Photovoltaic Cells are more commonly referred to simply as Pv's. Pv's are another form of solar collector, instead of harvesting the suns energy and turning it into heat energy like the solar thermal panels, Pv's convert the energy into usable electricity.
A typical Pv cell has a surface area in the region of 1.5 mtr sq and an output ranging from 125 watts to 220 watts depending upon the make and model of the particular Pv cell. On there own one Pv does nothing worthwhile, however when they are grouped together the collective power can be considerable, there is no limit to the number of Pv cells than can be grouped into a solar array.
Typical domestic Pv arrays are usually no less than 2.3KWp (2300 watts) @ peak output. To obtain this output 15 x 150 Pv cells would be linked together taking up an area of about 23 sq metres. On new build homes this area is usually made available by utilising the south facing pitched roof.
A Pv cell looks very different to a solar water heating cell and is much more sophisticated and manufactured in laboratory type conditions. They have the appearance of a sheet of very dark glass with a hatched silver colour grid inlaid into them, they are quite light at 17 kg each, and often weigh less than the tiles they replace, so when mounted cause no structural impact upon the roof. Larger and typically commercial installations require the Pv's to be mounted onto proprietary "A Frames" at ground level or on-top off office buildings.
Until fairly recently it was not practically possible to install PV cells into the domestic /commercial properties because the power providers would not except the "spillage" this is unused electricity generated by the Pv array, back into the grid. Happily, today this has changed and the power providers will buy back any surplus spillage electricity and allow it into the national grid.
The electricity produced can be used to power virtually anything, fridges, freezers, televisions, washing machine, water heater immersion elements and all manner of things. A well designed Pv installation should dramatically reduce the electrical consumption of the home and during daytime provide sufficient power to cover the base load requirements of the dwelling completely.
The Components of an Installation
A modern efficient Pv system has three main components, solar Pv cell, an inverter, and a device that manages the energy generated.
Solar Pv Cells.
Photovoltaic cells are packaged together into convenient modules to produce specific voltage and currant during daylight hours. These packages typically have outputs of 2.3KWp, 3.5KWp, 4.6KWp, 6.1KWp and 8.0KWp for the domestic market. Commercially virtually any size output can be attained, however design and installation are extremely complex and sophisticated.
All solar Pv cells generate DC electricity. This must be converted into AC electricity before it can be used within the home and conveyed around the household electrical circuits. A device call a grid connected (or grid tied) inverter is used to do this. Grid tied inverters are manufactured by specialist companies and have to undergo rigorous testing before they are allowed into the market as safety is of paramount concern.
The energy manager is another essential piece of the jigsaw, its job is to ensure that the solar Pv system is as economical and efficient as possible and to prevent any surplus power generated by the solar Pv system being lost to the grid during periods when energy production is greater than energy demand (such as on a bright sunny day when everybody is out and demand is low). This device, called EMMA (energy and micro-generation manager),
Solar Pv systems have no moving parts, are modular (so they can be sized to match power requirements on any scale) they are reliable, and easily installed. Pv cells are a life long product, most top quality manufacturers guarantee the performance output for at least the first 20-25 years of operation, and generally they predict an operational life well in excess of 30+ years.
Not all European countries, as is the case here, within the Channel Islands, have adopted the Building Energy Ratings System, this is an officially regulated method of calculating the energy efficiency of your home, however, in areas where BER exists, Pvs can make a very significant improvement upon the buildings BRE rating.
Unlike solar thermal systems, 100% of the output from the solar Pv systems can be used to displace electricity purchased off the grid and to thereby generating enhanced energy credit ratings. This energy rating credit, (which in parts of the United Kingdom and Ireland is 2.7 times the output from the Pv system) is subtracted from primary electric consumption figures when calculating a building energy rating. As a result of this, even a modest Pv installation will have a significant positive effect on your buildings BER.
Another positive benefit, is the requirement for all new buildings to meet higher energy efficiency levels, to comply with Building Regulations. In countries such as Ireland these regulations require that a minimum of 10 KWhr/msq/year of thermal energy or 4 KWhr/m2/year of electrical energy must come from renewable sources. This requirement can be very easily and economically met by a modest Pv installation.
DIY pre-packed kits containing all the required materials including the controller and installation instructions are available from us via our web site DIY purchasing section (due for launch November 2008) for approximately £4,800.00 per KWp, plus gst and/or vat as aplicable and delivery.
Installation of these Pv systems is relatively straight forward and can be undertaken by any reasonably competent DIY enthusiast, however we advise that a professional qualified electrician be engaged to make the final connections to the fuse board. As described previously the Pv collectors can be mounted onto the south facing part of the roof or at low level on property "A Frames". The Pv modules are then linked by a pair of plug and play DC cables back to the inverter, and then onto the main fuse-board, this final section of work is best undertaken by a qualified electrician.
If you would like a site any further information or a site survey, please email us your details for rates in your area.