ABBE Level 3 Diploma in
Domestic Green Deal Advice
8. Renewables &
Microgeneration
Presented by
① Heat Pumps
⑥ Micro CHP
② Biomass & Biofuels
③ Solar Thermal
④ Solar PV
⑤ Wind Turbines
Domestic GDA Training – 8. Renewables & Microgeneration
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The Measures
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Renewable Energy
Renewable energy is energy which comes from natural resources,
naturally replenished. In its various forms, it derives directly from the
sun, wind, water or from heat generated deep within the earth.
Included is:
• Electricity and heat generated from solar
• Wind
• Ocean
• Hydropower
• Biomass
• Geothermal resources
• Biofuels
• Hydrogen derived from renewable resources
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Passive Solar Design
Passive solar design refers to the use of the sun’s energy for the
heating and cooling of living spaces. In this approach, the building itself
or some element of it takes advantage of natural energy characteristics
in materials and air, created by exposure to the sun.
• Passive systems are simple, have few moving parts, and require
minimal maintenance and require no mechanical systems.
• Passive design is practiced throughout the world and has been
shown to produce buildings with low energy costs, reduced
maintenance, and superior comfort.
Any design feature that maximises insulation and uses free solar gain
will be most cost effective in reducing the energy bills of a
building over its whole life span.
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Passive Solar Design
Recognising Passive Design
Passive solar design can be recognised by a range of features such as:
• Double or triple-glazed south-facing windows - which allow infrared
radiation to pass through - plus smaller north facing windows to minimise
heat loss
• Light tubes which channel sunlight from an outside roof or wall into a
room during the day
• Trombe walls – this is a natural design features which moves air warmed
by free solar heat into a space using convection
• A double-glazed conservatory or a solarium.
• In hotter months, conservatories can be shaded and naturally ventilated to
protect from excess heat and ultraviolet rays. By closing doors at sunset,
heat loss is prevented from the main building, using well insulated doors
or windows.
The need for dynamic simulation modelling put it
outside the scope of SAP.
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Heat Pumps - advice
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Air Source Heat Pumps
Air source heat pumps absorb heat from the
outside air. This heat can then be used to
heat radiators, underfloor heating systems,
or warm air convectors and hot water in your
home.
An air source heat pump extracts heat from
the outside air in the same way that a fridge
extracts heat from its inside. It can get heat
from the air even when the temperature is as
low as --15° C. Heat pumps have some
impact on the environment as they need
electricity to run, but the heat they extract
from the ground, air, or water is constantly
being renewed naturally
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Ground Source Heat Pumps
Ground source heat pumps use pipes which
are buried in the garden to extract heat from
the ground. This heat can then be used to
heat radiators, underfloor or warm air heating
systems and hot water in the home.
A ground source heat pump circulates a
mixture of water and antifreeze around a
loop of pipe - called a ground loop - which is
buried in the property’s garden. Heat from
the ground is absorbed into the fluid and
then passes through a heat exchanger into
the heat pump. The ground stays at a fairly
constant temperature under the surface, so
the heat pump can be used throughout the
year - even in the middle of winter.
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Heat Pumps
compressor
condenser
to the heating system
Horizontal Closed
Ground Loop
return from the
heating system
from energy source
Vertical Closed
Ground Loop
expansion valve
to energy source
Heat Pump system
Vertical Open Loop
Closed Pond Loop
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Changing to a Heat pump – air source
Do you have somewhere to put it? You'll need a place outside your home
where a unit can be fitted to a wall or placed on the ground. It will need plenty
of space around it to get a good flow of air. A sunny wall is ideal.
Is your home well insulated? Since air source heat pumps work best when
producing heat at a lower temperature than traditional boilers, it's essential that
your home is insulated and draught-proofed well for the heating system to be
effective.
What fuel will you be replacing? The system will pay for itself much more
quickly if it's replacing an electricity or coal heating system. Heat pumps may
not be the best option for homes using mains gas.
What type of heat emitter will you use? Air source heat pumps can perform
better with underfloor heating systems or warm air heating than with radiatorbased systems because of the lower water temperatures
required.
