Solar PV

Frequently Asked Questions

1.0 About Solar PV Technology

Solar is an energy source, and the panels we supply absorb natural light rays from the sun in order to generate electricity. This is a truly renewable energy source, powered by the sun, meaning there is no end to the supply. Having solar power in Ireland is beneficial for homeowners, business owners and especially the environment. Solar power is both cost-effective and a low-cost alternative supply of electricity, with it also being much more beneficial for the environment than electricity from coal and other energy sources. Below are responses to some of our most frequently asked questions relating to solar electricity generation:

1.1. What are solar panels? 

Solar panels which produce electricity are referred to in the industry as ‘solar photovoltaic (PV) modules.’ These are panels made from materials which generate DC electricity when exposed to light. Waterpower supplies solar PV panels for domestic and commercial premises.

1.2 How do Solar PV panels work?

The photovoltaic effect only takes place in a reduced number of materials, called semiconductors (such as silicon -monocrystalline, polycrystalline and amorphous- and cadmium telluride), that, after specific chemical procedures , allow the generation of an electric current when exposed to light. Those semiconductors are shaped into thin layers that conform the core element of solar cells, the basic element of a solar PV system, that produce a direct current.

A typical panel size is 1 square meter and produces one fifth of a kW (200 W) when the sun is shining. The panels are then interconnected to generate larger amounts of electricity; this is called a PV system. A domestic installation of 5 or 6 kW is typically mounted on the South facing roof of a house, while 15 or 20 kW could be mounted on the South facing roof of a barn to supply much of the energy needs of a farm. This demonstrates one of the great advantages of solar electricity; it is modular, allowing any size PV system to be built to fit the available space or budget.

1.3. What is the difference between Solar PV and Solar Thermal 

There are two forms of solar power technology – Solar PV and Solar Thermal. The core difference between solar photovoltaic (PV) and solar thermal can be found in their working principles. Solar PV is based on the photovoltaic effect, by which a photon (the basic unit of light) impacting a surface made of a special material generates the release of an electron. Solar thermal, on the other hand, uses sunlight to heat a fluid (depending on the particular application, it can be water or other fluid). Waterpower only supplies ‘Solar PV’ panels for our customer base.

1.4. What different types of Solar PV panels exist?

Waterpower offers two types of Solar PV panels a) Monocrystalline and b) Polycrystalline. These vary in size and output. Our engineers will design the optimal solar pv system for your site to ensure you receive maximum value for money. 

1.5. Do solar panels work in Ireland?

The amount of electricity produced by a solar system each year is known as the solar yield and depends mainly on local meteorological conditions. Solar panels work in sunny, cold and even cloudy environments. The highest solar yield in Ireland, achieved in the near coastal regions between Mizen Head and Wexford, is 1000 kW Hours/installed kW/year. This is the same yield as is achieved near Munich in southern Germany as well as on the South coast of England, both locations having hundreds of thousands of solar PV systems installed. The SEAI published an interesting report on the value of Solar PV in Ireland which is available from here

1.6 What are the advantages and disadvantages of Solar PV?

Solar PV systems are more versatile than Solar Thermal as they don’t just heat up water they can power many appliances. Since it is modular it is ideal for use for small scale (eg farm or domestic) applications where each owner becomes an electricity producer, using whatever electricity is needed at the time, selling the surplus to the grid and purchasing from the grid when no renewable energy is available.

For small scale renewable energy generation (less than 50 kW) a PV system is a more attractive option then a wind turbine as it has little or no visual impact and, having no moving parts, produces its electricity silently. It is also virtually maintenance free over its lifetime of 20-25 years making the cost of solar electricity competitive with that produced by noisy, unreliable and visually intrusive wind turbines. Also, wind turbines produce one third of their electricity at night when demand is at a minimum whereas solar produces all of its electricity during the daytime when the demand is maximum. Please visit our solar pv page for more information on the benefits of Solar PV.

2.0 Installations

2.1. Do I need planning permission to install solar PV on my roof? 

Larger solar PV systems on domestic rooftops will typically require planning permission. Solar PV systems installed in a domestic setting under 12 sq. m (and representing less than 50% of the total roof area) are exempt from planning. Visit the page on conditional planning exemptions for the full details.

