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Grid Connections for Solar PV Systems and Elecricity Storage Systems in the UK - Engineering Recommendation G98

Updated February 2020: If your solar PV or electrical storage system is to be connected to the National Grid, is to run in parallel with the grid, will shutdown during a powercut and is under 16A per phase (3.68kWp AC single phase, 11.04kWp AC three phase), then this is a most likely a Micro-Generator. Grid connections for Micro-Generators are carried out in accordance with Engineering Recommendation G98.

The key stakeholders involved with connecting a Micro-Generator to the National Grid under G98 are 1) The Distribution Network Operator (DNO) 2) The Owner of The Micro-Generator 3) The Installer 4) The Grid Connection Equipment Manufacturer 5) The Energy Networks Association (ENA) 6) The National Grid.

G98 is a simple connection procedure for Fully Type Tested systems under 16A per phase, systems are installed on an install and inform basis. If the Micro-Generator to be connected is installed in compliance with G98. The DNO can be notified of the installation under G98, up to 28 days after the commissioning date.

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Solar PV Mains Connection The National Grid - What is the National Grid? The National Grid is owned by a company called National Grid PLC. Their high voltage electricity transmission network is made up of power lines, gas pipelines, storage facilities and interconnectors. Connecting power stations, large substations and very high power users across the UK. The National Grid delivers power at high voltage over distance to where is is needed. The primary receipients from the Transmission Network are the Distribution Network Operators (DNOs) who will usually distribute power via low voltage (230/400V) Alternating Current (AC), to households, businesses and industrial users.
Ground Mounted Commercial Solar PV Panel Mounting System

Electric Car Outside Solar House

Distribution Network Operators (DNOs) DNOs deliver electrical power to consumers including homes and businesses via power distribution networks that the DNOs own and operate. If you would like to connect your Micro-Generator to the National Grid and run your Micro-Generator in parallel and export into the National Grid, then you firstly need to connect your system to the power distribution network of your local DNO under Engineering Recommendation G98.

The document that outlines how these connections are made, managed and documented is Engineering Recommendation G98, updated 16th June 2019. A List of DNO's Updated April 2019, a copy of Engineering Recommendation G98 and a Guide to Engineering Recommendation G98 are also available to download below:

NB: Due to competition in the power supply market, DNOs may not neccessarily be the same companies that bill you for the power that you use or the organisation that agrees to purchase the power that you generate. DNOs are responsible for keeping the underlying power networks running. A G98 connection agreement with a DNO only covers the physical and technical details of the connection. Seperate arrangements will need to be made for the buying and selling of electrical power.

Commercial Flat Roof Solar PV Panel Installation Connection Agreement under Engineering Recomendation G98 The Micro-Generator must fulfil the criteria below to connect under Engineering Recommendation G98:
  • A Fully Type Tested Micro-Generator has been installed with a Verification Report supplied to the DNO
  • Rated Output: Under 16A Per Phase for connection at Low Voltage
  • Grid Interface Protection - Installed to local standards and functionally tested
  • System will Shutdown during a power outage
  • Isolation Switch installed, capable of isolating all phases and Neutral, Lockable in the 'Off' position
  • Circuit diagram displayed on-site, Grid interface Protection Settings displayed on-site
  • Equipment conforms to all European Directives and is labelled with a CE marking

DNO to be notified of the G98 Grid Connection and provided with all of the paperwork confirming the above within 28 days of commissioning

Roof Mounted Solar PV Panel Installation Type Test Register The type test register is a database hosted by the Energy Networks Association (ENA) where manufacturers of grid connection products such as solar inverters, mains relays and battery storage systems can register their products as meeting the requiremens of G98, G99 and or G100. NB: The ENA does not test or validate the test results provided by the manufacturers. System Owners need to satisfy themselves that generation equipment that is installed has been tested and certified to be compliant with Engneering Recomendations G98, G99 or G100.
Solar Barn Parallel Operation Power generation systems that run alongside the grid such as grid-tied solar PV systems, are said to run in parallel with the National Grid i.e. they feed into, take supply from, synchronise and work with the grid to provide power to users. For worker safety, grid-tied systems will shut themselves down in the event of grid failure. In most cases solar power systems will automatically restart, synchronise with and connect to the grid once the grid situation is stable.