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Changing to a Heat pump – air source
Costs
Installing a typical system costs around £6,000 to £10,000. Running
costs will vary depending on a number of factors - including the size of
your home, and how well insulated it is, and what room temperatures
you are aiming to achieve.
Earnings
You may be able to receive payments for the heat you generate using a
heat pump through the government’s Renewable Heat Incentive (RHI).
This scheme should be launched in Summer 2013.
For systems installed after 1 August 2011, you may be able to get help
with the installation costs of a new air source heat pump through
the Renewable Heat Premium Payment scheme.
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Changing to a Heat pump
Considerations need to be given when
changing from a boiler to a heat pump.
Specialist calculations are required to
determine fabric heat losses and heat emitter
sizes.
Due to the lower flow temperature of heat
pumps compared to boilers, existing
radiators may be undersized.
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Changing to a Heat pump – air source
Existing system
Air source heat
pump performing at
220%
Air source heat
pump performing at
300%
Gas
£/year
CO2/year
-£130
-30kg
£110
850kg
Electric
£/year
CO2/year
£400
4,410kg
£650
5,230kg
oil
£/year
CO2/year
£50
830kg
£290
1,660kg
Solid
£/year
CO2/year
£50
4,610kg
£290
5,430kg
A negative number means it could cost you more to run the heat pump
than the system you are replacing
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Changing to a Heat pump – ground source
Is a ground source heat pump suitable
It doesn't have to be particularly big, but the ground needs to be
suitable for digging a trench or a borehole and accessible to digging
machinery.
Normally the loop is laid flat or coiled in trenches about two metres
deep, but if there is not enough space in your garden you can install a
vertical loop down into the ground to a depth of up to 100 metres for a
typical domestic home
Costs
Installing a typical system costs around £9,000 to £17,000. Running
costs will depend on a number of factors - including the size of your
home and how well insulated it is.
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Changing to a Heat pump – ground source
Existing system
Ground source heat
pump performing at
250%
Ground source heat
pump performing at
300%
Gas
£/year
CO2
-£20
400kg
£110
850kg
Electric
£/year
CO2
£510
4,780kg
£650
5,230kg
Oil
£/year
CO2
£160
1,200kg
£290
1,660kg
Solid
£/year
CO2
£160
4,980kg
£290
5,430kg
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Heat Pumps – overview
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Could lower your fuel bills, especially if you replace conventional
electric heating.
Could provide an income through the government’s Renewable Heat
Incentive (RHI).
Could lower the home’s carbon emissions, depending on which fuel is
being replaced.
Don't need fuel deliveries.
Can heat a home and provide hot water.
Need little maintenance - they're called ‘fit and forget’ technology.
Lower heat output than conventional system
High installation cost
Works better with an insulated dwelling
Need space externally to fit the unit
Performs best with underfloor heating due to lower water temperatures
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Biomass & Biofuels
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Biomass
Wood-fuelled heating systems, also called biomass systems, burn
wood to provide warmth in a single room or to power central heating
and hot water boilers.
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Solid Fuel
Biomass
•
Comes in various forms
• Wood logs
• Wood chips
• Wood pellets
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•
•
When biomass fuel is
combusted is releases carbon
dioxide, but no more than it
absorbs whilst the tree grows.
Biomass is therefore
considered to be carbon neutral
Wood pellets and wood chips
can be used in biomass boilers.
Wood logs are used in open
and closed room heaters.
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Costs
A pellet stove will cost around £4,300 including installation. Installing a
new log stove will usually cost less than half this, including a new flue
or chimney lining.
For boilers, an automatically fed pellet boiler for an average home costs
around £11,500 including installation, flue, fuel store and VAT at 5%.
Manually fed log boiler systems can be slightly cheaper.
Pellet costs depend mainly on the size and method of delivery. Buying
a few bags at a time makes them expensive. If you have room for a
large fuel store that will accept several tonnes of pellets at a time,
delivered in bulk by tanker, you can keep the cost down to around £190
per tonne in most parts of the UK.
Logs can be cheaper than pellets, but costs depend on the wood
suppliers in your local area, as they cost a lot to transport. If you have
room to store more than a year’s worth of logs you can save money by
buying unseasoned logs and letting them season for a year.
