| HyWaves | Bedford, United Kingdom | Visit site |
| HyWaves | Antrim, United Kingdom | Visit site |
| Hybrid Power Solutions | Etobicoke, Canada | Visit site |
| Hybrid Solar Energy Solutions | Brisbane, Australia | Visit site |
| Hybrytec | Itagüí, Colombia | Visit site |
| Hycamite | Kokkola, Finland | Visit site |
| Hycube | Mannheim, Germany | Visit site |
| HydePoint | Stavanger, Norway | Visit site |
| HydraB | Oxford, United Kingdom | Visit site |
| Hydrexia | Shanghai, China | · |
| Hydrix | Melbourne, Australia | Visit site |
| Hydro One | Toronto, Canada | Visit site |
| Hydro Québec | Québec, Canada | Visit site |
| Hydro Rein | Oslo, Norway | Visit site |
| Hydro Tasmania | Hobart, Australia | Visit site |
| Hydro X | Jerusalem, Israel | Visit site |
| HydroWing Ltd | Penryn, United Kingdom | Visit site |
| Hydrobox | Brussels, Belgium | Visit site |
| Hydrobox | Belgium | Visit site |
| Hydrogen Council | Brussels, Belgium | Visit site |
| Hydrogen Refinery | London, United Kingdom | Visit site |
| Hydrogen Refueling Solutions - HRS | Moineville, France | Visit site |
| Hydrogen Scotland | Edinburgh, United Kingdom | Visit site |
| Hydrogen Solutions Ltd | London, United Kingdom | · |
| Hydrogen UK | London, United Kingdom | Visit site |
| HydrogenPro | Porsgrunn, Norway | · |
| Hydrogenics | Mississauga, Canada | Visit site |
| Hydronex | Steenwijk, Netherlands | Visit site |
| Hydrospider AG | Niedergösgen, Switzerland | Visit site |
| Hydrostadium | Annecy, France | Visit site |
| Hydrostor | Toronto, Canada | Visit site |
| Hydryx | Amsterdam, Netherlands | Visit site |
| Hyfindr | Stuttgart, Germany | · |
| Hygen Energy | Oxford, United Kingdom | Visit site |
| Hygreen Energy | Madrid, Spain | Visit site |
| Hylenr Technologies Private Limited | Hyderabad, India | Visit site |
| Hymeth | Malmö, Sweden | Visit site |
| Hymonic | Rotterdam, Netherlands | · |
| Hyosung Heavy Industries | Seoul, South Korea | Visit site |
| Hyper Green | Jaipur, India | Visit site |
| HyperHeat | Offenburg, Germany | · |
| Hyperion Renewables | Lisboa, Portugal | Visit site |
| Hyperthermics | Ulsteinvik, Norway | Visit site |
| Hypontech | 蘆洲區, Taiwan | Visit site |
| Hyren | Madrid, Spain | Visit site |
| Hystar | Oslo, Norway | · |
| HÖRMANN Energy Solutions GmbH | Wolfsburg, Germany | Visit site |
| Hälg Group | St. Gallen, Switzerland | Visit site |
| Hälg Group | Aarau, Switzerland | Visit site |
| Hälg Group | Arosa, Switzerland | Visit site |
| Hälg Group | Basel, Switzerland | Visit site |
| Hälg Group | Bern, Switzerland | Visit site |
| Hälg Group | Bütschwil, Switzerland | Visit site |
| Hälg Group | Chur, Switzerland | Visit site |
| Hälg Group | Givisiez, Switzerland | Visit site |
| Hälg Group | Plan-les-Ouates, Switzerland | Visit site |
| Hälg Group | Herzogenbuchsee, Switzerland | Visit site |
| Hälg Group | Kreuzlingen, Switzerland | Visit site |
| Hälg Group | La Chaux-de-Fonds, Switzerland | Visit site |
| Hälg Group | Lantsch, Switzerland | Visit site |
| Hälg Group | Lucerne, Switzerland | Visit site |
| Hälg Group | Ebikon, Switzerland | Visit site |
| Hälg Group | Münchenstein, Switzerland | Visit site |
| Hälg Group | Marin-Epagnier, Switzerland | Visit site |
| Hälg Group | Otelfingen, Switzerland | Visit site |
| Hälg Group | Jona, Switzerland | Visit site |
| Hälg Group | Rotkreuz, Switzerland | Visit site |
| Hälg Group | Samedan, Switzerland | Visit site |
| Hälg Group | Schlieren, Switzerland | Visit site |
| Hälg Group | Bramois, Switzerland | Visit site |
| Hälg Group | Spreitenbach, Switzerland | Visit site |
| Hälg Group | Tinizong, Switzerland | Visit site |
| Hälg Group | Villars-Sainte-Croix, Switzerland | Visit site |
| Hälg Group | Wil, Switzerland | Visit site |
| Hälg Group | Winterthur, Switzerland | Visit site |
| Hälg Group | Wallisellen, Switzerland | Visit site |
| Hälg Group | Zürich, Switzerland | Visit site |
| Hörburger GmbH & Co KG | Altach, Austria | Visit site |
| IAV GmbH | Berlin, Germany | · |
