Frequently Asked Questions (FAQ)

 

What is renewable energy?

Renewable energy is energy that has been created from sources which are not finite. The vast majority of energy that the world uses today comes from burning non-renewable sources i.e. fossil fuels like oil, gas and coal which took millions of years to form. The supplies of these substances have been fast depleting ever since the Industrial Revolution. It is very important that we change our attitude to our use and conservation of energy and also start using renewable sources. The sun rises 365 days a year and doesn’t cost a penny! So it’s time we started harnessing its potential.

Why should I invest in a renewable energy system in my home?

Although the initial costs of installing a green energy system in your home are usually higher than conventional methods, they will save you money in the long run because they operate much more efficiently. For example, heat pump systems often achieve a Coeffiency of Performance of 3 or 4 which means for every unit of energy put in, 3 or 4 units are produced, rather than the conventional 1:1 ratio.

In addition to this, energy prices have risen significantly in the last few years mainly due to growing global demand. Not only is climate change a distinct threat, but diminishing fossil fuel supplies mean that what is left is more expensive, and is increasingly hard to extract for either physical or political reasons. Gone are the days of abundant North Sea oil and gas supplies; the UK has been a net importer of energy since 2004. By installing a microgeneration system in your home you can safeguard yourself against rising prices whilst giving yourself peace of mind with energy security.

Commonly asked questions on Solar Panel systems

How much money will I save using solar PV panels?

The amount you can save (or make) from using solar panls is fully dependent on a number of variable factors.

In the case of solar PV the saving you make will be affected by the size of the system that is suitable for your house which will dictate the maximum output which your array can produce in optimum conditions i.e. on a very sunny day. This is measured in Kilowatt Peak (kWp). So a 2.5 kWp system could provide up to 2.5kW at any one time, but whether this maximum potential is reached will depend on the weather conditions at the time. During times of no energy output from your solar panels (e.g. at night time), you buy from your electricity supplier as normal.

How much you save will depend on the efficiency rating of your domestic appliances, and your personal contributions to energy saving through your own behaviour. Why not put your washing machine on during the day when you are generating free electricity? When solar PV panels are installed on your home you will normally be given a digital monitor which will tell you how much electricity your system is supplying. Most people who get solar panels start to really notice where they are wasting electricity, and invent ways to save!

What are the costs to get solar PV systems installed?

This depends on the size of the system but it will normally range between £6,000 and £15,000. Ultimately the size of your house, your energy consumption and the type and number of solar panels you purchase will affect the final price.

How long is the payback period for solar PV panels?

A 2.35 kWp system consisting of 10 panels could pay for itself in as little as 8 or 9 years. This is thanks to the generous Feed-in Tariff (see below) and the money that you will save on your bills as some of your electricity will come free from your solar panels!

I’ve heard of government grants to help fund renewable energy systems, what are they?

The Feed-in Tariff has replaced the British government’s up front grant schemes as it believes it offers a better incentive package to those people who wish to install solar panels. The benefit of the FITs scheme as opposed to the grants, is that the tariff does not drain the public purse. This is because the Feed-in Tariffs are paid by the electricity companies and not by the government directly.

 

What is the Feed-in Tariff (FIT)?

The Feed-in Tariff is a government-backed scheme to encourage the uptake of renewable energy technologies in Great Britain. The government has made commitments to ensure that a larger proportion of energy used by the population comes from renewable sources. As such, the Feed-in Tariff presents an excellent investment opportunity to anybody who has a roof or some land that is suitable for solar panels.

See our Feed-in Tariff section for more information.

 

What does ‘MCS accredited’ mean?

 The UK government has set up the Microgeneration Certification Scheme (MCS) to ensure that good practice standards for renewable energy installations are met industry wide. In order to receive the MCS mark of approval, a company must show that in the case of domestic installations it meets stringent guidelines in areas such as quality management, technical competence and Health and Safety. It must also be a member of the REAL Assurance Scheme; a specialised consumer code of conduct for microgeneration suppliers.

In order to be eligible for the Feed-in Tariff or Renewable Heat Incentive, it is necessary that the installation is done by an MCS-certified installer using MCS-approved equipment.

 Altereco is fully MCS accredited and will always use MCS-approved equipment.

 

What does photovoltaic mean?

