| Bhiorain Hydro Ltd | Leeds | 2017 |
| Bhlaraidh Extension Wind Farm Limited | Perth | 2024 |
| Bhlaraidh Wind Farm Limited | Perth | 2020 |
| BHM Energy Ltd | Redditch | 2019 |
| BHT Energy Limited | London | 2016 |
| BIA Power (UK) Limited | London | 2026 |
| Biasan Energy Ltd | Stoke-On-Trent | 2021 |
| Bibby Energy Solutions Ltd | Liverpool | 2022 |
| Bicar Electrical Services Limited | Enfield | 2014 |
| Bice Energy Limited | Ashford | 2023 |
| Bicker Drove Limited | London | 2024 |
| Bicker FEN Solar Limited | Cheltenham | 2020 |
| Bicker FEN Windfarm Limited | London | 2008 |
| Bierlow Bess Limited | Mirfield | 2023 |
| Big Battery (Aird Farm) Limited | Glasgow | 2022 |
| Big Battery (Enrigg) Limited | Glasgow | 2022 |
| Big Battery (Fasnakyle) Limited | Glasgow | 2022 |
| Big Battery (Flatterton Farm) Limited | Glasgow | 2022 |
| Big Battery (Grudie Bridge) Limited | Glasgow | 2022 |
| Big Battery (Holmquarry Road) Limited | Glasgow | 2022 |
| Big Battery (Kerrow Farm) Limited | Glasgow | 2022 |
| Big Battery (Letham Farm) Limited | Glasgow | 2022 |
| Big Battery (Macleod) Limited | Glasgow | 2022 |
| Big Battery (MID Ardlaw) Limited | Glasgow | 2022 |
| Big Battery (Patterton) Limited | Glasgow | 2024 |
| Big Battery (Rannoch) Limited | Glasgow | 2022 |
| Big Battery (Saturland Farm B) Limited | Glasgow | 2022 |
| Big Battery (Saturland Farm) Limited | Glasgow | 2022 |
| Big Battery (Sheriff Faulds Farm 1) Limited | Glasgow | 2022 |
| Big Battery (UTS 1) Limited | Glasgow | 2022 |
| Big Battery (UTS 3) Limited | Glasgow | 2022 |
| Big Battery Company Limited | Glasgow | 2022 |
| Big FAT Group Ltd | Bexhill-On-Sea | 2021 |
| Big Green Energy Ltd | Amersham | 2021 |
| Big Oak Enterprises Limited | Hereford | 2012 |
| Big Power Ltd | London | 2022 |
| Big Red Utilities Limited | Clacton-On-Sea | 2026 |
| Big Solar Projects 1 Ltd | Shrewsbury | 2023 |
| Big Solar Projects 2 Ltd | Shrewsbury | 2024 |
| Big Solar Roofs Ltd | Radstock | 2016 |
| Big Wind Limited | Bradford | 2014 |
| Biggleswade Wind Farm Limited | London | 2012 |
| Bilbao Holdings Limited | Weybridge | 2024 |
| Bilbrook Renewables Limited | Shepton Mallet | 2025 |
| Bilbster Wind Farm Limited | Swindon | 2006 |
| Bilkey and Bray Limited | Truro | 2012 |
| Bill Smart Energy Ltd | Bournemouth | 2024 |
| Bill Tonks Ventilation Services Ltd | Mansfield | 2012 |
| Billam (Sheffield) Realisations Limited | Leeds | 1953 |
| Billcliff Energy Consulting Limited | Rhyl | 2014 |
| Billingham EFW Limited | Billingham | 2018 |
| Billingham Solar Limited | London | 2021 |
| Bilsborrow Solar Project Limited | Hove | 2014 |
| Bilsthorpe Solar Limited | London | 2012 |
| Bilsthorpe Wind Farm Limited | Kings Langley | 2010 |
| BIN Mountain Windfarm (N.I.) Limited | Belfast | 2003 |
| Bineri Limited | Suffolk | 2005 |
| Bingham Building Services Ltd | London | 2025 |
| Bingham Energy Limited | Derry | 2016 |
| Binka Ltd | Bromsgrove | 2023 |
| Binn Ecopark Hydrogen Limited | Roslin | 2023 |
| BIO CNG Ltd | Horsham | 2017 |
| BIO Dynamic (UK) Limited | Nottingham | 2013 |
| BIO Energy Europe Ltd | London | 2025 |
| BIO Energy Savings Ltd | London | 2022 |
| BIO GAS 51 Ltd | Craigavon | 2016 |
| BIO2CARBON Limited | Leicester | 2016 |
| Biochp Limited | Weston | 2011 |
| Biocore AD3 Limited | London | 2010 |
| Bioenergy Ecogas Ltd | London | 2021 |
| Bioenergy Group Limited | London | 2017 |
| Biofuels Group Limited | Ayr | 2021 |
| Biog-Uk Ltd | Telford | 2010 |
| Bioganix Generation Limited | Brigg | 2016 |
| Biogas (N.I.) Ltd | Cookstown | 2019 |
| Biogas 74 (NI) Ltd | Craigavon | 2018 |
| Biogas Energy Limited | Banbridge | 2015 |
| Biogas Maybole Limited | London | 2026 |
| Biogas Meden Ltd. | Guildford | 2014 |
| Biogas OPS 1 Limited | Solihull | 2024 |
| Biogas OPS 2 Limited | Buntingford | 2024 |
| Biogas OPS 3 Limited | Solihull | 2024 |
| Biogas OPS 4 Limited | Solihull | 2024 |
| Biogas OPS 5 Limited | Solihull | 2024 |
| Biogas OPS 6 Limited | Solihull | 2026 |
| Biogas OPS 7 Limited | Solihull | 2026 |
| Biogas West FEN Farm Limited | London | 2018 |
| Biogen (UK) Limited | Bedfordshire | 2005 |
| Biogen Bioenergy Limited | Milton Ernest | 2023 |
| Biogen Bryn Pica Limited | Bedfordshire | 2011 |
| Biogen EM Opco Limited | Bedford | 2013 |
| Biogen Gwyriad Limited | Bedfordshire | 2011 |
| Biogen Waen Limited | Bedfordshire | 2011 |
| Biomac Limited | Wick | 2017 |
| Biomass Future Generation Limited | Ely | 2010 |
| Biomass Renewable Energy Ltd | Omagh | 2015 |
| Biomass RS Limited | West Bromwich | 2017 |
| Biomass UK NO. 2 Limited | London | 2015 |
| Biomass UK NO. 3 Limited | London | 2015 |
| Biometan (UK) 1 Ltd | Leeds | 2024 |