| Bryt Energy Limited | Birmingham | 2016 |
| BS Air Ltd | Bude | 2012 |
| BSI Wind Ltd | Omagh | 2014 |
| BSL Electrical (NI) Ltd | Antrim | 2010 |
| BSR Applications Limited | Shepton Mallet | 2012 |
| BSR Energy 2 Limited | Shepton Mallet | 2022 |
| BSR Energy 4 Limited | Shepton Mallet | 2026 |
| BSR Energy Holdings 2 Limited | Shepton Mallet | 2022 |
| BSR Energy Holdings 3 Limited | Shepton Mallet | 2022 |
| BSR Energy Holdings 4 Limited | Shepton Mallet | 2026 |
| BSR Energy Holdings Limited | Shepton Mallet | 2015 |
| BSR O&M Limited | Shepton Mallet | 2021 |
| Bssl Cambsbed 1 Ltd | London | 2022 |
| Bssl East Ayrshire 1 Ltd | London | 2022 |
| Bssl Herts 2 Ltd | London | 2020 |
| Bssl Herts 3 Ltd | London | 2020 |
| Bssl Lincs 1 Ltd | London | 2022 |
| Bssl Oxfordshire 1 Ltd | London | 2024 |
| Bssl Projects Holdings Limited | London | 2026 |
| Bssl Projects Limited | London | 2026 |
| Bssl Stevenage Bess Ltd | London | 2021 |
| Bssl Suffolk 1 Ltd | London | 2020 |
| Bubbles Air Conditioning Ltd | Biggin Hill | 2024 |
| Bubney Energy Centre Limited | London | 2020 |
| Buchan Offshore Wind Limited | Glasgow | 2022 |
| Buchan Wind Power (BWP) Ltd | London | 2010 |
| Buckinghamshire Electrical Limited | High Wycombe | 2017 |
| Buckland Ripers Renewables Limited | Shepton Mallet | 2026 |
| Bucklesham Solar Limited | Cheltenham | 2022 |
| Buckley Plumbing, Heating & Cooling Limited | Liverpool | 2018 |
| Buckley Sheet Metal Ltd | Milnrow | 2009 |
| Buckny Hydro Scheme Limited | Edinburgh | 2016 |
| Buckside Limited | Ayrshire | 2023 |
| Budget Energy Limited | Belfast | 2009 |
| Bufan Power Holding Limited | Croydon | 2020 |
| Buffalo Energy Limited | London | 2016 |
| Bughtknowes WT Ltd | Motherwell | 2013 |
| Building Envelope Technologies Limited | Banbridge | 2016 |
| Building Solutions Warrington Ltd | Warrington | 2023 |
| BUK23 Limited | Edinburgh | 2023 |
| Bulb Energy Ltd | Birmingham | 2013 |
| Bullamoor Wind Farm Limited | Milnthorpe | 2009 |
| Bullen Power Limited | Norwich | 2023 |
| Bulls Head Solar Limited | London | 2013 |
| Bulworthy Solar Limited | London | 2024 |
| Bumpers Solar Limited | Reading | 2015 |
| Bunavoneader Hydro Limited | St. Albans | 2013 |
| Bunlougher Wind Limited | Enniskillen | 2013 |
| Bunns Hill Solar Limited | Gatwick, West Sussex | 2015 |
| Buntington Green Energy Centre Ltd | Bristol | 2022 |
| Buolectric Technologies Limited | Coventry | 2023 |
| Burcot Solar Farm Limited | London | 2021 |
| Burcroft Solar Parks Limited | London | 2013 |
| Burdass Renewables Limited | Bridlington | 2014 |
| Burdon Grange Energy Centre Limited | Norwich | 2020 |
| Burel Energy Ltd | London | 2021 |
| Burgar Hill Energy Limited | Orkney | 2024 |
| Burgar Hill Renewables Limited | Orkney | 2006 |
| Burn Hydro Limited | Hillsborough | 2015 |
| Burn Side Wind Farm Limited | Houghton-Le-Spring | 2026 |
| Burnbank Energy Centre Limited | Norwich | 2021 |
| Burnbrae & White Lion Wind Farms Limited | London | 2012 |
| Burnbrae Wind Farm Ltd | Hamilton | 2025 |
| Burnell Electrical Contractors Ltd | Wells | 2017 |
| Burnett Power & Lighting Ltd | Corbridge | 2026 |
| Burnham and Weston Energy CIC | Redruth | 2017 |
| Burnham Wick Solar Limited | Hove | 2013 |
| Burnhope Renewables Limited | Derby | 2024 |
| Burnley Bess Limited | London | 2022 |
| Burnquarter Limited | Ballymoney | 2013 |
| Burnthouse Farm Limited | Kings Langley | 2012 |
| Burnthouse Solar Limited | Bristol | 2014 |
| Burntwood Air Conditioning Limited | Burntwood | 2023 |
| Burrowton Farm Solar Park Limited | London | 2012 |
| Burstwick Bess Limited | Wilmslow | 2025 |
| Burton Agnes Renewables Limited | Guildford | 2015 |
| Burton Air Conditioning Limited | Sleaford | 1999 |
| Burton Powerlines Ltd | Skegness | 2025 |
| Burton Top Solar Limited | London | 2021 |
| Burton Wold Wind Farm (Trading) Limited | London | 2005 |
| Burton Wold Wind Farm South Ltd | London | 2015 |
| Burtonhead Road Power Limited | London | 2018 |
| Burwell 11 Solar Limited | London | 2019 |
| Burwell AL Limited | London | 2022 |
| Burwell Green Energy Centre Ltd | Faversham | 2022 |
| Bury Green Farm Solar Limited | Hove | 2015 |
| Bury Power Limited | Bristol | 2015 |
| Bushbury Green NG Limited | London | 2022 |
| Bushmills Hydro-Electric Company Limited | Coleraine | 2007 |
| Business Electric Solution Ltd | Wednesbury | 2025 |
| Business Electricity UK Limited | Derbyshire | 2007 |
| Business Energies Ltd | London | 2017 |
| Business Energy Advisors Ltd | Newport | 2003 |
| Business Energy Brokers Limited | West Drayton | 2017 |
| Business Energy for Less Ltd | Northampton | 2014 |
| Business Energy UK Online Limited | Manchester | 2025 |
| Business Reduction Services (NW) Limited | Preston | 2023 |
| Business Solution(Uk) Limited | Dagenham | 2019 |
| Business Support Centre (NW) Limited | Blackpool | 2023 |
| Business Utilities Group Ltd | Stratford-Upon-Avon | 2019 |