Photovoltaic comes from the Latin word ‘photo’ which means ‘light’, and ‘voltaic’, meaning ‘producing electric current by chemical action’. PV panels use the chemical silicon with solar radiation to create electricity.

 

How do solar photovoltaic (PV) panels work?

Solar PV panels contain silicon which reacts with light causing electrons to move thus creating a direct current. This current is then fed though an inverter which changes DC current into AC current which can operate your appliances from the electrical sockets in your home.

 

What happens to my solar panels if there’s a power cut?

Unfortunately, if your PV system is grid linked, it will not provide you with electricity during a power cut. Although your panels may still be producing a current, it would not be safe to let it flow into the grid whilst there may be engineers working to fix a fault. As such your solar panels will automatically disconnect from the grid in the case of a power cut, and reconnect shortly after power is restored.

If you are off-grid, your power supply will not be affected in the case of a power cut.

 

I’ve heard that it takes many years for solar panels to pay back the energy and environmental cost that was used in their production and transport, is this true?

Quite simply, this is a myth. The US Department of Efficiency published a report in 2004 on this topic which can be read here. To summarise the article, the researchers found that for monocrystalline silicon modules (regular solar PV panels like the ones we use at Altereco), the actual energy payback time is 3.3 years, including the energy used to make the aluminium frame and the energy to purify and crystallise the silicon.

As for the transport, many of the silicon cells used in all PV panels are originally produced in China. There are, however, many modules which are assembled in the EU and we endeavour to use these where possible if this is important to you. Even so, the carbon produced in the bulk shipping of solar panels from abroad would still soon be offset by their zero carbon performance and long life span.

 

Do I need planning permission to install solar PV on my roof? 

*Update June 2011* Bristol City Council has recently published some guidance on planning permission for solar panels which can be read here.

Planning permission is not normally required for roof-mounted solar panels, but the rules differ if the property is a listed building or in a Conservation Area. In its effort to encourage the uptake of microgeneration, the planning rules have relaxed slightly in recent years with regard to renewable energy installations. It is always advisable to check with your local planning authority before works take place. Altereco can offer specialist advice for solar projects undertaken on listed buildings.

 

What is the difference between solar thermal and solar PV?

Solar thermal panels create hot water for your baths and showers.

Solar PV makes electricity for your sockets so you can boil a kettle, listen to the radio and use your computer!

 

How does the electricity that comes from the National Grid work with my solar PV system?

Once your panels and your inverter are installed you will notice no difference in the way you use electricity. You won’t have to switch the panels on or off, or maintain them in any way. You just carry on as normal. If your solar panels are producing electricity when you switch on the kettle for example, that electricity will flow straight to it and power it.

If you want to use the kettle, the electric oven and the dishwasher all at the same time there may not be enough power from your solar panels alone, in which case your supply will automatically be topped up from your regular electricity supply. You won’t notice any difference at all, until the bills come through and you realise how much you have saved!

 

What happens if I install solar PV panels on my home, then move house?

To carry on benefitting from the Feed-in Tariff that originally went with the installation the renewable energy system must stay with the property. You could of course choose to take the panels with you to your new house and have them reinstalled but you would lose the tariff rate that you are on.

As the UK moves forward to a low-carbon future and electricity prices rise, it is highly likely that any energy efficiency measures or renewable technologies will make a house more attractive to a future purchaser. And don’t forget, as the Feed-in Tariff is payable for 25 years, if you move out before then, the new owner can look forward not only to significantly lower bills but also to actually being paid by the electricity company until the 25 years are up! Can’t imagine they would need too much persuading!

 

Does adding solar PV panels add value to my property?

A Dutch study performed on behalf of the Royal Institute of Chartered Surveyors (RICS) indicates that buyers are willing to pay a premium for houses that have been labelled as energy efficient.

 

Do I need a south facing roof to install solar PV?

It doesn’t have to be facing due South, a system would still work if installed within 90 degrees of South (i.e. East or West). Having said this, a South facing, unshaded roof would offer the best yield and the further East or West you go, the more significant the loss in output.

 

The UK is dark and rainy! Aren’t solar PV panels more suited to warm, sunny countries?

Not necessarily. PV panels can still produce electricity on a cloudy day. Germany has a climate similar to that of the UK and is host to an extremely successful solar PV industry. Perhaps surprisingly, PV panels actually become less efficient at very high ambient temperatures, which is why a well-ventilated system is essential. This means that the UK climate is very well suited to solar panels compared to very hot places.

