General Questions

The term ‘solar panel’ can refer to a wide range of solar technologies. It is often used interchangeably between the panels that generate electricity and those that generate heat. 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.

There are a variety of different solar PV technologies and products. The performance and cost of different products varies greatly. The most common solar PV technologies are: • Mono-crystalline silicon panels: typically the most efficient commercial solar panels at converting light into electricity • Multi-crystalline silicon panels: typically slightly less efficient than mono-crystalline panels but often less expensive • Thin film panels: this encompasses a range of technologies (including those made from cadmium telluride (CdTe), copper indium gallium diselenide (CIGS) and amorphous silicon (aSi)). These technologies are not as widely deployed but are often favoured because of their appealing appearance. Silicon-based solar panels are by far the most commonly deployed, accounting for over 90% of the global market.

The amount of electricity generated annually will depend on a range of factors including the hardware chosen, size of system, the geographical location and the direction in which the panels are installed. With the most common silicon solar panels typically 1 sq. m of panels will generate ~150W of power on a clear sunny day (that’s enough to power a laptop computer). A home solar PV system sized at 20 sq. m (~3kW) would generate around 2,600kWh of electricity a year if well-located.

Yes, solar PV systems will still generate electricity when there is daylight, so they will still function on overcast days in Ireland. In these conditions they will not be able to produce power at their maximum rated capacity (the figure in kilowatts (kW)), rather at some fraction of this figure. Solar panels will perform at their best in direct sunlight and therefore solar PV systems in Ireland will typically produce less than other, sunnier countries such as Spain.

Most solar panels are manufactured in Asia (primarily in China and Taiwan) but there are also some European and North American manufacturers. The components for solar panels and other hardware used in the installation come from all around the world.

SEAI’s research, development and demonstration programme supports Irish energy research. The programme has supported innovative projects on a variety of solar technologies, committing over €1m of RD&D funding to solar projects since 2005. The programme will be of interest to solar researchers, technology developers and those seeking to demonstrate innovative new approaches to utilising solar technology.

Non-domestic rooftop solar PV

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. Solar PV systems generate electricity only during daylight hours, predominantly around the middle of the day. For businesses with high daytime electricity demands this could be a good option. Also, around 75% of the annual energy from a solar PV system is produced from May-September. You need to consider how much of the generated electricity you will use in your building, based on the pattern of generation from the solar PV system, and the pattern of energy usage for your business. Without any additional systems, a lot of the generated electricity can be spilled (exported) to the grid, and there is currently no mechanism for generators to claim a payment for this (see question 3.4). 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. Finally, it is worth considering other options to improve the energy performance of your building, such as insulation, boiler upgrade, monitoring systems, or some other renewable generating technology.

Larger solar PV systems in a business or industrial setting will typically require planning permission. Solar PV systems installed in such a setting under 50 sq. m (and representing less than 50% of the total roof area) are exempt from planning.

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 via EXEED: The Excellence in Energy Efficiency Design (EXEED) programme offers grant support to business and industry for energy improvements and can encompass grant support for solar PV systems.

In Ireland, feed-in tariffs ensure that homeowners and businesses are compensated for surplus solar energy they export to the grid. Under the Clean Export Guarantee (CEG), introduced in February 2022, various energy suppliers offer rates ranging from 15.89c to 25.0c per kilowatt-hour (kWh) for this excess energy. Typically, a residential solar PV installation will export between 10% and 40% of the generated electricity, depending on the household’s consumption and system size. As a result, an average household can expect to earn between €100 and €300 annually in energy credits from these feed-in tariffs.