What are solar PV panels?

PV or photovoltaic solar panels transform daylight into free power/ electricity.

They work totally uniquely in contrast to solar hot water collectors. At the point when sunlight strikes a PV solar panel, a DC electrical current (direct current – like in a battery) is produced. On the off chance that you have a few of these boards on your rooftop in series, the current becomes enormous. This DC current then ventures down to an inverter, where the electricity is converted from DC to AC (alternating current – like the electricity in your house socket). In Ireland all homes use AC power to run day to day electronics in the house such as your TV, phone charger, microwave, toaster, oven, refrigerator, radio and so on.

It is only possible for solar PV systems to generate electricity when there is daylight, predominately around the middle of the day. In Ireland, around 75% of electricity is generated from May to September. In case that the electricity hasn’t been used in the home it is transported to the grid.

Based on comprehensive analysis and research by SEAI, maximising the amount of solar electricity you use in your home is in your interest, which can be achieved by customising the solar PV system to meet the demand of your home. However, there will be an equilibrium between the increased costs for batteries or alternative energy storing systems and the reduction of excess energy exported to the grid.

The benefits of PV solar panels

Free and abundant – Solar energy provided by PV solar panels is supplied from nature. It is completely free and abundant.

Significant savings – A solar PV system can help you save on your domestic electricity bill on average €200 to €800 per year, which will make a significant difference to your home running costs. The operating and maintenance costs of PV solar panels are also considered low compared to other renewable energy systems.

Less maintenance – PV solar panels have no moving mechanical parts unless there are sun tracking mechanical bases. Therefore they require less maintenance as a result of much less breakages.

Long term ensured output – 25 years from the time of installation are guaranteed for the output of your PV panels, while on average you can expect payback for your PV system from 6 to 9 years depending on the size and orientation of the system installed. You can calculate your payback here https://www.seai.ie/tools/solar-electricity-calculator/.

High efficiency – We select only the highest output solar panels of the finest quality for your home. The PV solar panels are usually roof mounted facing south to achieve maximum output. In case of flat roofs or on the ground we will use special mounting kits to maximum the energy output for you.

High Building Energy Rating (BER) - A Building Energy Rating or BER is an energy label with accompanying advisory report for homes. The rating is a simple A to G scale. A-rated homes are the most energy efficient and will tend to have the lowest energy bills (SEAI, 2021). Potential buyers or tenants will take energy performance into consideration when they make a purchase/ rental decision which is embodied by BER. It is almost impossible to get an A BER rating without a PV solar system. PV solar panels generates free electricity without the use of fossil fuels, which will raise your BER and make your house stand out in the competition in your area.

How do PV solar panels work?

PV stands for photovoltaics where the photo means light and voltaic means volt or electricity. Simply put, a PV solar panel works by generating a flow of electricity through photons (particles of light) knocking electrons free from atoms. PV solar panels consist of many small units called photovoltaic cells.

A solar panel that converts daylight into electricity is made up by many photovoltaic cells linking together. Each photovoltaic cell is composed of two slices of semi-conducting material which usually is silicon. Electricity is generated by the material when light shines on it. Only a tiny amount of electricity is generated by one photovoltaic cell, thus many of them are arranged together to form a panel. Typically, a domestic PV solar system could have anywhere between 5 to 20 solar panels to form a bank or an array, and each solar panel could have 60 solar cells in it. For commercial PV solar systems, there could be hundreds of solar panels.

After electricity being generated in PV solar panels, it travels down by a cable to an inverter in the attic, then the inverter convers the electricity from DC to AC electricity, which can be used in almost every home around the globe.

Once AC power has been converted from DC power, it is sent to the fuse board which goes to all the power outlets in your home. If excessive power is being generated by the PV solar panels than what is required, the excess can be diverted to your electric immersion to produce hot water for free. If there is still excess when the water cylinder is hot enough, the excess will then be sent to the national grid. This system will reduce your electricity bills significantly.

However, if the PV solar system is only generating partially the power that your home needs, the rest will come in from the national grid as it would normally. Basically, every home is already connected to the grid which is where you get electricity from the ESB. So, you can rest assured that you will see a dramatic reduction in your electricity bills while your home is supplied with sufficient electricity and an increase in your BER and green credentials.

What different types of solar PV panels exist?

There are a wide range of different solar PV innovations and technologies. The performance and cost of various products differs extraordinarily. The most commonly used solar PV panels are mono-crystalline silicon panels, multi-crystalline silicon panels, and thin film panels.