 

I’m building a new property from scratch. Are solar PV panels for me?

You are in the privileged position of being able to design a roof which would be ideal for solar PV, large and south facing with a 37 – 45degree pitch. It would be worth your while to consider installing a ground or air source heat pump too to save money on your future bills.

 

My roof is half shaded by trees and tall buildings. Will solar PV panels work?

Shading can create a problem as the electrical circuit is wired in series. Shading means the current is interrupted, creating a load which can vastly reduce output from you solar panels. Our renewable energy specialists can advise you on your options to get around this issue. One of the ways this can be done is by using micro-inverters which allow for each solar PV panel to work independently.

 

How much of my family’s electricity needs will be met by solar PV panels?

The amount of electricity your system delivers depends on how much you use and how big it is.

According to the Energy Saving Trust, an average household uses 3,300 kWh annually. It is difficult to say how accurate this is, as for instance, some households use gas for cooking, others electric. A typical solar panel system could meet a significant proportion of this average demand, well over half. This will also depend on your behaviour and whether you can optimise the output of your solar generated electricity, for example by using the washing machine in the day when the solar panels are working. 

Can I heat my water with solar PV panels?

In theory it is possible but it would be very inefficient to do so. You are better off with a solar thermal system. We are working towards accreditation for this technology but if you require an update then call us on 08456 718 441.

What happens at night time when there’s no sunlight?

Your PV panels will not produce electricity at night. Your home will be supplied by electricity from the grid as normal.

 

What is the life expectancy of a solar PV panel?

The manufacturer’s warranty that comes with the solar panel is normally 10 years product warranty and 25 years performance guarantee of up to 80% efficiency. However, it is likely that the panels could continue working for many years afterwards, albeit with a slight drop in efficiency.

 

Do I have to clean my solar PV panels?

Rainfall will normally be enough for the panels to operate efficiently but they may benefit from a proper clean every year or so.

Ground source heat pumps

 

What is a ground source heat pump?

A ground source heat pump uses naturally occurring thermal energy from the ground to provide space and water heating. Pipes are buried in the ground and pumped with a mixture of water and antifreeze. This liquid collects low temperature heat from the ground and feeds it into a heat compressor which raises its temperature to a useful level for hot water and heating. The liquid then continues around the loop, collecting heat and delivering it to the exchanger.

Although they do require an electricity supply to operate, ground source heat pumps are a low carbon heating option as they operate very efficiently.

 

What happens if we have another cold winter with lots of snow? Can the heat pump freeze?

Heat pump technology was designed in Sweden where very cold winters are the norm. Even when there is snow on the surface, the ground underneath still remains fairly constant. The liquid flowing around the system contains antifreeze and the pipes are well insulated to ensure that freezing does not occur.

Even in the depths of a British winter your ground source heat pump will continue to provide you with all the heating and hot water you need in your home.

 

Does the pump need a power source to run?

Yes it runs on electricity, but the efficiency output can normally achieve 3 or 4 times the efficiency of conventional electric heaters and immersion boilers.

 

I’ve heard that ground source heat pumps only work with underfloor heating. Is this true?

Oil and gas boilers normally heat water to a temperature of up to 75°C and the traditional radiator system is designed to run with these very high temperatures. It is, however, not necessary to run underfloor heating to such high temperatures as it works on the basis of a low temperature (about 35°C) over a large surface area. Ground source heat pumps can deliver low temperatures very efficiently. They can however, work to higher temperatures, but at the cost of decreased efficiency. We normally recommend first and foremost a comprehensive insulation plan which Altereco can help you with, teamed with oversized radiators or underfloor heating to optimise the benefit of the heat pump.

 

I don’t have a garden; can I still get a ground source heat pump?

A fair amount of outdoor space is required for a ground source heat pump in order to lay pipes underground. You may be better off investigating an air source heat pump.

I have a garden but it is quite small; can I still get a ground source heat pump?

It is possible to drill vertical boreholes for the ground loop 100m so this can be done for houses with small gardens, provided there is access for the drilling machinery.

 

I have a large garden but it is on a steep hill! Can I still get a ground source heat pump?

It is not necessary for the ground to be flat as long as the digging machinery can access your garden. Speak to our ground source heat pump specialists if you are unsure.