| IAV Morocco | Casablanca, Morocco | Visit site |
| IAV Poland | Opole, Poland | Visit site |
| IAV Poland | Berlin, Germany | Visit site |
| IB Energy | Newcastle upon Tyne, United Kingdom | Visit site |
| IB SOLAR | New Delhi, India | · |
| IBIS Power | Eindhoven, Netherlands | Visit site |
| IBP Ingenieure GmbH | München, Germany | Visit site |
| IBP Ingenieure GmbH | Aschheim, Germany | Visit site |
| IBP Ingenieure GmbH | Würzburg, Germany | Visit site |
| IBT SOLAR | Beşiktaş, Türkiye | Visit site |
| IBW Surveyors | Bowmanville, Canada | Visit site |
| ICIDE Energía Solar Fotovoltaica | Cartagena, Spain | Visit site |
| ICIS | London, United Kingdom | Visit site |
| ICO S.a.s. di Ing. Fornai & C | Alzano Lombardo, Italy | Visit site |
| ID Energy Group | Ciudad Real, Spain | Visit site |
| IDCM | London, United Kingdom | Visit site |
| IDCM | Amstelveen, Netherlands | Visit site |
| IDCM | Paris, France | Visit site |
| IDEAL SOLAR ENERGY LTD. | Jerusalem, Israel | Visit site |
| IDEAL SOLAR ENERGY LTD. | Kishor, Israel | Visit site |
| IDEEMATEC | Wallerfing, Germany | · |
| IDEX | Boulogne-Billancourt, France | Visit site |
| IDNAMIC | South Sudan | Visit site |
| IDOM Consulting, Engineering, Architecture | Bilbao, Spain | Visit site |
| IDOM Environment | Bilbao, Spain | Visit site |
| IEETek | Zhuhai Shi, China | Visit site |
| IEL Etudes et Installations Photovoltaïques | France | · |
| IES ENGINEERING SRL | Livorno, Italy | Visit site |
| IESSA (Illumination Engineering Society of South Africa) | Johannesburg, South Africa | Visit site |
| IFBF - International Flow Battery Forum | Malmesbury, United Kingdom | Visit site |
| IFM Investors | Melbourne, Australia | Visit site |
| IFPL | Newport, United Kingdom | Visit site |
| IG Renewables | London, United Kingdom | Visit site |
| IG Windkraft | Vienna, Austria | Visit site |
| IGEAM | Roma, Italy | Visit site |
| IGNES - Industriels des solutions électriques et numériques du bâtiment | France | Visit site |
| IGNES - Industriels des solutions électriques et numériques du bâtiment | Paris, France | Visit site |
| IHK für München und Oberbayern | München, Germany | Visit site |
| IHK für München und Oberbayern | Ingolstadt, Germany | Visit site |
| IHK für München und Oberbayern | Mühldorf am Inn, Germany | Visit site |
| IHK für München und Oberbayern | Rosenheim, Germany | Visit site |
| IJGlobal | London, United Kingdom | Visit site |
| IKB Sonnenstrom GmbH | Innsbruck, Austria | · |
| IKPT | Jakarta, Indonesia | Visit site |
| ILOS | Karlsruhe, Germany | Visit site |
| IM Efficiency | Helmond, Netherlands | Visit site |
| IMARTEC ENERGIA | Lleida, Spain | Visit site |
| IMB Energy Systems GmbH | Roth, Germany | Visit site |
| IMB Energy Systems GmbH | Rheinau, Germany | Visit site |
| IMS Heat Pumps Limited | Perth, United Kingdom | Visit site |
| INA SOLAR | Jaipur, India | · |
| INDEFOL SOLAR | Ho Chi Minh City, Vietnam | Visit site |
| INDICA Renewables | Port Louis, Mauritius | · |
| INDUS Environmental Services Pvt. Ltd. | New Delhi, India | Visit site |
| INERCO | La Rinconada, Spain | Visit site |
| INERGY Solutions | Antananarivo, Madagascar | · |
| INESC Microssistemas e Nanotecnologias | Póvoa de Santo Adrião, Portugal | Visit site |
| INESC Microssistemas e Nanotecnologias | Unhos, Portugal | Visit site |
| INESC Microssistemas e Nanotecnologias | Porto Salvo, Portugal | Visit site |
| INESC TEC | Porto, Portugal | Visit site |
| INFELC | Abu Dhabi, United Arab Emirates | Visit site |
| INGENIERIA Y OBRA CIVIL CHAVARRI SL | Burgos, Spain | Visit site |
| INIKTI | Vilnius, Lithuania | · |
| INJECT SOLAR LLP | Pune, India | Visit site |
| INL - International Iberian Nanotechnology Laboratory | Braga, Portugal | Visit site |
| INNIO Group | Jenbach, Austria | Visit site |
| INNO ENERGY 2025 | Ouargla, Algeria | Visit site |
| INNOVIS Consulting | Adelaide, Australia | Visit site |
| INPAL Energie | Chaponnay, France | Visit site |
| INSOS | Karatay, Türkiye | Visit site |
| INSTRA Ingenieros | A Coruña, Spain | Visit site |