| INTI-TECH | Santiago, Chile | Visit site |
| INTILION | Paderborn, Germany | Visit site |
| INTO-R | Gimpo-si, South Korea | Visit site |
| INTO-R | Gimpo-si, Republic of Korea | Visit site |
| INTO-R | USA | Visit site |
| INTO-R | China | Visit site |
| INVALL S.A. | Reus, Spain | Visit site |
| INVT Electric | Shenzhen Shi, China | Visit site |
| IOG 國際海洋集團 (Legacy) | 臺北市, Taiwan | Visit site |
| ION Chip Co., Ltd. | Seoul, South Korea | Visit site |
| IOWN Energy AB | Göteborg, Sweden | Visit site |
| IPG Energy | Hoddesdon, United Kingdom | Visit site |
| IPM Group | Bratislava, Slovakia | Visit site |
| IPOL Lubricants - GP Petroleums Ltd. | Mumbai, India | Visit site |
| IPOL Lubricants - GP Petroleums Ltd. | Uran, India | Visit site |
| IRC Projects | Albacete, Spain | Visit site |
| IRD Fuel Cells A/S | Odense, Denmark | Visit site |
| IREC - Institut de Recerca en Energia de Catalunya | Sant Adrià de Besòs, Spain | Visit site |
| IREC - Institut de Recerca en Energia de Catalunya | Tarragona, Spain | Visit site |
| IREDA Ltd. | New Delhi, India | Visit site |
| IREM | Susa, Italy | · |
| IRISOLARIS | Rousset, France | Visit site |
| IRSC for Renewable Energy Solutions | Egypt | · |
| IS SaveEnergy AG | Eschlikon, Switzerland | · |
| ISC Konstanz | Yarrambat, Australia | Visit site |
| ISC Training & Assembly GmbH | Rostock, Germany | Visit site |
| ISCOM SPA - Roofing | Pescantina, Italy | Visit site |
| ISELI ENERGIE AG | Wauwil, Switzerland | · |
| ISFH – Institut für Solarenergieforschung Hameln | Emmerthal, Germany | Visit site |
| ISG - automation GmbH | Rostock, Germany | Visit site |
| ISG-MOOLEX | Heiligenbrunn, Austria | Visit site |
| ISGroup | Perth, Australia | Visit site |
| ISIGENERE | Beneixama, Spain | Visit site |
| ISOLUX CORSAN | Madrid, Spain | Visit site |
| ISOPLUS Italy | Villamarzana, Italy | Visit site |
| ISOPLUS North America | Toronto, Canada | Visit site |
| ISOTEC Solar Ltd. | Dilovası, Türkiye | Visit site |
| ISS Global Forwarding | Parauapebas, Brazil | Visit site |
| ISS Global Forwarding | Dubai, United Arab Emirates | Visit site |
| ISTRICH | Yenimahalle, Türkiye | · |
| ITALSOL SRL | Arezzo, Italy | Visit site |
| ITI Powered | Victoria, Canada | Visit site |
| ITM Power | Sheffield, United Kingdom | · |
| ITO Navaids | Noordwijk, Netherlands | · |
| ITS WIND SERVICES LTD | United Kingdom | Visit site |
| ITalConn | Bassano del Grappa, Italy | Visit site |
| IVI Energia | São Paulo, Brazil | Visit site |
| IWELL | Utrecht, Netherlands | Visit site |
| IWEN Energy Institute gGmbH | Rostock, Germany | Visit site |
| IWP - Ingenieurbüro für Systemplanung GmbH | Stuttgart, Germany | Visit site |
| IX Renewables | Leiden, Netherlands | Visit site |
| IZI Solutions Durables | Courbevoie, France | Visit site |
| IZIVIA - Groupe EDF | Courbevoie, France | Visit site |
| Iberdrola Deutschland | Pontevedra, Argentina | Visit site |
| Iberdrola México | General Manuel Ávila Camacho, Mexico | Visit site |
| Iberian Solar Europe | València, Spain | Visit site |
| IbéricaRenovables | Sevilla, Spain | · |
| IceWind | Reykjavík, Iceland | Visit site |
| Iceland Geothermal | Reykjavík, Iceland | Visit site |
| Iceland Renewable Energy Cluster | Reykjavík, Iceland | Visit site |
| Ideal New Energy | Wuxi Shi, China | Visit site |
| Ies Solare S.r.l. | Bibbona, Italy | Visit site |
| Ies Solare S.r.l. | Livorno, Italy | Visit site |
| Igloo Environmental Limited | Braintree, United Kingdom | Visit site |
| Ignite Energy Access | Macapá, Brazil | Visit site |
| Ijes Solar | Castalla, Spain | Visit site |
| Ikigai Energy | London, United Kingdom | Visit site |
| Illumine Energy | Ernakulam, India | Visit site |
| Illuming Power Inc. | Vancouver, Canada | Visit site |
| Ilum China 意路姆 | Shanghai, China | Visit site |
| Ilumisol Energia Solar | Cascavel, Brazil | Visit site |
| ImWind | Vienna, Austria | Visit site |
| Imagine Powertree Private Limited | Gandhinagar, India | Visit site |
| Imbrego | Maarssen, Netherlands | Visit site |
| Imhotep.Industries | Freistadt, Austria | Visit site |
| Immersa Limited | Dursley, United Kingdom | · |
| Impact Clean Power Technology S.A. | Pruszków, Poland | Visit site |
| Impact Engineering | Vancouver, Canada | Visit site |
