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Page 1 Connecting a microgeneration system to a domestic or similar electrical

Page 1 Connecting a microgeneration system to a domestic or similar electrical installation (in parallel with the mains supply) Best Pracce Guide 3 (Issue 3) In electronic format, this Guide is intended to be made available free of charge to all interested parties. Further copies may be downloaded from the websites of some of the contributing organisations. The version of this Guide on the Electrical Safety First website (www.electricalsafetyfirst.org.uk) will always be the latest. Feedback on any of the Best Practice Guides is always welcome – email bpg@electricalsafetyfirst.org.uk Electrical Safety First is supported by all sectors of the electrical industry, approvals and research bodies, consumer interest organisations, the electrical distribution industry, professional institutes and institutions, regulatory bodies, trade and industry associations and federations, trade unions, and local and central government. *Electrical Safety First (formerly the National Inspection Council for Electrical Installation Contracting) is a charitable non-profit making organisation set up in 1956 to protect users of electricity against the hazards of unsafe and unsound electrical installations. Published by: Electrical Safety First Unit 331 Metal Box Factory 30 Great Guildford Street London SE1 0HS Tel: 0203 463 5100 Email: bpg@electricalsafetyfirst.org.uk Website: www.electricalsafetyfirst.org.uk Electrical Safety First and other contributors believe that the guidance and information contained in this Best Practice Guide is correct, but all parties must rely on their own skill and judgement when making use of it. Neither Electrical Safety First nor any contributor assumes any liability to anyone for any loss or damage caused by any error or omission in this Guide, whether such error or omission is the result of negligence or any other cause. Where reference is made to legislation, it is not to be considered as legal advice. Any and all such liability is disclaimed. © Electrical Safety Council. November 2015 Best Practice Guide Electrical Safety First is indebted to the following organisations for their contribution and/or support to the development of this Guide: BEAMA www.beama.org.uk British Gas www.britishgas.co.uk Certsure www.certsure.com City & Guilds www.cityandguilds.com ECA www.eca.co.uk ENA www.energynetworks.org HSE www.hse.gov.uk Institution of Engineering and Technology www.theiet.org NAPIT www.napit.org.uk SELECT www.select.org.uk SPACES www.thespaces.org.uk Sundog Energy www.sundog-energy.co.uk Several of the photographs in this Guide have been extracted from a superseded Electrical Safety First DVD, courtesy of Navigator Productions Ltd. Others were kindly supplied by Nick Blakeley Electrical and Bradford Metropolitan District Council. This is one of a series of Best Practice Guides produced by Electrical Safety First* in association with leading industry bodies for the benefit of electrical contractors and installers, and their customers. Page 3 Connecting a microgeneration system to a domestic or similar electrical installation (in parallel with the mains supply) The aims of this Guide are: • to provide an overview of microgeneration intended to produce electrical energy, otherwise known as small-scale embedded generation (SSEG), • to provide information on the legal and contractual issues relating specifically to the installation of microgenerators with electrical rating up to 16 A per phase (including the relationship of the consumer with the electricity supplier and the distribution network operator (DNO)), and • to give guidance on the particular electrical issues, including electrical safety issues, that arise when installing or connecting a microgenerator. Photo courtesy of Sundog Energy Ltd Page 4 The Guide does not provide installation guidance specific to any particular types of microgeneration. Section 712 of BS 7671 contains particular requirements for photovoltaic installations, as does the Code of Practice for Grid Protected Solar Photovoltaic Systems published by the Institution of Engineering and Technology in 2015. For any microgenerator installation, the instructions of the manufacturer or supplier should be followed. The Guide does not provide installation guidance where it is intended to install more than one microgenerator. In such cases it is necessary to consider the possibility of interaction between the protection and control equipment of the microgenerators, and the specific advice of the manufacturers or suppliers of each of the microgenerators should be obtained and followed. Where multiple microgeneration installations are to be installed in a close geographical region (such as in a housing development), it is also necessary to obtain the permission of the Distribution Network Operator (DNO) in advance. Guidance on getting a generation scheme connected to the distribution network can be found in the DG Connection Guides published by the Energy Networks Association (ENA). These may be downloaded