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Biomass & Biofuel Boilers
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Biomass
Advantages
• Affordable heating fuel ( price varies)
• low-carbon option ( considered carbon neutral)
• Financial support
• Variety in fuels ( logs, chips, pellets )
• Theoretically inexhaustible fuel source
Disadvantages
• Potential to run out of fuel
• Flue/chimney will need sweeping regularly
• Ash needs to be removed from the system periodically
• Expensive installation cost
• Storage of fuel is needed
• Still an expensive source, in terms of producing the biomass
• Not appropriate for all dwellings
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Biomass and Biofuel
Biomass is normally considered a carbon neutral fuel, as the
carbon dioxide emitted on burning has been (relatively) recently
absorbed from the atmosphere by photosynthesis and no fossil fuel is
involved.
The wood is seen as a by-product of other industries and the small
quantity of energy for drying, sawing, pelleting and delivery are
discounted.
Biomass from coppicing is likely to have some external energy inputs,
for fertiliser, cutting, drying etc. and these may need to be considered in
the future.
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Biomass
Fuel replaced
Expected saving
Expected carbon dioxide
saving
Electricity
£630 a year
7.5 tonnes a year
Oil
£270 a year
3.9 tonnes a year
LPG
£790 a year
3.6 tonnes a year
Coal
£270 a year
7.7 tonnes a year
Gas
£90 a year
3.1 tonnes a year
• Savings in carbon dioxide emissions are very significant - around 7.5
tonnes a year when a wood-fuelled boiler replaces a solid (coal) fired
system or electric storage heating.
• Financial savings are more variable.
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Solar Thermal
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Solar Thermal
What is solar thermal
technology?
Solar thermal systems heat water
using the energy from the sun,
which can then be stored for use
in domestic, public or commercial
buildings.
How does it work?
A closed circuit of pipes, powered
by a digitally controlled pump,
transports the heated transfer
fluid to a coil in the hot water
cylinder, which then stores the
heated water for later use.
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Solar Thermal
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Solar Thermal
Flat Plate Collectors
A flat-plate collector consists of an absorber, a transparent cover, a
frame, and insulation. Usually an iron-poor solar safety glass is used as
a transparent cover, as it transmits a great amount of the short-wave
light spectrum.
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Solar Thermal
Evacuated Tube collectors
In this type of vacuum collector, the
absorber strip is located in an
evacuated and pressure proof glass
tube. The heat transfer fluid flows
through the absorber directly in a Utube or in counter-current in a tube-intube system. Several single tubes,
serially interconnected, or tubes
connected to each other via manifold,
make up the solar collector. A heat
pipe collector incorporates a special
fluid which begins to vaporize even at
low temperatures. The steam rises in
the individual heat pipes and warms
up the carrier fluid in the main pipe by
means of a heat exchanger. The
condensed liquid then flows back into
the base of the heat pipe.
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Solar Thermal
Costs, savings and earnings
The cost of installing a typical solar water heating system is around
£4,800 (including VAT at 5%). Savings are moderate - the system could
provide most of your hot water in the summer, but much less during
colder weather.
Supplemented heating
Saving per annum
CO2 saving per annum
Gas
£60
230kg
Electric
£85
500kg
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Solar Thermal
Earnings
You may be able to receive payments for the heat you generate from a
solar water heating system through the government’s Renewable Heat
Incentive. This scheme should be launched in Summer 2013.
From August 2011, you may be able to get help with the installation
costs of a new solar water heating system through the Renewable Heat
Premium Payment scheme
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Solar Thermal – Installer Requirements
To get the most from a solar thermal system, just like solar PV, the
collector is best sited on a roof facing from east through west, with
south being optimal.
The roof structure would need to be in generally good condition( free
from defects) and the roof covering intact.
The system would need to be compatible with the existing heating
system and the solar thermal system sized appropriately to the heating
system and the occupants of the property
The system will need a thermal storage to enable the heat to be
exchanged. so combination boiler systems are not usually used in
conjunction with a solar thermal system.
Panels would usually fall under permitted development.
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Solar Thermal – Installer Requirements
Typical efficiencies for solar thermal will be around 60%, with the
majority of the hot water generated in summer.
Solar thermal panels even operate in low light conditions (cloudy days)
to good effect (1/3rd).
However in the UK you will always need an axillary heat source.
