiles, and are normally used either when replacing a roof or when regular solar panel installations are not available for aesthetic or planning reasons. Solar tiles cost somewhere in the region of twice that of a regular panel system, although the savings from not purchasing normal roof tiles or slates would need to be factored into any calculations.
Solar Heating
Solar heating comes in two forms, solar tubes and solar flat plates. Both solar tube and solar plate systems rely on harnessing the warmth from the sun's radiation to pre-heat water for your hot water as well as for radiators and under floor heating, meaning you will consume less fuel to heat the water in your system. The solar heating panels are generally fixed to the roof of your house - although they can also be installed at ground level in a garden for example. Water is passed through the tubes or plates, where it will be heated before being pumped into a hot water cylinder or boiler to be stored and used whenever it is required.
As a rule of thumb, a solar heating array will provide all of your hot water in the summer and around a third of your requirements throughout the whole year.
Direct and Indirect Solar Heating Systems
As the name suggests, direct solar heating systems circulate the water which will be used in order to heat it. Whilst these systems are cheaper to install and are more efficient at heating the water, the trade-off is that they often offer no freezing or over-heating protection and in hard water locations the collection tanks can accumulate scale.
Indirect solar heating systems make use of a heat exchanger and a "heat-transfer fluid" which circulates through the collection tank in which the water to be heated is stored. This method is less efficient and is more costly to install, however, they do offer freeze protection and over-heating protection.
Active and Passive Solar Water Heaters
Solar water heating systems are either active or passive. In an active solar water heating system, the water or heater transfer liquid is circulated around the system with the use of an electric pump, a passive system utilises convection to circulate the water.
Although more expensive, active solar water heating systems are generally accepted as the best choice for most situations as they offer a number of benefits over passive solar water heating systems including greater efficiency and the ability to locate the storage tank lower than the solar panels as well as hiding storage tank from view.
