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You'll probably have heard a lot about photovoltaic (PV) technology, since the Government's Feed-in Tariff (FiT) scheme has been very popular. This offers guaranteed payments for every kWh of electricity generated using PV panels and then either used or fed back to the Grid.
While the FiT rates are now significantly below the original rates when they were introduced in 2011, these can still be attractive for those considered including photovoltaics within any new build or refurbishment projects. The significant fall in manufacturing costs means that the FiT rates can still normally provide a 10 year payback, even at the lower current FiT rates.
But Feed-in Tariff income aside, what is the case for photovoltaics, and what are the considerations that should be borne in mind?
Firstly, we'll look at the benefits:
- Photovoltaic panels are a standalone technology that can be 'bolted on' to a scheme – there's usually no need to make any significant changes to a building's design or specification.
- Because of the placement of the photovoltaic panels, PV is a very visible measure which can provide a good 'green advert' for the site in question. Everybody will know that this is an eco-friendly development.
- Since any excess electricity generated can be exported to the Grid, there are no limits on system size – your photovoltaic array is only limited by the size of suitable roof area.There is however one limitation that should be taken into account:
- If you're planning a photovoltaic installation, roof design needs to be carefully considered. This is because the efficiency of PV panels is reduced (and therefore payback period is increased) if they are angled higher/lower than 30°, and/or orientated at any aspect other than due south. In addition, there are some other considerations that should be borne in mind:
- Photovoltaic panel output reduces with age. Manufacturers provide guaranteed maximum percentage reduction in output over a 20-25 year period, so it is worthcomparing these before deciding on a particular product.
- PV panels are installed in series, called strings. Any shading on one panel will affect the output of the whole string, therefore the layout of a photovoltaic array needs to be considered carefully.
- Inverters – which are necessary to convert the DC current from the photovoltaic panel to the AC required by our electrical systems – can make a high pitched humming noise when they run. This can be picked up by people with sensitive hearing, which means that the location of the inverter should be considered carefully.If you'd like to find out more about photovoltaic panels, and their suitability for a particular project, please contact us. You might also want to consider another type of renewable electricity generation, the wind turbine.