If your system is an electrical storage system that will also be used during a power cut, is over 16A per phase, hasn't been type tested as a complete system and or doesn't fit in with G98 for another reason than an application will need to be made and the connection made under Engineering Recommendation G99.

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Mains/Grid Isolation and Surge Protection

Mains/AC Surge Protection Solar PV Systems

A whole house surge protector is installed to provide protection from transient overvoltages originating from the mains/grid. A whole house surge protector is installed directly inline and as close as possible to the incoming mains/grid supply meter, this allows for surge protection for all circuits and equipment including solar inverters, routers, stereos and other sensitive electrical equipment within the network. The addition of a 100Amp lockable isolator also allows for safe and convenient isolation of all electrical equipment within the network including consumer units, solar inverters, battery storage units and EV chargers from the mains/grid in one place.

Surge protectors are in compliance with the recently updated 18th edition amendment 2 of BS7671.

Mains/Grid Isolation and Surge Protection


Solar PV Surge Protection (DC Surge Protection)

DC Surge Protection Solar PV Systems

DC surge protection devices (SPDs) are installed between the solar panels and the solar inverter to protect both the solar inverter and the downstream electrical equipment from transient overvoltages of an atmospheric origin impacting the electrical system via the DC side of the system / the solar panels.

DC Surge protectors are in compliance with the recently updated 18th edition amendment 2 of BS7671.

Solar PV Surge Protection (DC Surge Protection)

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Articles: Further Information, Calculators & Solar Inverter Fault Codes

Lots of articles, calculators and technical information including links for further reading. Covering a range of topics related to the installation and maintenance of solar photovoltaic and electrical systems in the UK.

/Solar PV Information Articles

How to provide power to a house using a portable generator

In this article we show you how to power your home using a portable diesel, petrol or LPG generator. We look at changeover switches, the importance of earthing, generator loadings, how to isolate non essential loads. We ask where to locate the generator when it's in operation, how best to safely isolate the grid/mains power supply and switch to a generator supply.

Solar PV, Safety & The Building Regulations

Residential PV systems notifiable under Part P. Special consideration needed for Part A. A combination of serious risks for solar PV installers.

Ground Faults, Isolation (ISO) Faults, RISO Low Faults and Insulation Resistance Faults with Solar PV Systems

After a number of years exposed to wind, rain, snow, ice and sometimes animals; solar panel systems can start to develop faults. The most common faults we find related to exposure are ground faults, isolation (ISO) faults, RISO low faults and insulation resistance faults. In this article we take a look at what these faults are, the possible causes and what steps are taken to identify and resolve them.

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We are located in Wanborough, very close to Swindon in Wiltshire, Southern England, UK. From here we service clients within a 90 minute driving radius including the towns, cities and regions below:

Swindon: Abingdon, Aldbourne, Amesbury, Andover, Banbury, Basingstoke, Bath, Berkshire, Bicester, Blunsdon, Box, Bracknell, Bradford on Avon, Bridgwater, Bristol, Buckingham, Burford, Burnham on Sea, Calne, Camberley, Cardiff, Carterton, Cheltenham, Chippenham, Chipping Norton, Chipping Sodbury, Cirencester, Corsham, Cricklade, Devizes, Didcot, Evesham, Eynsham, Faringdon, Frome, Fleet, Glastonbury, Gloucester, Gloucestershire, Hampshire, Henley-on-Thames, Highclere, Highworth, Hook, Hungerford, Keynsham, Kingsclere, Lambourn, Lechlade, Ledbury, Ludgershall, Lyneham, Maidenhead, Malmesbury, Marlborough, Marshfield, Melksham, Minety, Newbury, Newport, Oxford, Oxfordshire, Pewsey, Purton, Ramsbury, Reading, Ross on Wye, Royal Wootton Bassett, Salisbury, Shaftesbury, Shalbourne, Slough, Southampton, Stow, Stratford upon Avon, Stroud, Swindon, Tewkesbury, Thatcham, Tidworth, Trowbridge, Wanborough, Wantage, Warminster, Weston Super Mare, Wiltshire, Winchester, Windsor, Witney, Wokingham, Worcester, Wroughton and Yate.

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