Solar Electric (Photovoltaic/PV) FAQ


Does PV (Photovoltaics) work in Ireland and the UK?


There is an opinion out there that Solar technology would not work in Ireland and the UK, this stems from people thinking that we don’t get enough sunlight in the Summer, never mind the Winter.

This however is not true, Photovoltaic cells work on sunlight as opposed to the heat from the sun. In fact, Ireland has the same annual Irradiation levels as many parts of Central Europe, ranging from 1200 kWhr/m2/yr in the south of the country to 1000 kWhr/m2/yr in the north of the country, a good average for the entire country is 1100 kWhr/m2/yr.

If you consider our typical winters would not be as bad as many parts of Central Europe, our mild climate is ideal for Solar installations, as we never get too hot or too cold and we have good light levels for a large part of the year.

Why should I use PV?


PV IS CLEAN, RELIABLE SOURCE OF ENERGY - Solar PV uses the sun’s energy to generate clean green electricity that can be used directly in place of conventionally generated power in your home or business. It is one of the easiest and most beneficial renewable energy technologies to add to any building, whether commercial or domestic.

SOLAR PV SAVES YOU MONEY - The Feed-in Tariff (FIT) means you get paid for all the solar electricity you generate – for 20 years, it is also index linked. You get paid extra for the electricity you don’t use that is exported to the national grid.

PV GIVES YOU ENERGY SECURITY - You not only save money on your electricity bills, but you are protecting yourself against inevitable price rise from energy suppliers and potential energy shortages in the future.

PV CUTS CARBON EMISSIONS - Each unit of electricity generated by a solar PV system reduces the amount of CO2 that is emitted from conventional power stations. Over 25 years, a 1kWp PV array it will generate over 18,000 units of electricity and save over 10 tonnes of CO2.

PV IS VERSATILE - Solar PV panels can be installed at almost any location; usually mounted on a building’s roof, but they can also be integrated into the fabric of the building, replacing traditional roofing, glazing or cladding materials, or on simple ground-mounted structures.

PV IS MAINTENANCE FREE - PV panels are usually cleaned quite adequately by the rain. As the system has no moving parts it requires no general maintenance and the only projected cost is the replacement of the inverter at some time during the lifetime of the system.

How do you know that the system is taking power from the panels and not the grid?


The system will take power from the PV panels “first” naturally and will only draw power from the grid if there insufficient power available from the PV panels. The flow of electricity in a system is determined by the electrical potential at all points in the system. The simplest analogy is to think of the flow of electricity in a network of conductors connected to the grid as being like the flow of water through a network of pipes connected to a water main. If there is more pressure in the network of pipes than in the water main, water will flow out into the water main – and vice-versa.

What is the lifetime of PV modules?


PV modules have a manufacturer’s warranty of 25 years and a working lifetime of 40 years and beyond. As the photovoltaic effect is a naturally occurring phenomenon, there is nothing to say that the panels will not continue to create electricity for as long as they are in sunlight. A PV system that is designed, installed, and maintained well will operate very efficiently for at least 25 years. The best way to ensure and extend the life and effectiveness of your PV system is to purchase quality components from a reputable company who will guarantee that your system is correctly installed and commissioned.

How much electricity does a standard domestic house use?


An average house is considered to be 150m2 /1,614sq ft and uses approximately 3,300 kWh of electricity per annum. An energy efficient house uses approximately 1,960kWh per annum. A 1kWp system generates 1,100kWh of electricity per annum (statistics from CareyGlass Solar’s existing installations in Ireland).

What is a Feed in Tariff and what is it worth to me?


The Feed-in Tariff (FIT) was introduced by the Government in order to make solar PV systems a more attractive investment and to encourage the generation of more “green” electricity.

The feed-in tariff (FIT) pays a cash premium for all the electricity generated by your solar PV system, whether you use it in your building or it is exported to the grid. Surplus electricity that you don’t use will benefit from an additional export payment. You also save money on every unit of electricity you use in the property that you would otherwise have bought from your electricity supplier.

