The Greenhouse Trust

(The glass/photovoltaic (PV) roof over the courtyard garden at the Greenhouse. This solar array converts daylight into electricity with no carbon emissions. The brighter the sunlight the more electricity is generated.

PHOTOVOLTAIC (PV)

Climate change is now the greatest challenge facing humanity today. During the coming decades, we must significantly reduce the energy we waste and the CO₂ generated. Historically electricity and space heating have been provided by burning fossil and nonrenewable sources (oil, coal, gas and uranium), these all generate carbon dioxide (CO₂) emissions: the main cause of climate change.

HOW IT WORKS

Unless we dramatically redesign our homes and rethink the way we use energy, we’re on track for a climate that humans are unlikely to be able to survive in.

Sun/daylight hits the photovoltaic cells and is converted into electricity. An inverter close to the solar panels converts the electricity for use in the building. When the solar energy system produces more electricity than is needed it is exported to the grid. When there is no day/sunlight, electricity is imported from the grid in the conventional way.

“Warming of the planet’s climate system is unequivocal as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level.”
Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report 2007

“It’s becoming dire, because we have to start within the next few years on a different track. We have to realise that we have to get to energy sources beyond fossil fuels, and we need to do that sooner.”
James Hansen, NASA

INSULATION, INSULATION, INSULATION

A timber & cork lining has been added to the inside of the Greenhouse to improve the insulation value of these former (Victorian) houses.

“If every house in the UK was insulated to the highest standard and fitted with solar powered generation, a 60% carbon emissions reductions target could be achieved.”
A 2004 study by the University of Oxford

DESIGNING IN ONSITE MICROGENERATION

PV electricity generated close to the point of use maximises both the efficiency of the electricity generated and reduces the demand on the transmission network. Both mean a reduction in the use of fossil fuels. (Image by Steve Miilner, Zed Factory, www.zedfactory.com)

 

“It is irresponsible not to plan new communities around onsite renewable energy generation. It is also fraudulent to pass off low-embodied carbon construction as a valid green building solution without integrated microgeneration.“

“It is the adoption of contemporary patterns of energy and resource consumption within historic building fabric that fuels much of our international aggression for oil reserves. Even if the entire existing building stock achieved a 70% reduction in energy demand through radical energy-efficient renovation, it would use up the entire stock of available national communal energy reserve even at the more optimistic 2050 levels.”
Bill Dunster – Architect Bed Zed
www.zedfactory.com

 

PV SOLAR ELECTRICITY – LOCAL DECENTRALISED ENERGY

Homes and workplaces need to become mini-power stations, collectively generating a significant amount of electricity and helping to reduce the level of CO2 being generated. The current outdated electricity system is so inefficient that two-thirds of the energy generated by burning fossil fuel is wasted before it even gets to us.

As well as generating electricity the PV’s provide shade for the garden and increase the volume of rainwater collected (used for flushing the public toilets here).

This huge loss occurs because large power stations waste heat when burning fossil fuels and even more energy is lost transporting electricity along power lines across relatively long distances.

“Energy transportation charges make up about one fifth of a household customer’s bill.” Ofgem 2007

A local (decentralised) energy system means that houses can become mini power stations. Electricity generated can be used directly by the owners of the house or workplace, and the surplus can be fed into the local network. At this level of efficiency and with a local network hosting renewable energy from numerous suppliers, security of supply and global warming emissions (created by power generation) could be reduced by at least 50%. If applied across the UK, a decentralised system would reduce overall CO2 by at least 15%.

Already in the UK, Woking Borough Council has slashed its emissions of CO2 by almost 80%. And Holland meets 40% of national electricity demand through decentralised (local) energy.

Significantly higher standards of building design and the addition of PV to new and old buildings have the potential to generate a new green industrial age.

TERMS USED Kilowatt hour (kWh): 1 kWh is the same as 1 unit on your electricity bill, and is enough power to light a 100W light bulb for 10 hours (or 50 hours for a typical 20W low-energy light bulb) Kilowatt peak (kWp): This is used to convey the peak output

ENVIRONMENTAL (CO2) SAVINGS A small sized (1kWp) system saves approximately 0.455 tonne (455kg) of CO2 per year. The energy used to create the solar technology requires approximately 2-3 years of CO2 payback time.

The PV array on the front was installed in September 1999 and has a maximum capacity of 0.85 kWp.

