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Solar PV

Solar photovoltaic (PV) panels generate electricity from daylight, although they produce most in direct sunlight. The south East receives the highest levels of solar radiation in Ireland, and so is well suited to solar PV panels.

Are there any local businesses or home owners or community organisations who would like to install pv on their roof spaces?

Solar Resource

The south east of Ireland has the best solar resource in Ireland, with average horizontal irradiation levels of over 1000 kWh/m2.

The Technology

Solar PV can be supplied as panels or tiles and can be built into the fabric of a building, bolted on afterwards or built on a frame on the ground. There are three main types of PV panel:

  • mono-crystalline, which are the most expensive and the most efficient
  • polycrystalline, which are medium cost and efficiency, and
  • amorphous or thin film. These are the cheapest and the least efficient, but are light weight flexible sheets that can be bonded onto other materials.

An inverter is needed to convert the direct current (DC) electricity output of the PV panels to alternating current (AC) for immediate use, export to the grid or to charge batteries.

Scale

In general, solar PV needs 7 to 8m2 per kW of installed capacity. Typical system sizes for domestic panels range from 1 to 4 kW so 7 to 32m2. Commercial arrays have the potential to be much larger and are limited only by roof space available.

Solar PV in the south west is estimated to have a capacity factor of around 0.1.

A 2.2 kW domestic polycrystalline PV system will produce an average of around 1900kWh of energy per year, equivalent to around 40 per cent of the average domestic electricity consumption. A system of this size would be approximately 5.5 m x 3.6 m.

A 50 kW array will produce an average of around 43,800 kWh of energy per year, equivalent to the average electricity consumption of 9.3 homes. A roof mounted array of this size would need approximately 400 square meters.

Operation and Maintenance

PV panels have very low regular maintenance requirements; a visual check for debris by the owner on an annual basis is usually sufficient.

Commercial Considerations

Solar PV is a relatively well developed technology and prices have been falling over recent years across the world as the market matures. A Feed-in Tariff is required which would offer a guaranteed income for 25 years for solar PV projects.

There may be opportunities to bulk buy solar panels or to set up a solar buying club to reduce costs for community projects intending to install panels on multiple roofs. In some countries there are also “PV for free” schemes that mean developers will install panels on a roof for free, they will claim the Feed-in Tariff and the householder or building operator will receive discounted or free electricity. Details of these offers should be investigated carefully, as there are big differences between the different options available.

For more information

Watch a PlanLocal video on ‘Solar power: an introduction’.