Based on current electricity prices, solar PV systems can expect to pay for themselves in 7 to 8 years and after that, all the income is pure profit – and for home owners it is even tax-free. What is more, as FIT payment rates are index linked and as electricity prices continue to rise, the return on your investment will also rise. What other investment can offer you a 20 year project Internal Rate of Return of 13 to 15%?

Basically, the electricity generated by a solar PV system qualifies for two elements of payment:

And any PV system owner can benefit from the FIT – householders, farmers, landlords, businesses or public bodies – whether schools, leisure centres or public libraries.

The generation tariff is paid for every unit of electricity that is generated, whether it is used at the premises or not.

The export tariff is an additional payment, made for each unit of electricity that is not used at the premises but is exported to the national grid.

FIT payments are administered by the licensed electricity supplier that the system is registered with. All FIT registered systems are required to have a generation meter to record the actual amount of electricity that is generated by the PV system. In order to qualify for export tariff payments, PV systems require an export meter that records how much surplus power is not used at the premises.

What rate does the feed-in tariff pay?


The FIT varies between the UK and Northern Ireland.

The UK: The FIT payment rate depends on the size of the system (measured as kWp) and is paid per unit of electricity generated (or kWh). The FIT rates for multiple installations (over 25 systems) are 90% of the above rates for installations in each size category.

Once your PV system has been registered, the electricity generated will qualify for the appropriate FIT rate for the size of the system for the full 20 year duration of your FIT contract, with annual inflationary rises in line with Retail Price Index. For privately owned systems, these payments are also tax-free.

What about the EPC Certificate?


As from April 2012, new solar PV systems only qualify for the full FIT rate payments if the property meets an Energy Performance Certificate (EPC) rating of D or above. However, the addition of a PV system to a property can be taken into account in the EPC survey and could be enough to raise the rating from an E to a D, such that it still qualifies for the full FIT rate. Systems on properties with an EPC rating of less than D (even taking the PV system into account) will qualify for the same FIT rate as stand-alone systems (currently 7.1p).

However, as from 1st December 2012, certain non-domestic community organisations and education providers may be exempt from the D level EPC requirement. Eligible community organisations may also be able to apply for a “tariff guarantee”.

Can you give me an example of the rates of return from the PV?


Assessing the financial return from a PV system requires consideration of various factors, including FIT income, your pattern of electricity use and electricity price trends. However, under current FIT rates and typical electricity prices:

A typical 4kWp domestic roof-top system could cost you just £7,000, Over the 20 years of the Feed-in Tariff you could expect FIT payments of £600 per year (including exports) that rise annually with inflation. In addition, you can expect to make a saving of some £220 on your annual electricity bills. This, combined, gives you payback in about 7.5 years and a 20 year project Internal Rate of Return of around 13%.

A typical 30kWp small commercial roof-top system could cost you about £37,500. Over the 20 years of the Feed-in Tariff you could expect FIT payments of £3,800 per year (including exports) that rise annually with inflation. In addition, you can expect to make a saving of some £1,400 on your annual electricity bills. This, combined, gives you payback in under 7 years and a 20 year project Internal Rate of Return of around 15%.

A typical 100kWp large commercial roof-top system could cost around £115,000. Over the 20 years of the Feed-in Tariff you could expect FIT payments of £12,000 per year (including exports) that rise annually with inflation. In addition, you can expect to make a saving of some £3,800 on your annual electricity bills. This, combined, gives you payback in under 7 years and a 20 year project Internal Rate of Return of around 15%.

Northern Ireland; The system in Northern Ireland employs a Renewable Obligation Certification (ROC) system, this is very similar to the UK whereby it is index linked and government guarantee for a period of 24 years. The current rates are as follows; Photovoltaic (PV) Up to 50kW 4 ROCs £176.40/MWh. 50kW – 5MW 2 ROCs £88.20/MWh.

Have you got a sample case study from Northern Ireland?


A typical 4kWp domestic roof top system could cost you £7,000, you can expect to earn £590 per year from your ROCS, that’s an expected saving of £268 and a 5 to 7 year payback.

