FAQs
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Solar FAQs
Q. What is solar energy?
A. Solar energy is the cleanest and most sustainable of all known energy sources. Radiation emitted from the sun provides us with a plentiful supply of energy. Solar radiation is responsible for almost all the natural processes on the earth and until very recently, the suns energy has been difficult to harness.
Q. Does it work in the UK?
A. Yes. Solar thermal (Hot Water) systems will supply heated water, even on cloudy and overcast days in summer and winter, typically delivering up to 70% of hot water demand over the course of a year.
Photovoltaic (Electric) cells do not need to be in direct sunlight to work, and will generate electricity even on cloudy days. The brighter the day the greater the energy generated.
Q. What is solar water heating?
A. Solar energy is collected by a solar collector, which is connected to your existing heating system. Using the energy from the sun, heated water can be generated for your house, factory or swimming pool.
Q. What is solar Photovoltaics (PV) energy?
A. The photovoltaic (PV) process converts sunlight, directly into electricity. This can be used directly to power everyday electrical devices.
Q. How does a solar hot water heating system work?
A. A dedicated fluid is circulated through the solar collector which absorbs the solar radiation and heats the fluid. This fluid is pumped to the storage cylinder where it heats the water and leaves it ready for use.
Q. Why install Solar Water Heating?
A. By choosing solar energy you will save on heating costs, reduce your carbon footprint, contribute to the environment and extend the life of your current heating system.
Q. Is solar water heating an alternative to my current use of fuels such as oil, gas or electricity?
A. Solar energy should not be seen as totally replacing your current fuel needs but as a supplement to reduce your fuel costs.
Q. What size of system do I need?
A. Systems sizes are determined based on variables such as hot water demand / orientation / cylinder capacity etc.
Q. Where do I position my panels?
A. The ideal position is facing due south but systems can also work with east / west facing roofs. As well as sloped roofs panels can be mounted on flat roofs, walls and the ground.
Q. What temperatures can I expect from my solar system?
A. On sunny days temperatures of 70°C to 85°C are common.
Q. Where should I go to find out more about renewable energy systems?
A. Contact MG Renewables to further discuss any questions you may have or just for general advice.
Heat Pumps FAQs
Q. What is a heat pump?
A. A heat pump is a device, which moves heat energy from one place to another and from a lower to a higher temperature. A domestic refrigerator is a heat pump. Heat is removed from the contents (the source) and discharged elsewhere (the sink). In heating applications, heat is removed from ambient air, or water, soil or bedrock and delivered to where it is needed. In cooling applications, the reverse happens and heat is removed, to be discharged to the ambient air, water, soil or rock.
Q. What is so great about heat pumps?
A. Heat pumps use a little energy (usually in the form of electricity) to move available energy as heat from A to B. For every unit of energy purchased as electricity, several units of heat are delivered. So, relating the energy purchased to the energy delivered, heat pumps can be from 300% to 500% efficient.
Q. What does a heat pump need to provide heating?
A.
There are three main parts of any heat pump system:
1. A heat source and the means of extracting heat.
2. The circuit of working fluid within the heat pump itself and a power source.
3. A distribution system to deliver the energy in the required form.
The heat source can be the ambient air, water, soil or rock. The outside heat exchanger (the collector) transfers energy as heat to the circuit of working fluid within the heat pump itself. It is preferable, in terms of maximising efficiency, to have constant temperature differences between (a) the source and the working fluid and (b) the working fluid and the sink, but this often not possible in some heat pump models.
The distribution system takes the heat from the heat pump (often as hot water) and delivers it to the end-use. Heat can be distributed within a building using underfloor pipes, fan coil units, an air handling system, or wall-mounted radiators.
It is necessary to include a power supply to the compressor to drive the heat pump. It is usually an electric motor which drives the compressor, but a gas engine is used in some designs.
Q. How does a heat pump work?
A. A heat pump works by driving a working fluid around a refrigeration circuit containing four elements; (1) evaporator, (2) compressor, (3) condenser and (4) expansion valve.
The working fluid changes from liquid to gas (evaporates) as heat is absorbed from the heat source. Later in the cycle, the working fluid condenses to liquid as heat is released to where it is needed.