| Impact Engineering | Smithers, Canada | Visit site |
| Impact Hub Vienna | Vienna, Austria | Visit site |
| Imperix | Sion, Switzerland | Visit site |
| Impresa Pizzarotti & C. S.p.A. | Parma, Italy | Visit site |
| Impuls Energy Trading GmbH | Köln, Germany | Visit site |
| Impulse Green Energy Private Limited | Mumbai, India | Visit site |
| InEnergie | Utrecht, Netherlands | Visit site |
| InSolare Energy Limited | Ahmedabad, India | Visit site |
| InWarmte | Utrecht, Netherlands | Visit site |
| Inaccess by Power Factors | London, United Kingdom | · |
| Inbar Solar Energy | Modiin-Maccabim-Reut, Israel | · |
| Incap | Helsinki, Finland | Visit site |
| Inch Cape Offshore Limited | Edinburgh, United Kingdom | Visit site |
| Inclusive Green Growth in Egypt النمو الأخضر الشامل فى مصر | Piraquara, Brazil | · |
| Increase New Energy (Hunan) Co.,Ltd | China | Visit site |
| Increase New Energy (Hunan) Co.,Ltd | Shenzhen Shi, China | Visit site |
| Incubateur Savoie Technolac | Le Bourget-du-Lac, France | Visit site |
| IndSol Group AB | Malmö, Sweden | · |
| Independent Electricity System Operator (IESO) | Toronto, Canada | Visit site |
| Indi Energy | Roorkee, India | Visit site |
| India Agrivoltaics Alliance (IAA) | India | Visit site |
| India Agrivoltaics Alliance (IAA) | New Delhi, India | Visit site |
| Indian Biogas Association | Gurugram, India | Visit site |
| Indian Solar System Integrators Association | Hyderabad, India | Visit site |
| Indigenous Services Canada | Services aux Autochtones Canada | Gatineau, Canada | Visit site |
| Indo-German Energy Forum Support Office (IGEF-SO) | New Delhi, India | Visit site |
| Indonesia Infrastructure Finance | Jakarta, Indonesia | Visit site |
| Induscabos | Poá, Brazil | Visit site |
| Industria Solar Tracker | Brasília, Brazil | Visit site |
| Industrial Batteries Australia | Sydney, Australia | Visit site |
| Industrial Batteries Australia | Melbourne, Australia | Visit site |
| Industrial Batteries Australia | Brisbane, Australia | Visit site |
| Industrial Batteries Australia | Perth, Australia | Visit site |
| Industrial Batteries Australia | Adelaide, Australia | Visit site |
| Ineco Energy | Kenilworth, United Kingdom | · |
| Inecosolar | Jakarta, Indonesia | Visit site |
| Iner Energía | Albacete, Spain | Visit site |
| Inertia | Toronto, Canada | Visit site |
| Inferno Solar | Edmonton, Canada | Visit site |
| InfiSol Energy Limited | Aurangabad, India | Visit site |
| Infimeo | Bratislava, Slovakia | Visit site |
| Infineon Technologies | Neubiberg, Germany | Visit site |
| Infinia Solar | Noida, India | Visit site |
| Infinis | Northampton, United Kingdom | Visit site |
| Infinite Energy | Perth, Australia | · |
| InfraCredit | Nigeria | Visit site |
| InfraRed Iberia Holdings | Alcobendas, Spain | Visit site |
| InfraRoad Trading & Contracting LLC | الشيحانية, Qatar | Visit site |
| InfraRoad Trading & Contracting LLC | Doha, Qatar | Visit site |
| InfraRoad Trading & Contracting LLC | Al-Riyadh, Saudi Arabia | Visit site |
| InfraVia Capital Partners | Paris, France | Visit site |
| Infranity | Paris, France | Visit site |
| Infyos | London, United Kingdom | Visit site |
| IngegnoLab | Ragusa, Italy | Visit site |
| Ingenergía de México | San Juan Tehuixtitlán, Mexico | Visit site |
| Ingenieurbüro Böker GmbH | Lingen, Germany | Visit site |
| Ingenieurbüro GEHLEN | Düsseldorf, Germany | Visit site |
| Ingenieurbüro GEHLEN | Wuppertal, Germany | Visit site |
| Ingenieurgesellschaft IDEAS mbH | Thundorf in Unterfranken, Germany | Visit site |
| Ingenieurgesellschaft Mengü Ingenieure GmbH | Westerbork, Netherlands | Visit site |
| Ingenieurgesellschaft Mengü Ingenieure GmbH | Hamm, Germany | Visit site |
| Ingenium | Sydney, Australia | Visit site |
| Ingotta | Shenzhen Shi, China | Visit site |
| Ingélios | Saint-Martin-sur-le-Pré, France | Visit site |
| Inhenergy | Zhuhai Shi, China | Visit site |
| Initiative Klimabetrug Stoppen e.V. | Berlin, Germany | Visit site |
| InkPV | China | Visit site |
| Inka Solar | Lima, Peru | Visit site |
| Inlux Solar | China | Visit site |
| Innargi | København, Denmark | Visit site |
| Innergex | Longueuil, Canada | Visit site |
| Inno Energy Group | Sydney, Australia | Visit site |