2.2. What will be installed in my home if I purchase a rooftop solar PV system?

The main components are the solar panels which will be located on the roof area, and the inverter which will be located within your house or attic. The solar panels convert the light into DC electricity, and the inverter converts this DC electricity into AC electricity for use in your home. The solar system will be connected to your main electricity panel (‘fuseboard’).

2.3. How will the solar panels be fixed to my roof?

There are a number of well-proven solutions to connect the solar panels to your roof. Most solutions fix the solar panels above the existing roof tiles on aluminium rails, but some solutions allow for an integrated, ‘flush’, connection where the roof tiles are removed and replaced with the solar panels.

2.4. How can I maximise the amount of electricity generated that I use?

The simplest way to use a higher percentage of the electricity generated is to design the PV system to meet the electricity demand of the house, although this may mean a very small PV system is installed if demand is low during the daytime.

Another simple measure is to install a ‘diverter switch’ which diverts any unused electricity to heat your hot water in your immersion tank. In this way some of the energy generated is stored as hot water, which you can use later.

2.5. Are solar panels right for my business or building?

There are a variety of considerations when determining whether or not solar panels are right for your building. Some thought must go into how much of the generated electricity you will use as this will affect how economic it is as a solution for you.

You also need to consider if the roof is suitable for solar PV considering the age and condition, the orientation, and any potential shading from nearby trees or buildings. The best rooftops for maximising electricity generation are those that are south-facing, in good condition and with minimal shading from trees or adjacent structures.

3.0 Grants & Supports

3.1. What supports are there for solar PV in homes? 

  • Home Renovation Incentive: Most home solar PV systems will be eligible for an income tax credit under the Home Renovation Incentive. Homeowners can avail of a 13.5% tax credit on qualifying expenditure over €4,405 (before VAT) per property.
  • Grants: Grants are not currently offered for individual solar PV systems. Some community solar PV systems have been supported through the Better Energy Communities programme as part of a wider suite of measures.
  • Building Regulations: Part L of the domestic building regulations requires a minimum share of the energy consumption of new homes to be provided by renewable sources. Solar PV systems can meet this obligation and thus their uptake is driven in part by these building regulations. Installation of these systems also improves the overall Building Energy Rating (BER) of the property

3.2. What supports are there for solar PV in businesses and other buildings?

  • Accelerated Capital Allowances: The ACA is a tax incentive aimed at companies paying corporation tax, sole-traders and non-corporates. The scheme allows them to write off 100% of the purchase value of qualifying energy efficient equipment against their profit in the first year of purpose. Solar PV systems can qualify for the scheme provided the model of solar panel is registered on the Triple E Register.
  • Grants: Grants are not currently offered for individual solar PV systems. Some commercial rooftop solar PV systems have been supported through the Better Energy Communities programme as part of a wider suite of measures.

3.3. Is there a ‘feed-in tariff’ payment for excess solar electricity fed into the grid by owners of solar PV systems? 

There is currently no obligation for energy suppliers to pay their customers for the electricity they generate with their solar panels (sometimes known as a ‘Feed-in-tariff’).Waterpower will however  buy excess power from our commercial customers subject to terms and conditions

4.0 Solar farms

4.1. What is a solar farm?

A solar farm is a large array of solar panels, installed in fields or other large spaces, feeding all of the generated power to the electricity grid. Sometimes these are referred to as a solar park or a ground mounted solar array. In a solar farm the solar panels are installed on mounting systems approximately 3m high which are piled into the ground like fence-posts. Rows of these mounting systems would be a typical feature of a solar farm.

4.2. How much land is required for a solar farm?

Solar farms can be any range of sizes, but around 4-5 acres (1.6-2 hectares) is required for each Megawatt (MW) of solar panels installed (around 4,000 panels per MW).

4.3. What information is available on planning for large-scale solar farms in Ireland?

There are currently no large-scale solar farms in Ireland but there are a significant number in the UK. Information on planning requirements and the appropriate siting of solar farms in the UK can be found here. There are currently no central planning guidelines for large-scale solar farms in Ireland. However a research report on planning and development for solar farms in Ireland contains some useful information and can be accessed here.

4.4. What information is available for land-owners regarding solar farms?

  • Presentations from an IFA event ‘Solar – a real opportunity for farmers?’ hosted in July 2016. The presentations cover technical, legal and tax considerations for landowners.
  • A useful article for landowners on solar farms in the Engineers Journal.