THE GREENHOUSE HAS TWO SOLAR ELECTRICITY (PV) INSTALLATIONS

The price for PV is determined by numerous factors such as the type of silicon used, the location of the array and the positioning of the technology. To make full use of the solar panels they should ideally be south facing and tilted at an angle of 30 degrees to the horizontal. To generate more energy in the winter a more upright angle is required (the sun is lower during the winter months).

THE PV ARRAY ON THE FRONT

The PV array and electrical supply system on the front of the Greenhouse cost £7,100 (in 1999) and 7 m². Since 1999 the price of electricity has continued to rise above the basic level of inflation. Everyone agrees that the economic costs of extracting fossil fuels will increase, and the environmental impact of burning fossil fuels will become ever more visible as climate change shapes our lives.

For approximately 6 months of each year – April to September (varies according to the level of sunlight) the system is capable of generating in the region of 0.5 – 2.0 kWh per day. The meter reading for the year June 2008- June 2009 was 630 kWh. The price the Greenhouse receives for electricity generated on site has risen from 5p per kWh to 15p per kWh. Good Energy currently award the Greenhouse 15p per kWh generated (under the current ROCs scheme), which is deducted by Good Energy from the electricity bill.

Calculated on 630 kWh x an average of 8p over the ten years, this means that the system has paid back £504. At this rate it would take 140 years to cover the investment costs! However, even this tiny system has reduced the Greenhouse’s CO₂ footprint by 3 tonnes over the decade.

The array in the garden was installed in October 2006 and has a maximum capacity of 2.5 kWp. The area of the panels is 20m2.

The smallest system size usually installed on a domestic property is 1-kilowatt peak (kWp). In the UK, a 1 kWp system is expected to produce at least 750 electrical kWh - every year. The average household in the UK currently uses approximately 4,000 kWh every year. Therefore a 4 kWp system will generate enough electricity for an average household, with potential to export a small amount of electricity to the grid.

THE GARDEN PV ARRAY

For approximately 6 months of each year – April to September (varies according to the level of sunlight) the system is capable of generating in the region of 8-10 kWh per day. On very bright/high summer days, an output of 15 kWh has been obtained. The total electricity generation since installation of the combined systems is 3,850 kWh. The array over the courtyard garden cost £24,000 in 2006 (with a 50% government grant). It estimated that the system has recovered

£462.00 of the investment (calculated on 3,850 kWh @ 12p to reflect an average price during the three years of operation) and reduced the building’s CO2 footprint by 2.01 tonnes (2,010 Kg) – (calculated 0.67 tonnes - 670 kg per year).

 

 

The PV panels over the garden were installed to publicly demonstrate the technology where they could be easily viewed and the benefits discussed by visitors.

THE GREENHOUSE EXPORTS ELECTRICITY

In the summer months the system provided sufficient electricity to run all the equipment in the Greenhouse when we are closed (Sundays and Mondays). During this time the building is running for free! To date the total electricity exported is 1,950 kWh (see the section on Feed in Tariffs).

THE SITE LIMITATIONS OF THE GREENHOUSE SYSTEM

The Sun’s apparent height in the sky changes from winter to summer. This yearly north to south solar motion is called solar declination. The PV panels at the back (north side) of the building highlight the issue of shading and shadowing which particularly in winter impacts on the amount of electricity generated. The daily east to west solar motion is called solar azimuth. If the PV module is perpendicular to the Sun at solar noon, it is not even close to perpendicular in the morning and evening.

PLANNING ISSUES

Solar PV panels are, and should be installed on as many building as possible. It is estimated that up to 50% of the properties in Norwich/Norfolk, along with the rest of the UK, could benefit from solar technology.

Central America, India, China, Europe, all around the world vital communication systems and key aspects of modern living can be added to homes. What we do, or don’t do to end the use of fossil fuels in the rich world is, and will impact the poorest on the planet.

"It is patently absurd that you should be able to put a satellite dish up on your house but should have to wrestle with the planning process for small scale microgeneration which is no more obtrusive. We want far more microgeneration to be treated as permitted development." Yvette Cooper, Minister for Housing and Planning, 2006

"We need to seize on new development as an opportunity, not a threat. It is time to rethink the way we build. It is time to rethink the way we design our homes and communities, if we are to build communities for the future that are truly sustainable.”
Yvette Cooper, Minister for Housing and Planning, 2006

 

