There are a variety of considerations when determining whether or not solar panels are right for your home. 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 your home. Solar PV systems generate electricity only during daylight hours, predominantly around the middle of the day when you may be at work. 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 home, based on the pattern of generation from the solar PV system, and the pattern of energy usage and occupancy for your house. Without any additional systems, a lot of the generated electricity can be spilled (exported) to the grid, and there is currently no mechanism for homeowners to claim a payment for this (see question 2.9). You also need to consider if your roof is suitable for solar PV considering the age and condition, the orientation of your house, 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 home, such as insulation, draught-proofing, improved windows, boiler controls, or some other renewable generating technology. Speaking to a BER assessor is a good first step.
Finding a competent installer is important. There are currently no formal qualifications mandated which installers must hold, but connection of the solar system must be carried out by a Registered Electrical Contractor. SEAI’s advice would be to contact multiple installers or developers to get a range of quotes. A good place to start is the Renewable Installers Register which identifies installers that have received accredited training.
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.
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’). Other optional components are an immersion diverter switch, battery, or energy meter (see questions 2.6 and 2.7 for more information).
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. The most important consideration for homeowners is that the water tightness of your roof is not affected by the installation. Installers should not be permitted to drill into roof tiles to connect the PV panels, as this could lead to future leaks in your roof.
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. Finally, a more complicated option is to install a PV system which does not face south, but faces west or east. This will provide more energy in the morning or the evening when you have a greater demand to use it. However, an east- or west-facing PV system will generate less energy over the year than a south-facing system.
This is a more complex way of storing any potential exported electric energy. Adding a battery to your solar PV system means the battery will charge when the PV system is generating electricity which isn’t being used, and then discharge when you need it next (normally that evening/night). A battery can increase the percentage of solar PV electricity you use in your house. However, adding a battery to the system will increase the cost of the PV system and some energy is lost in the battery during the charge and discharge cycle.
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’). It is up to energy suppliers to decide whether they wish to offer such a scheme to customers.
PV systems are low-maintenance, but not zero maintenance. The most important aspect is to monitor the performance of your system regularly. This could simply be a routine check of your inverter to see that the system is operational (e.g. no red blinking lights) and that the energy meter is increasing each day. You should get an idea from your installer about how much the PV system should generate each year, and see that your system is generating close to that amount. Some suppliers will provide you with access to this information via your smartphone. The most common point of failure is the inverter, which may need to be replaced at some point in the PV system’s lifetime. The solar panels themselves are extremely robust, but consideration should be given to cleaning them every few years to maintain their performance. If you live near the sea or a main road more regular cleaning may be necessary.