What if I don’t have grid access?


If you don’t have access to a grid, you can consider an off-grid or stand-alone system. In a stand-alone system, there is no connection to the regional electricity supply, and the system provides all the electrical needs of the property.

Stand-alone systems are used in rural properties and out-buildings and by remotely sited equipment used in communications and instrumentation, broadcasting, navigation aids and environmental monitors when it is impossible or uneconomic to connect to the utility company.

A bank of batteries is charged by the solar array during the hours of daylight and the energy stored is utilized whenever required, even at night. The system is often enhanced by a diesel motor-generator to supply peak demands or during periods of poor light conditions.

A typical 49kWp system will cost you approximately £56,700, you can expect to earn £7,232 per year from your ROC’s that’s a saving of £4,592 and a payback period of 7 years.
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Solar Hot Water (Thermodynamic) FAQ


Will the Thermodynamic system work in rainy overcast days?


Yes the Thermodynamic Solar system will work in any weather conditions even down to -5 degrees outside.

How does thermodynamic solar work?


Thermodynamic solar is a principal of using refrigerant gas to extract heat from the atmosphere and convert it via a heat exchange process to the water used for bathing , washing, etc.

Does this system have Legionella control?


Yes it has an electric element which can boost the water to 60 degrees C which prevents Legionella if needed.

Do I need to replace my existing cylinder?


No if you have a good quality insulated cylinder we can retrofit into this cylinder.

Do the panels have to be fitted south facing?


No the panels can be fitted at any orientation but preferably south facing is best.

Do I need any special power supply?


No just a normal socket will do.

What is the difference between this system and conventional solar tubes and solar panels?


Solar tubes and solar panels only work with sunshine to produce hot water to 55 degrees , this system will produce 62 degrees hot water in any weather conditions.

Is there any risks of freezing pipes?


No this system using a refrigerant gas in the pipes which will never freeze or over heat.

How does this system guarantee hot water 365 days of year?


By combining the solar gain outside and the mini heat pump compressor raising the temperature of the refrigerant to 110 degrees C , this insures the water in the cylinder will always be heated to 55 degrees C.

Is this system guaranteed?


The panel and cylinder carry a 5 year guarantee and the thermodynamic block carry a 2 year guarantee , we also offer a 2 year guarantee on labour.

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Heating & Hot Water (Heat Pump) FAQ


What is a heat pump?


A heat pump extracts low temperature energy from the environment and increases its temperature for heating purposes. Heat pump efficiencies are normally quoted as the coefficient of performance of the system, these are typically in the range 3 to 5. In other words, extracting heat from renewable sources requires just 1kW of electrical input in order to generate 3kW to 5kW of heating output. Heat pump systems therefore, are 3 to 5 times more efficient than fossil fuel boilers and are more than capable of warming a house completely, even during the lowest winter temperatures. The increasing popularity of these heating systems is reflected by their overwhelmingly successful application in the cold climates of Scandinavia.

What about Legionella?



The legionella bacteria is a natural inhabitant of water. Temperature is of great importance for the growth of legionella. Especially temperatures between 40°C and 50°C may lead to colonization of the bacteria.

As Daikin does not use water in its air conditioning systems, no harm for humans can be caused. In chilled water systems for industrial purpose, the legionella bacteria can not live because of the low temperature of the water in the closed circuit.

All Daikin systems that produce domestic hot water are equipped with an anti-legionella tank and a weekly disinfection cycle that prevents bacteria build up in stored water. Some of these hot water tanks however are based on the flow-through principle, which means a weekly thermal disinfection is not necessary.

If you are looking to have an absolute fresh water feeling, have a look at our ECH20 thermal store. Unlike taditional hot water heaters, the ECH20 thermal store instantly heats water passing through the tank. This process avoids prolonged water storage, and significantly increases the safety and quality of your hot water. Equipped with an anti-legionella thermal store, our ECH20 domestic hot water heat pump ensures you always have hot water that is fresh and healthy.

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