 

I currently heat my house with a gas boiler. Would a ground source heat pump save me money?

If other energy saving measures are taken along with the new technology and the technology is set to optimum efficiency, a ground source heat pump could save significant amounts of money on your bills. Good loft and wall insulation is essential to maximise the efficient output. The cost of installation is the main financial outlay but help is available with this through the Renewable Heat Incentive. At current prices gas is still competitively priced but as world supplies diminish the price is only set to rise in the future.

If saving money on energy is of importance and you want to talk to our experts then please call us on 08456 718 441. 

My house is old and draughty. Would a ground source heat pump actually keep me warm?

Heat pumps will work best when they are installed in a building with maximum provisions made for efficiency. This means that it is important to ensure that your building is well insulated and protected from drafts. If these pre-requisites are met, a heat pump could be the best way to keep your home warm and cosy.

 

I am building a new house. Would installing a ground source heat pump be a good idea?

Yes. You could save money on the installation costs of a heat pump if you have it installed at the same time as other works. This is because it is likely that many of the tools and machinery (diggers etc) would already be on site and it would be easy to custom build the house around the requirements of a heat pump. You also have the ability to insulate your new house to very high standard and perhaps even opt for underfloor heating which all complement the heat pump well. This will safeguard you against future increases in energy prices as well as ensuring that your house will meet current building regulations for minimal environmental impact.

Would getting a ground source heat pump make me eligible for the Renewable Heat Incentive?

 Yes. See our page on the Renewable Heat Incentive.

Get more details on Air source heat pumps

What is an air source heat pump?

Although you may have never come across an air source heat pump before, the principle behind the technology, heat transfer, is not a new one.  Rather than burning fuel to create heat, the device moves heat from one location to another. It actually works in the same way as a normal household refrigerator; which takes warmth from the food inside and transfers it to the air via a heat exchanger, thus cooling the contents.

An air source heat pump works the same way but in reverse, taking low grade heat from the outside air and bringing it inside. It is then linked up to heat the water in the central heating system and/or the hot water system.

How does cold air create warmth in my home?

Part of the process is to compress the air to increase its energy. Gas gets hot as it is compressed and expands as it cools. The low grade heat that comes into the heat pump is fed into a compressor thus raising it to a higher temperature. This can then heat the hot water and heating system.

How much space does an air source heat pump take up?

The total size of the equipment varies in size according to the size of the building it is serving. A normal domestic heat pump will not take up any more indoor space than a regular boiler with a buffer tank and hot water cylinder. The outdoor unit sits on an exterior wall and is a similar size to an air conditioning unit.

Can I run an air source heat pump with my existing oil boiler?

Yes, this is known as a bivalent system. It can be a good option so the air source heat pump is doing all the work at a high efficiency in warmer weather conditions, and the oil boiler is there as a back up for the very coldest times of the year. However, with oil prices sky rocketing, it may be better to upgrade sooner rather than later to a full sized air source heat pump that can cope on its own.

Will there be enough hot water from the air source heat pump for all of my family to have baths and showers?

We can design an air source heat pump system according to the needs of your household with varying sizes of hot water cylinders. The reheat time for the 200 litre hot water cylinder on the models which we supply is around 30 minutes which is very similar to that of a modern combi boiler.

Do I have to get underfloor heating for the air source heat pump to work efficiently?

It is not essential to team underfloor heating with air source heat pumps but they are technologies that are very well suited to each other. This is because the heat pump works best if it is required to deliver lower temperatures. It is much more efficient to run a lower temperature heat under the entire floor surface area than to heat small radiators up to very hot temperatures of 60°C or 70°C. If the air source heat pump is required to heat radiators in this way, its efficiency drops. Many people with air source heating find that it’s better to keep the system running on a low temperature almost constantly rather than heating the house intensively to a high temperature such as we are accustomed to with fossil fuel heating systems.

My house is old and drafty. Should I get an air source heat pump?

Before even considering a high efficiency heating system such as an air source heat pump, it is imperative to address the insulation and ventilation issues which your house may have. There is no point in running a low temperature heat through your home if it is all escaping through uninsulated walls or lofts. An air source heat pump could end up costing you more unless you deal with your energy losses! But thankfully, insulating is one of the simplest measures you can take to save money on your bills.