Typically, the most efficient commercial solar PV panels to convert sunlight into electricity are mono-crystalline silicon panels. Multi-crystalline silicon panels are usually slightly less efficient than mono-crystalline panels, but they often cost less. Thin film panels encompass a range of technologies including those made from cadmium telluride (CdTe), copper indium gallium diselenide (CIGS) and amorphous silicon (aSi)). These materials are not as commonly used but are often chosen because of their appealing appearance. Silicon-based solar PV panels account for over 90% of the solar systems in the world, which are most widely deployed by far.

Does Ireland get enough sun for solar panels to be efficient?

Yes! Ireland does get a fair amount of rain, but the solar PV system generates electricity in daylight. If there is daylight, free electricity will be generated. The solar panels still function on overcast days. However, the brighter the day, the higher the output.

What country has embraced solar panels the most in the world?

The leader in solar PV generation is China. Solar PV farms can be seen as utility scale systems. Nearer to home, in the North, you will see heaps of commercial buildings or homes with solar PV panels installed on the roofs. Individuals for the most part install solar PV panels to meet some of their energy needs, reduce their carbon footprint, and help protect the environment.

How much electricity will I use from solar panels versus what I use from my electricity provider?

To get the best value for the electricity, you want most of the energy used within your home rather than spilling onto the grid or exported. Usually this means your solar PV system should provide around 1/3 of your electricity needs, otherwise you will need to install a storage system (a battery) that will allow you to store the excess electricity when there is no daylight (e.g. at night).

Can I install a solar PV system if my roof is not South-facing?

Research has found that South-facing solar PV systems produce the most electricity in Ireland. However, South is not always the best roof orientation for solar PV panels. For example, East-facing PV panels produce most power in the morning, while West-facing PV panels produce most power in the evening. Therefore, combining East-facing and West-facing panels in one solar PV system will provide you high power output in early mornings and late evenings. This perfectly suits people who work away from home during the day and require more power in the morning and evenings. This use pattern of electricity is ideal for installing East-West facing panels, for example, the Irish diary farms who installed solar PV systems usually went with East-West facing panels. This is because the high energy consuming milking equipment is frequently used in the morning and evenings. 

Power output wise, South-facing panels will produce approximately 16% more power than East-West facing panels, while South-West and South-East facing panels can produce almost as much power as South-facing panels. On the other hand, it is possible to boost the power output of East-West facing solar panels to match up with South-facing ones at very little cost. Moreover, since East-West facing solar panels will never be all at the maximum output at any time, you can have a higher power rating for the panels than the inverter (DC over-sizing). This can save money with a smaller less expensive inverter.

How can I maximize the usage of the amount of electricity generated?

The easiest way to increase the percentage of used electricity generated is to design the solar PV system to meet the electricity demand of the house. However, this may result in a very small PV system being installed if there is low electricity demand during the day.

Another simple way is to install a divert switch to divert any excessive electricity to heat your hot water in the immersion tank. This enables you to use the excessive energy generated later which is stored in hot water.

On the other hand, a more complicated method is to install a PV system that is not South-facing. An East-West facing PV system will provide more energy in the morning and evenings, although it will generate less energy output over time.

What about a battery storage system?

A solar battery bank is another way to store any potential exported electricity. Installing a solar battery bank in your PV system means the power bank will charge when the system is generating excessive electricity that is not being used, and then when you need it next, usually in the evening/ night-time when there is no sunlight, the battery will discharge and provide electricity stored. A battery will increase the usage percentage of the electricity in your home that your solar PV system generates, although it will increase the cost of the PV system in the meantime.

Does my home solar PV system require maintenance?

Solar PV systems are low maintenance. Essentially, you need to monitor the performance of your system regularly which can be done by checking your inverter routinely to make sure that the system is operating with no errors and that the electricity meter is increasing every day. Furthermore, you should get an idea of how much electricity your PV system could generate yearly from the installer and compare with how much your system generates. If there is a huge gap between the expected and actual amount, in most cases there is a failure in the inverter which might need a replacement at some point in the lifetime of your PV system.

The solar PV panels are exceptionally robust and are unlikely to break down. But some cleaning is needed every few years to maintain their performance, especially if you live near the sea or a main road then more frequent cleaning will be required.

What grants are available for solar PV systems in homes?

SEAI Solar PV Grant - Support is available to all owners of dwellings built and occupied before 2011 and where SEAI have not previously provided support for solar PV system at that address. The homes energy performance following installation of solar panels must be BER C or better.

Home Renovation Incentive (HRI) - Some 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.

Better Energy Communities - SEAI’s Better Energy Communities program can provide grant support to community projects for the installation of domestic solar PV systems provided they are done so as part of a package of other energy improvement measures including energy efficiency.