| Initiative Klimabetrug Stoppen e.V. | Berlin, Berlin | Visit site |
| Inlyte Energy | San Leandro, California | Visit site |
| InnSure | Cambridge, Massachusetts | Visit site |
| Innergex | Longueuil, Quebec | Visit site |
| Inno Energy Group | Sydney, New South Wales | Visit site |
| InnoVent | Villeneuve-d'Ascq, Nord | Visit site |
| Innova Sun | San Francisco del Rincón, Guanajuato | Visit site |
| Innovations Bangalore | Chitradurga, Karnataka | Visit site |
| Innovative Pipeline Projects Ltd. | Calgary, Alberta | Visit site |
| Innovative Solar Utility | San Jose, CA | Visit site |
| Innovcable | Dois Córregos, São Paulo | Visit site |
| Innovesta Energy Co.,Ltd. | Pak Kret, Nonthaburi | Visit site |
| Innowell Group | Chennai, Tamil Nadu | Visit site |
| Innowind Energy Solutions | Cambridge, Ontario | Visit site |
| Innpact | Luxembourg, Luxembourg | Visit site |
| Inpasa | São Paulo, São Paulo | Visit site |
| Inscio Roofs | IJsselstein, Utrecht | Visit site |
| Inspire Clean Energy | Mumbai, Maharashtra | Visit site |
| Insta GmbH | Lüdenscheid, North Rhine-Westphalia | Visit site |
| Installatøren Gruppen | Rolvsøy, Østfold | Visit site |
| Institut National de l'Économie Circulaire (INEC) | Paris, Île-de-France | Visit site |
| Institut Photovoltaïque d'Ile-de-France (IPVF) | Düsseldorf, North Rhine-Westphalia | Visit site |
| Instrumentos y Controles S.A. | Bogotá, Bogotá | Visit site |
| IntES International Engineering Solutions | Amsterdam, North Holland | Visit site |
| Intecsa | Madrid, Madrid | Visit site |
| IntegraRack | Las Vegas, Nevada | Visit site |
| Integral RISE | Maadi, Cairo | Visit site |
| Integrated Electrical Distributors | Fresno, California | Visit site |
| Integrated Home Energy | West Chester, Pennsylvania | Visit site |
| Integrated Sustainability | Calgary, Alberta | Visit site |
| Integrity Electrical Services | Tempe, Arizona | Visit site |
| Integrity Environmental Solutions | Henrico, Virginia | Visit site |
| Integrum Energy | Bengaluru, Karnataka | Visit site |
| Intel Corporation | Santa Clara, California | Visit site |
| IntelliSpatial | Perth, Western Australia | Visit site |
| Intelligent Green Solutions | Ithaca, New York | Visit site |
| InterContinental Energy | Singapore, Central Singapore Community Development Council | Visit site |
| Interlink Alternative Energy | Parklands, Western Australia | Visit site |
| Intermountain Electric, Inc. (IME) | Denver, Colorado | Visit site |
| Intermountain Electronics | Price, Utah | Visit site |
| International Bar Association | London, England | Visit site |
| International Brotherhood of Electrical Workers (IBEW) | Washington, District of Columbia | Visit site |
| International Brotherhood of Electrical Workers, Local 103 (IBEW 103) | Dorchester, Massachusetts | Visit site |
| Interpath | London, England | Visit site |
| Interstate Renewable Energy Council (IREC) | Long Beach, New York | Visit site |
| Interstates | Sioux Center, Iowa | Visit site |
| Intertechne | Curitiba, Paraná | Visit site |
| Intherpro LLC | Macapá, Amapá | Visit site |
| Intrax Consulting Group | Melbourne, Victoria | Visit site |
| Inventronics | Hangzhou Shi, Zhejiang | Visit site |
| Inventum Technologies B.V. | Houten, Utrecht | Visit site |
| Investable Oceans | New York, New York | Visit site |
| Investerra AG | St. Gallen, St. Gallen | Visit site |
| Investment Management Corporation of Ontario (IMCO) | Toronto, Ontario | Visit site |
| Invicto Energia Solar | Maringá, Paraná | Visit site |
| Invinity Energy Systems | London, England | Visit site |
| Ion Electrical Distributor | Orlando, Florida | Visit site |
| IonicBlue | East Rutherford, New Jersey | Visit site |
| Ipvisola Norge as | Ågotnes, Vestland | Visit site |
| Irby Utilities | Jackson, Mississippi | Visit site |
| Irish Solar Energy Association (ISEA) | Dublin, Dublin | Visit site |
| IronRidge | Hayward, California | Visit site |
| Isifloating | Beneixama, Alicante | Visit site |
| Isii-Tech | Saint-Étienne-du-Rouvray, Seine-Maritime | Visit site |
| Isoeste Construtivos Isotérmicos Ltda. | Goiás, Goiás | Visit site |
| IsolAccès Sàrl | La Plaine, Geneva | Visit site |
| Isotec Enerji | Dilovası, Kocaeli | Visit site |
| Italian Geothermal Forum | Roma, Rome | Visit site |
| Ivosis Group | Eyyübiye, Şanlıurfa | Visit site |
| iBASE ENERGY Co., Ltd. | 汐止區, New Taipei City | Visit site |
| iLumen | Atlanta, Georgia | Visit site |
| iRenergy | Merthyr Tydfil, Wales | Visit site |
| iRooFA | Round Hill, VA | Visit site |
| iSolar Solar Energy Solutions | Sevilla, Seville | Visit site |
| iStore Home | Perth, Western Australia | Visit site |
| imec | Leuven, Flemish Brabant | Visit site |
| innoEnergy GmbH | Weingarten-Kalthäusern, Thurgau | Visit site |
| innofas GmbH | Ingolstadt, Bavaria | Visit site |
| inoLECT, LLC | Baton Rouge, Louisiana | Visit site |