In installing solar thermal there would need to be a enough room for the
cylinder.
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Solar Thermal – Sizing
The general rule of thumb is half a solar thermal panel per person.
Various effects have a impact on the amount of heat the panels are
able to produce, e.g.:
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Orientation
Over shading
Pitch
Location in country
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Solar Thermal – Maintenance
Maintenance costs for solar water heating systems are generally
very low.
Most solar water heating systems come with a five-year or ten-year
warranty and require little maintenance.
In general you should keep an eye on your system to check that it is
doing what it has been designed to do.
You should have your system checked more thoroughly by an
accredited installer every 3-7 years to have the
• Pump checked; and
• Anti-freeze topped up.
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Solar PV
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Solar PV
Solar PV panels utilise the sun’s
energy and convert it into free,
renewable electricity that you can
use to power lighting systems and
appliances in your home.
PV produces electricity by
converting sunlight using the
photoelectric effect.
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Solar PV
Light (protons) literally ‘knocks’
electrons out of the semiconducting material.
Most PV is made from Silicon.
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Solar PV
This technology has been used since the late 50’s in the space industry
to power satellites and since the 70’s in solar powered calculators.
The first solar powered satellite, launched in 1958, is still in service.
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Solar PV
There are three types of silicon
cells:
1. Monocrystalline
2. Polycrystalline
3. Amorphous
There are also hybrid PV cells
combining a layer of amorphous
silicon over a layer of
monocrystalline (e.g. Sanyo).
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Solar PV – Monocrystalline Cells
Monocrystalline cells are cut from a single
crystal of silicon. Cylinders of silicon are
sawn into very thin slices called wafers, the
thickness of a human hair.
Due to the delicate and labour intensive
manufacturing process these cells are the
most expensive to make.
However, they are also the most efficient
with a range of 15% to 18%.
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Solar PV – Poly or Multicrystalline Cells
Poly or multicrystalline silicon
cells are cut from a block of
silicon that is made up of a large
number of crystals. The cells are
completely square unlike
monocrystalline cells.
Due to the impurities between the
crystals those cells are slightly
less efficient, having a range of
14% - 15%. However they are
cheaper to manufacture.
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Solar PV – Amorphous cells
Amorphous cells are
manufactured by placing a thick
film of amorphous (noncrystalline) silicon onto a wide
choice of surfaces. This is flexible
and can be mounted onto a
curved surface.
This is the cheapest form of
silicon cell but also the least
efficient at 6%-8%.
Although less efficient this type of
panel may be more efficient in
cloudy conditions, this is the type
of cell that is used in small
devices.
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Solar PV – Operation
First the inverter transforms the electricity generated by the panel from
direct current (DC) into alternative current (AC).
The electricity is then used as normal by the electrical appliances such
as lights, computers, fridges etc.
When the systems produces more electricity than needed the power is
sold back into the grid via an export meter.
However when the system doesn’t produce enough or no electricity (at
night for example), the electricity is imported from the National Grid as
normal.
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Solar PV – Optimum Conditions
Unlike solar thermal, PV is much more susceptible to variation in
performance based on light conditions, and the orientation and pitch of
the panels.
The 3 factors have an effect on the amount of energy that the system is
able to create.
Optimum conditions:
• South facing
• 30˚ pitch
• Unshaded
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Overshading
Overshading – extract from SAP
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Orientation and Pitch
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Overshading
Ideally no overshading should
occur.
As cells are normally connected in
string, a small amount of
overshading will affect the whole
panel or module.
The examples to the right show
partial shading that can reduce
the module efficiency by 50%.
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Solar PV – Costs
Costs
The average domestic solar PV system is 3.5 to 4kWp and costs
around £7,000 (including VAT at 5%), with the typical cost ranging from
£5,500 to £9,500.
Costs have fallen significantly over the last year. They vary between
installers and products, so we recommend getting quotes from at least
three installers
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Savings
A 3.5kWp system can generate around 3,000 kilowatt hours of
electricity a year – about three quarters of a typical household's
electricity needs. It will save over a tonne of carbon dioxide every year.
If your system is eligible for the Feed-In Tariff scheme it could generate
savings and income of around £645 a year (based on a 3.5kWp solar
PV system eligible for a generation tariff of 15.44p/kWh). You will get
paid for both the electricity you generate and use, and what you don't
use and export to the grid.
