Solar Electric (Photovoltaic/PV)

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 daylight 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.

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 is 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 30 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).
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.

Air to Water Heat Pumps

What is a Heat Pump and what is an Air-to-Water Heat Pump?

Heat Pump technology is being used in one of the most common appliances in our homes – the fridge. The principle of a heat pump is to move energy by the means of electricity, refrigerant gas and compressor and it can do both HEATING and COOLING. We are extracting it from a warmer ambient i.e. the food in the fridge; and dumping it, this process is called COOLING. Or harvesting energy from the air outside our homes and passing it to the air and hot water tank inside our homes and this process is called HEATING. We are transferring the heat obtained to the water in our systems, therefore the name AIR-TO-WATER heat pumps.

How does an Air-to-Water Heat Pump Work?

1. Air passes the heat exchanger outside called EVAPORATOR and the refrigerant gas absorbs heat from outside air and evaporates
2. The vapour passes into the compressor and by compression increases its
temperature and pressure
3. Hot vapour is condensed in the 2nd heat exchanger, the heat being passed via water onto Heating or Domestic Hot Water system
4. The liquid refrigerant passes back through the expansion valve, reducing its pressure ready to start the cycle again.

What is the efficiency of an Air-to-Water heat pump and what heating systems complement it? What is COP and SPF (SCOP)?

A heat pump’s efficiency is often referred to as a “Coefficient of Performance” (COP) and all heat pump manufacturers are giving this value for nominal conditions of 7 °C outdoor temperature and 35 °C flow temperature.
The Coefficient of Performance (or COP) describes the ratio of electrical power used to heating power produced under fixed input and output conditions by the heat pump unit only. A COP is used for examining the performance of a heat pump unit at ideal test conditions, usually in a laboratory.
COP of 4 means for every 1kW of electrical energy used, 4kW of useful energy is produced – a net 3kW of useful energy will be ‘free’ generated by the heat pump.
COP decreases with falling ambient air temperatures and rising flow temperatures
The Seasonal Performance Factor or Seasonal Coefficient of Performance (SPF or SCOP) describes the ratio of the amount of electrical energy used by all components associated with the heat pump system, to the amount of heat energy delivered to the heating system, over a long period of time (e.g. season or year).
SPF is a better indicator of performance for the purposes of examining the “real-life” performance of a heat pump than COP and takes in account the type of heating system installed.
Under the new EU regulation SEAI has implemented this in the New Heat Pump Methodology and by using their proposed Heat Pump Calculation Tool we can get accurate SPF’s based on data that every heat pump manufacturer has to provide.
SPF values may vary depending on the type of heat emitters used and aiming for a low flow temperature will result in high SPF figures. Ideally with an Air-to-water heat pump we should use an UFH – underfloor heating system because this only requires flow temperatures up to 35 °C, resulting in SPF’s over 5.
We can also use low temperature radiators, aluminium or steel panel or fan coils which require flow temperatures up to 55 °C, resulting in SPF’s around 400%. Comparing these two figures we can see that the UFH system compared with a Low temperature radiator / fan coil system is circa 20% more efficient.
The DHW production efficiency though for any heat pump it is not that high due to the high flow temperature required to heat the DHW cylinder. This figure is in around the 200% mark and takes in account that most air-to-water heat pumps require an electrical immersion to raise the temperature in tank to 60 °C, as an anti-legionella protection.
Both Monobloc (water connection) and Split (refrigerant connection) heat pumps have their advantages and where the Monobloc scores well for the ease of installation the Split has slightly higher efficiencies and can be used with integrated cylinder units, giving a more compact and small footprint solution, having all components built-in the indoor module.

How can an Air-to-Water heat pump be integrated in a new dwelling and help to achieve Part L compliance with the Building Regs?

At an early stage of the project the designer of the system has to take in account the type of heating system that will be installed working closely with the BER assessor. The reason is to make sure that the Air-to-water heat pump can comfortable meet the heating load of the house and provides enough renewables thermal contribution to meet Part L requirements; heat loss calculations should be done in accordance with current standards and regulations. In most new dwellings the DHW production is going to be done off-peak heating demand, therefore we can prioritize this during the night and mid-day when the heating demand is very low. As most air-to-water heat pumps are equipped with an electrical back-up heater, this can be conditioned to be used for heating, only if external temperatures fall below a specified point. This point is called equilibrium temperature and usually is set at -3 °C but in most cases this is not used for heating at all.
Manufacturers with tradition in the heat pump industry have their Air-to-water heat pumps designed specially to suit the European climate working even at outdoor temperatures of -25 °C. One key thing to remember is that the “heart and blood” of any heat pump, whether it’s Monobloc or Split, it’s the “compressor and refrigerant”. Therefore make sure before buying into any systems that the manufacturer of the heat pump has also got experience, knowledge and tradition in this field and the product complies with the Energy Labelling & Ecodesign directives.

What is a refrigerant?

Heat pumps can heat or cool down an indoor space and heat up a DHW cylinder by the means of a refrigerant gas that can evaporate even at -25 °C. The refrigerant inside the piping helps in transporting this energy between the inside and outside of your home. This is the reason why there is an indoor and outdoor unit. The substances used have such properties that the process is the most energy efficient and achievable with technology, which is safe to use. There are a few types of refrigerants that Daikin has invented and still owns the patent on them, such as : R410 and the most environmental friendly & energy efficient R32.

Solar Hot Water (Thermodynamic)

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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