from: www.energynetworks.org/electricity/ engineering/distributed-generation/ dg-connection-guides.html The Guide does not cover Feed-in Tariffs. On 1 April 2010 the Government launched Feed-in Tariffs (FITs), which are payments to microgenerators based on both what they generate, and what they export to the grid if they choose to do so. More information on FITs is available from www.energysavingtrust.org.uk To be FIT-eligible, electricity-led microgenerator installations with a Declared Net Capacity of 50 kW or less must conform to the Microgeneration Certification Scheme (MCS). Other schemes may in future be approved as being equivalent. For an installation to be MCS compliant both the equipment being used and the installation company must have been certificated by a UKAS accredited Certification Body. Much of the equipment used in an installation will have been tested against MCS performance, quality and safety standards before being certified. (Details of MCS standards are available on their website.) For an installation company to become certificated, a Certification Body will assess its technical competence, as well as checking that it has appropriate business processes (such as quality standards, complaints handling procedures etc). In order to become MCS certified, installation companies must be members of the Renewable Energy Consumer Code (or an equivalent). More information on becoming an MCS installer, and on what equipment is currently approved under the scheme, is available from www.microgenerationcertification.org Photo courtesy of Sundog Energy Ltd Photo courtesy of Sundog Energy Ltd Page 5 Introduction The UK Government is committed to encourage the wider use of renewable energy generation, and to technologies such as combined heat and power (CHP) that offer improved efficiency compared to traditional bulk generation in large power stations. This commitment reflects undertakings made with the UK’s partners in the European Union and internationally to reduce greenhouse gas emissions and reliance on fossil fuels. Generation of electricity closer to the point of use avoids some of the losses that arise in the transmission and distribution of electricity to consumers. This currently amounts to up to 10% of units dispatched. Even for the most modern combined cycle gas generating stations with production efficiencies of 50-60%, the efficiency from the point of generation up to the point of use in a consumer’s installation is generally well below 50%. Decentralised generation, if sufficiently widely adopted, could also improve the reliability and resilience of the electricity supply system, though this clearly depends on the types and relative amounts of generation that are installed. For example, photovoltaic systems do not generate at night, and wind power does not function at very low or very high wind speeds. Over the past few years, considerable attention has been given to the development of microgenerators that are intended to be installed in domestic and similar premises. Such microgenerators are rated at up to 16 A per phase. At a nominal voltage to Earth (U0) of 230 V, this corresponds to 3.68 kW on a single phase-supply or 11.04 kW on a three-phase supply. A range of technologies have been developed to take account of the rather different technical and operational challenges that the domestic environment presents compared to more traditional small generator designs. Not least of these is the importance of providing simple, safe and reliable products at a price that is in proportion to the consumer’s reduction in electricity purchase costs, so offering an attractive payback. Photo courtesy of Evoko Energy Ltd Page 6 Types of generation It is, of course, possible to install and operate a generator and installation completely independently of the normal mains supply and to run certain appliances entirely on this separate system. This Guide, however, considers only generators that are intended to work in parallel with low voltage distribution systems, as this represents the most practical approach for most consumers. The assumption is that consumers generally will wish to continue to use electricity as and when required at the throw of a switch, without needing to be aware as to whether the generator is working or not. Currently, the options can be divided into two broad classes from the point of view of connection into an existing installation: • Renewable sources of electricity, powered by wind, light or hydro-power, or fuel cells. Many of these generate direct current (d.c.) and are connected to the mains through a d.c. to a.c. inverter • Gas, oil and biomass fired micro-cogeneration (combined heat and power (CHP)) systems. The primary function of these systems is to provide for heating and hot water needs, in place of a traditional boiler or water heater. However, they include a small generator that provides electricity, powered by some of the heat energy produced for the water heating process. This Guide does not give guidance on the heat production aspects of microgenerators. Renewable sources uploads/s3/ best-practice-guide-3.pdf