Q. How could I use a heat pump?
A. A heat pump can be used where there is a low temperature source of heat. For example, heat can be transferred from a source at 5ºC and delivered as heated water at 45 to 55ºC.
Applications include space heating and cooling, pre-heating domestic hot water, heat recovery and dehumidification in both domestic and industrial sectors.
Q. Does a heat pump use renewable energy?
A. Yes, the source is usually renewable energy from an ambient heat source or waste energy. For example, with a 3:1 performance ratio, for every three units of heat delivered, two units can be from the renewable heat source and one from the electrical power supply. A heat pump, operating on a ‘green electricity’ supply from an accredited renewable source, offers emissions-free heating and then three units of renewable energy would be delivered for every one unit of energy purchased as ‘green electricity’.
Q. What are the different heat sources?
A. Ambient heat from water, air, or the ground; or waste heat from industrial processes or combined heat and power units are often used.
In air-source heat pumps, external air at ambient temperature is cooled by passing over a finned heat exchanger, thus heat is extracted into the evaporator of the heat pump. In a water source heat pump, river, lake or ground water is cooled as heat is extracted.
In the case of ground source heat pumps, the collector pipe is installed in one or more trenches or boreholes. A water/anti-freeze solution is pumped around this loop of plastic pipe, extracting heat from the ground.
The heat extracted from the ground or lake or river water is replaced by heat from the atmosphere.
Q. What are the advantages of a heat pump system?
A. Energy Efficient: Heat pumps are very energy efficient as they consume a little energy (usually as electricity) in order to deliver three or four times as much energy as heat. The ratio of energy-out to energy-in depends on the operating conditions and typically varies between 2 to 1 and 5 to 1. The overall average is called the seasonal performance factor.
Environmental: Heat pumps access renewable or waste energy and so displace consumption of conventional fossil fuels (gas, oil, coal). As electricity generation technologies improve, the emissions performance from the combustion of fossil fuels and renewable electricity generating capacity increases, so the greenhouse gas emissions associated with electricity consumption are reducing – making heat pumps even more environmentally beneficial.
Physical: Different types of heat pumps have different benefits. Ground source heat pumps have -
• No visible external equipment
• No external fans
• Quiet running
• Very little risk of accidental damage
• Adaptable to many locations.
Economics of heating houses: The running costs of a heat pump can be less than those of a traditional gas boiler heating system and definitely less than some other forms of heating (LPG, oil, electricity). The initial capital cost is usually higher than other conventional heating systems. The ‘whole-life’ cost, combining the capital and running costs, can be favourable for heat pumps compared to fossil fuelled systems – and, especially, compared with other forms of electric heating.
In addition to providing domestic heating, heat pump systems are used in commercial premises (offices, hotels, supermarkets) – often providing heating and cooling – and also in some industrial processes and applications.
Q. What about greenhouse gas emissions?
A. Heat pump systems consume energy in moving heat from one place to another. The principal use of energy in a heat pump is to generate the motive power to drive the compressor. The associated emissions depend on the power source driving the compressor. In the UK the heat pump will typically create around 55% of the greenhouse gas emissions from the most energy efficient domestic gas heating system (where the heat pump is providing space and domestic hot water heating). This is a considerable improvement.
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Testimonials
"This thanks is for the very cheerful and professional way you went about your work. The fact that nothing was too much trouble and the extra work you did came at no extra cost was a very pleasant surprise. If you ever require a reference for other customers we would be happy to oblige."
C & B Donnison Nottingham
"From my initial enquiry through to completion of a project, that changed direction several times before I finally went ahead, they were able to guide me on my way in a professional and helpful manner."
Roger Tovey, Staffs
"We had a solar panel and ground source heat pump fitted by MG Renewables during September 08. At all times I found them to be helpful and efficient. The system has now been running for 2 months and we are very pleased with it. MG Renewables have been in touch over this period to see if any other, follow up, visits were necessary. I consider this personal touch to be rare these days and important when installing new technology."
William & Rowan Booth, Lincolnshire
"Your "hands on" approach was fantastic and we are sure that will bode you well in the future. Any problem solving was solved immediately, with the minimum of fuss, which is extremely refreshing in today’s world!"
Ian & Elaine Fursland, Bucks |
