Solar Panels

Photovoltaics?

Solar photovoltaic panels are panels that convert the suns energy into electrical energy. They differ from some panels which use the suns energy to heat up water in tubes which can be used for heating and showers for example. Panels are passive devices in that there are no moving parts and once installed photovoltaics are fairly maintenance free with little care required to efficient operation.

How do photovoltaics work?

Solar panels work wherever there is sunlight. They convert sunlight energy direct into electrical power without any conversion via another medium – making them effective and great for energy generation purposes. They can work in quite low level light conditions – consider a solar powered calculator – they work pretty much most of the time even in low light level conditions such as a dimly lit room. There is no threshold minimum intensity – such as that of other types of energy generation such as wind, and this makes them an ideal generation mechanism.

What are photovoltaics made of?

Semiconductors such as silicon are primarily used. Thin film solar has approximately 15% of the market the other 85% is crystalline silicon.

Here’s the technical bit…

An incident photon (a light particle) hitting the solar panel photovoltaics can excite electrons in the medium into another state called an exciton – which is effectively a positive charge and a negative charge. The structure of photovoltaic then helps to split these charges apart and thus a voltage can be generated. The voltage can then be used to drive current and do something useful such as power a laptop.

The power can be stored directly into a battery, used or fed back into the grid and this last option may lead to you getting a cheque from the power company. When you are not using your power or storing – it can make economic sense to sell it. More about feed in tariffs and how to make money by selling power is discussed later.

What’s the efficiency of PV or Photovoltaics?

Typical efficiencies are of the order of around 20%. Efficiencies are rising all the time and differing materials and manufacturing techniques can yield higher and lower efficiencies. The efficiency of a PV cell is measured in kilowatt peak (kWp) – energy generated by the Photovoltaic cell in full sunlight.

What do I need to start generating power?

You need a photovoltaics array, suitably aligned to capture as much of the suns rays as possible (pref south facing) and not overshadowed by buildings or trees. You need an inverter such that you actually use the power which converts the DC (direct current) generated from the PV cells into AC (alternating current) such that it can be used by household systems or fed into the grid.

How much do photovoltaic systems cost?

This depends on the size of the installation. It could cost a few thousands and the actual amount depends on rebates – PV type used, installation costs and such like.

How do I buy?

For a householder you can contact any number of reputable installers and providers who will happily give you a quote for the work and tell you how much money you can expect to save as a result of the installation.

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