Solar power is produced by conversion of energy from sunlight into electricity, most commonly using photovoltaics (PV) panels.
Photovoltaic panels use silicon to convert solar energy into electric. The PV solar cells act as a semiconductor which absorb sunlight and transfer the energy to negatively charged particles (electrons) that flow through the semiconductor as electrical current.
Photovoltaics (PV), or Solar Electric, work by converting the sun's energy into electricity using roof-mounted (most common solution for dwellings) panels. Cheaper units convert just 5 per cent of solar energy into electricity and more efficient, and more expensive units, convert up to 18 per cent of energy received into electricity - panels are continuously developing and improving.
Power output depends on the type of materials used in construction and the amount of sunlight received. The maximum output from PV systems is in the summer, but the maximum power usage in a property is in mid-winter. Energy from these systems can be sold back to the National Grid – note the feed-in tariff (FIT) scheme closed to new applicants from 1 April 2019.
A maximum output energy rating for panels can be misleading and does not relate to the amount of resource (sunlight) that is actually available at any one location. A better way of comparing panels is their % efficiency; this tells you what % of the light landing on them they will turn into electricity. This combined with a figure for the average solar radiation at your site and the size of the panels will give you a far better idea of how much electricity you will generate.
The following are rule of thumb approximations for photovoltaic (PV) panel installations which can be used for preliminary scheme selection.
An installation with an orientation of south 0° and inclination of 35-45° will provide the maximum yield from PV panels.
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The three most common silicon cell types in current use are: monocrystalline; polycrystalline and thin film amorphous silicon.
Monocrystalline (single cell) solar panels are made using cells saw-cut from a single cylindrical crystal of silicon, this is the most efficient of the photovoltaic (PV) technologies. Monocrystalline panels have high efficiencies, typically around 15-20%, although the manufacturing process required to produce mono-crystalline silicon is complicated, resulting in slightly higher costs than other technologies.
Polycrystalline (multi-crystalline) panels are made from cells cut from an ingot of melted and recrystallised silicon. In the manufacturing process, molten silicon is cast into ingots of polycrystalline silicon; these ingots are then saw-cut into very thin wafers and assembled into complete cells. Polycrystalline cells are cheaper to produce than monocrystalline ones. Efficiency of polycrystalline solar panels is only around 12-16%.
Amorphous silicon (thin film) cells are composed of silicon atoms in a thin homogenous layer rather than a crystal structure. Amorphous silicon absorbs light more effectively than crystalline silicon, so the cells can be thinner. Typical efficiency of around thin film solar panels is 6%, but they are easier and therefore cheaper to produce.
1 m2 of monocrystalline or polycrystalline array will provide a useful output of 90–110 kW·h per year, whereas 1 m2 of amorphous thin film array will provide only 30–70 kW·h per year.
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Solar Electric id: lzc-03