When applying for FITs you will need to show evidence of your
property's Energy Performance Certificate and this will affect what tariff
you can get.
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Wind Turbines
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Wind Turbines
The UK benefits from some of the highest average wind speeds in
Europe, making it an ideal candidate for wind energy.
The technology now generates around 2.5% of the UK’s electricity
and the proportion is increasing rapidly.
Between 2007 and 2009 the amount of electricity generated from wind
power in the UK increased by over 75% and in 2010 accounted for 58%
of all UK renewable electricity generation.
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Wind Turbines
There are two main designs of wind turbine –
those with a horizontal axis and those with a
vertical axis.
Most turbines for homes have a horizontal
axis whilst they can be mounted directly on a
building, turbines mounted on free-standing
towers or poles can be more effective at
capturing the wind’s energy.
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Wind Turbines
A typical 1kW building-mounted system costs approximately £2,000.
A typical 2.5kW pole mounted turbine costs approximately £15,000.
A typical 6 kW pole mounted system costs approximately £23,000.
Savings will depend on the turbine type size, local wind
conditions, economies of scale and the cost of the electricity
being replaced by using the wind turbine.
Rural or coastal dwellings can benefit more easily from wind
energy as local wind conditions are often good.
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Wind Turbines
Building mounted turbines are a new type of wind turbine designed
to be installed directly onto a building. This avoids the costs involved in
erected a freestanding tower and foundations. Designs of these
systems vary between manufacturers and include both vertical and
horizontal axis machines.
However, a building mounted turbine will not normally generate as
much electricity as an equivalent pole or tower mounted machine. It
may also add stress to your home’s building fabric due to increased
weight and vibrations.
You should always seek specialist guidance before installing a building
mounted turbine.
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Micro Combined Heat and Power (CHP)
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Micro-CHP
‘Micro-CHP’ stands for micro combined heat
and power.
Heat your home and generate electricity
at the same time with a micro-CHP unit.
This technology generates heat and
electricity simultaneously, from the same
energy source, in individual homes or
buildings. The main output of a micro-CHP
system is heat, with some electricity
generation, at a typical ratio of about 6:1 for
domestic appliances.
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Micro-CHP
A typical domestic system will generate up to
1kW of electricity once warmed up: the
amount of electricity generated over a year
depends on how long the system is able to
run. Any electricity generated and not used
can be sold back to the grid.
It typically costs between £5,000 - £6,000 to
have a Micro CHP boiler installed.
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Micro-CHP - Advantages
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Electricity generation as a by-product of heat. When the micro-CHP is
generating heat, the unit will also generate electricity to be used in your
home (or exported).
Carbon savings. By generating electricity on-site you could be saving
carbon dioxide compared with using grid electricity and a standard heating
boiler.
Financial income. Micro-CHP is eligible for Feed-in Tariffs and you will
earn 11.0p for each kWh of electricity generated by your system. You will
also receive 3.2p for each kWh of electricity you export.
Easy installation. For the householder, there is very little difference
between a micro-CHP installation and a standard boiler. They are roughly
the same size. However, the installer must be approved under the
Microgeneration Certification Scheme.
Servicing costs and maintenance are estimated to be
similar to a standard boiler – although a specialist will
be required.
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Micro-CHP – Disadvantages
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Micro CHP is a relatively unproven technology.
Carbon savings in most smaller, newer domestic properties are insignificant.
Micro CHP is inefficient for short run cycles.
There is a high incidence of unreliability in currently installed units.
On average, 50% of electricity generated in domestic applications is
surplus. There is a current shortfall of available export reward tariffs for
excess electricity directed to the grid.
Current life expectancy of micro-CHP units is reported to be relatively low.
High installation costs.
Some CHP units are heavy – requiring solid flooring.
Current payback period is in excess of 20 years, but will reduce
along with increased production.
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Questions?
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Web Links
www.stroma.com/certification
Contacts
Stroma Certification Ltd.
4 Pioneer Way, Castleford, WF10 5QU
0845 621 11 11
[email protected]
Domestic GDA Training – 8. Renewables & Microgeneration
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