CURRENT UK PLANNING GUIDANCE STATES THAT Solar PV (and solar thermal) (stand-alone) are permitted unless: More than 4 metres in height Installed less than 5 metres away from any boundary Above a maximum area of array of 9m2 Situated within any part of the curtilage of the dwelling house or would be visible from the highway in Conservation Areas and World Heritage Sites. Solar PV (roof mounted) are permitted unless; Panels when installed protrude more then 200mm They would be placed on the principal elevation facing onto or visible from the highway in buildings in Conservation Areas and World Heritage Sites. National planning legislation remains very weak, and it is likely that you will need the support of your elected councillors to install PV technology and micro-renewables anywhere other than hidden from view on existing properties. However, the PV panels on the front of the Greenhouse (The Greenhouse is a II* listed building) demonstrate that elected council members can counter the inertia of the planning system and the lack of support and opposition created by local planning/conservation officers.

“Some of the materials are modern, and the physics logic generating the building form will inevitably change traditional aesthetics. This process could be considered as a celebration and an evolution of a new 21st-century vernacular that will absorb elements of tradition, but ultimately produce a recognisable architectural language expressing optimism for a future that works without waste and pollution.”
Bill Dunster – Bed Zed Architect

“If an architect proposes to hide solar panels behind a parapet invisible from the street, or formal stylistic concerns start to create poor solar access, poor daylight and overshadowing or windshade, the energy-generation problems are automatically sent offsite to centralised fossil fuel power stations.”
Bill Dunster –Bed Zed Architect

Before considering PV technology it is important to maximise the energy efficiency standard of your building as much as possible. All grant schemes require you to demonstrate that you have done this before applying. SOLAR CHECKLIST Insulated the whole of the loft of the property to meet current building regulations e.g. 270mm of mineral wool loft insulation or suitable alternative Installed cavity wall insulation (if applicable) Fitted low energy light bulbs in all light fittings Installed basic controls for your heating system to include a room thermostat and clock/timer Installed all practical energy saving measures to electrical equipment in the house Studied a whole year’s bill to see how much energy you use and see how much you can save Worked out how much electricity you use and calculated the area of PV technology you require Take photos, or draw diagrams of your roof to check you have enough roof space and to check that the roof is not affected by shade at any time of day Take photos, or draw diagrams which demonstrate that the roof is capable of taking the weight of the panels

OFF GRID

PV can be used to generate ‘off grid’ (not part of any electricity transmission network). However, ‘off grid’ generation requires the use of batteries (to store the electricity), which is less efficient, and the materials used in the construction of batteries raise separate environmental issues. Generally this isn’t a sensible option for urban living.

FEED IN TARIFFS (FITS)

The German government led the way by introducing FITS. To date seventeen European countries have adopted a feed-in tariff system with considerable success. FITS work by guaranteeing long-term premium payments for electricity generated from renewable sources, fed into the grid. Using FITS, the Government fix the level of the tariff to be paid for each renewable technology and set the length of contract. FITs have been shown to be the most cost effective support method, placing a legal obligation on utilities to purchase electricity from renewable energy installations.

See the feed-in tariff information here

USEFUL CONTACTS

For every new customer who signs up to Good Energy via our website, the Greenhouse will receive £40. By being part of a local (decentralised) energy network the Greenhouse is helping to further reduce the overall consumption of fossil fuels being burnt which add to global warming

Good Energy
Monkton Reach
Monkton Hill
Chippenham
Wiltshire
SN15 1EE
Tel: 01249 766090 Fax: 01249 766091
Email: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
www.goodenergy.co.uk

 

GREENHOUSE INSTALLATIONS WERE CARRIED OUT BY

The Department of Energy & Climate Change operate the Low Carbon Building’s Programme, which provides grants. The information can be found via Sundog’s website or direct at: www.lowcarbonbuildings.org.uk

Sundog Energy Ltd.,
Matterdale End
Penrith
Cumbria
CA11 0LF
Tel: 017684 82282
Fax: 017684 82600
www.sundog-energy.co.uk

C21e - Roofing tiles that integrate existing materials. Photo by Solarcentury

 

Solarcentury
91-94 Lower Marsh
Waterloo
London SE1 7AB
www.solarcentury.co.uk

 

 

 

 

 

Designed by: Anya Temple www.anyatemple.com
Printed by: Modern Press
10 Santareen Road, Long Stratton
Tel: 01508 531899

PDF Avaliable to Download (4.4MB)

Published by: The Greenhouse Trust
42-46 Bethel Street, Norwich, NR2 1NR
Charity Number: 1037992
www.GreenhouseTrust.co.uk
August 2009

Sponsored by: NatureSave and The Helen Roll Charity

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