| B9 Solar Ltd | Larne | 2025 |
| B9 Technologies Ltd | London | 2022 |
| Babeleigh CE Turbine Limited | Wadebridge | 2012 |
| Backhill of Culbirnie [2016] Ltd | Turriff | 2016 |
| Backup Energy Ltd | Warrington | 2022 |
| Badachro Hydro Limited | Little Dunkeld | 2015 |
| Baglan Operations Limited | London | 1999 |
| Baglan Pipeline Limited | London | 1999 |
| Baglan Solar Limited | London | 2020 |
| Bagley Biogas (Trading) | Ellesmere | 2014 |
| Bagley Biogas Ltd | Ellesmere | 2013 |
| Bagmoor Holdings Limited | London | 2012 |
| Bagmoor Wind Limited | London | 2004 |
| Bagnall Energy Limited | London | 2013 |
| Baham Solar Ltd | Bristol | 2020 |
| Bailey Airconditioning Ltd | Deal | 2018 |
| Bailey Renewables Limited | Llanbedr | 2011 |
| Bailey Solar Limited | London | 2016 |
| Baileys Utilities and Training Ltd | Telford | 2024 |
| Baillie Windfarm Limited | Glasgow | 2003 |
| Bain Energy Limited | Lincoln | 2022 |
| Bake Farm Solar Park Limited | London | 2013 |
| Baker Green Energy Limited | London | 2022 |
| Baker Street Generation Limited | Greenock | 2018 |
| Balagowan Hydro Limited | Edinburgh | 2014 |
| Balance Solutions 1 Ltd | St. Helens | 2022 |
| Balbougie Energy Centre II Limited | Northampton | 2021 |
| Balcas Bioenergy Limited | Enniskillen | 1993 |
| Balcas SPV NO.2 Limited | Edinburgh | 2013 |
| Balcombe Solar Limited | Hove | 2015 |
| Baldowrie Renewables Limited | Perth | 2011 |
| Baleney Renewables Limited | Belfast | 2012 |
| Balhaldie Energy Limited | Dunblane | 2012 |
| Balhearty Solar Limited | Edinburgh | 2016 |
| Balin Solar Farm Limited | Stockport | 2022 |
| Balintombuie Hydro Ltd | Inverness | 2015 |
| Ball Green Energy Storage Limited | Reading | 2024 |
| Balliemeanoch Hydro Limited | Edinburgh | 2013 |
| Balliemeanoch Renewables Limited | Forfar | 2023 |
| Balliemeanoch Wind Farm Limited | London | 2012 |
| Ballimore Hydro Limited | Lochearnhead | 2011 |
| Ballingham Court Limited | Hereford | 2015 |
| Ballinloan Renewables Ltd. | Perth | 2011 |
| Balls Wood Solar Limited | London | 2014 |
| Ballyatwood Wind Ltd | Ballywalter | 2015 |
| Ballycolin Wind Ltd | Cookstown | 2012 |
| Ballycrum Hydro Limited | Londonderry | 2012 |
| Ballydoolagh Enterprises Limited | Enniskillen | 2015 |
| Ballydugan Wind Limited | Belfast | 2016 |
| Ballygarvey Solar Ltd | London | 2014 |
| Ballykeel Wind Farm Limited | Belfast | 2013 |
| Ballykenny Solar Limited | Tiverton | 2018 |
| Ballykilbeg Wind Ltd | Cookstown | 2014 |
| Ballyleagry Solar Farm Limited | Lisburn | 2025 |
| Ballylig Wind Ltd | Cookstown | 2016 |
| Ballymacbrennan Ltd | Lisburn | 2008 |
| Ballymena Bioenergy Limited | Belfast | 2015 |
| Ballymena Community Clusters Renewable Energy Project C.I.C. | Ballymena | 2018 |
| Ballymena Wind Park Limited | Stroud | 2008 |
| Ballynacross Wind Ltd | Belfast | 2015 |
| Ballynahinch Bess Ltd | Cookstown | 2023 |
| Ballynahinch Wind Ltd | Belfast | 2017 |
| Ballyness Renewables Limited | Londonderry | 2012 |
| Ballynoe Wind Ltd | Belfast | 2015 |
| Ballyrashane Solar Farm Limited | Coleraine | 2025 |
| Ballyross Energy Storage Limited | Kings Langley | 2024 |
| Ballyutoag Wind Farm Ltd | Omagh | 2014 |
| Balmangan AD Limited | Edinburgh | 2014 |
| Balmeanach Wind Farm Limited | Edinburgh | 2020 |
| Balmonth Energy Limited | Anstruther | 2013 |
| Balnamoon Renewables Limited | Glasgow | 2004 |
| Balnoon Wind Limited | Aberdeen | 2015 |
| Balring Energy Limited | Mintlaw | 2013 |
| Baluntonhill Limited | Girvan | 1997 |
| Balwyllo Bess Limited | Mirfield | 2023 |
| Bambers Wind Park Limited | Stroud | 1999 |
| Bamford Storage Facility Limited | Arundel | 2024 |
| Banbury Power Limited | Bristol | 2017 |
| Banc DU Energy Park Limited | Cardiff | 2020 |
| Bancroft Generation Limited | Kirkby Lonsdale | 2016 |
| Banff Limited | London | 2018 |
| Bankenergi Ltd | Reading | 2018 |
| Bankhead Energy Limited | Burntisland | 2014 |
| Banks Renewable Energy Limited | Durham | 2008 |
| Banks Renewables (Bowburn Solar Park) Limited | Houghton-Le-Spring | 2020 |
| Bankset Limited | London | 2012 |
| Bann Road Solar Project Limited | Hove | 2014 |
| Bapp&Co Ltd | Wellington | 2020 |
| Barachander Wind Farm Ltd | Alloa | 2024 |
| Baraka Homes Ltd | Halesowen | 2025 |
| Barakah Energy Ltd | Bolton | 2026 |
| Baranailt Ltd | Belfast | 2014 |
| Barber&Alderton Ltd | Salisbury | 2022 |
| Barbican Power Limited | Leeds | 2013 |
| Barbican Yacht Construction Limited | Plymouth | 1978 |
| Barbour Energy Limited | Bicester | 2002 |
| Barclay Curle Limited | Glasgow | 1884 |
| Bardhvac UK Ltd | Southampton | 2021 |
| Barfoot Energy Ltd | Bognor Regis | 2008 |
| Bargoed PV Limited | Saffron Walden | 2013 |