| Climate ER | London, United Kingdom | Visit site |
| Climate Group | London, United Kingdom | Visit site |
| Climate Lab | Vienna, Austria | Visit site |
| Climate Salad | Sydney, Australia | Visit site |
| Climate Scale | Brussels, Belgium | Visit site |
| Climate X | London, United Kingdom | Visit site |
| ClimatePartner | München, Germany | Visit site |
| Climatech Capital | London, United Kingdom | Visit site |
| Climeon | Kista, Sweden | Visit site |
| Climergia | Athina, Greece | Visit site |
| Clodesun all in one solar street light | Shenzhen Shi, China | Visit site |
| Cloover | Berlin, Germany | · |
| Cloudberry Clean Energy | Oslo, Norway | Visit site |
| Cloudberry Clean Energy | Karlstad, Sweden | Visit site |
| Clough | Australia | Visit site |
| Clyde Hydrogen Systems | Glasgow, United Kingdom | Visit site |
| Clúster Energético de Nuevo León | Monterrey, Mexico | Visit site |
| Clúster de l'Energia Eficient de Catalunya | Barcelona, Spain | Visit site |
| Clúster de l'Energia Eficient de Catalunya | Badalona, Spain | Visit site |
| Cn Enerji | Konak, Türkiye | Visit site |
| Co-Power | Laval, Canada | Visit site |
| Coastal Renewable Energy Technology Center | Mariveles, Philippines | Visit site |
| Coastwide Solar | Gold Coast, Australia | Visit site |
| Cobreflex Condutores Elétricos | Jandira, Brazil | Visit site |
| Coesa Energy | Torino, Italy | Visit site |
| Cogenfin | Forest, Belgium | Visit site |
| Cogenfin | Namur, Belgium | Visit site |
| Cogengreen | Namur, Belgium | Visit site |
| Cogeninfra | Borgaro Torinese, Italy | Visit site |
| Col Energy SAS | Bogotá, Colombia | Visit site |
| Cold Electric | 樹林區, Taiwan | Visit site |
| Colgas | Bogotá, Colombia | Visit site |
| Collective Energy Africa | Nairobi, Kenya | Visit site |
| Columbia Basin Trust | Castlegar, Canada | Visit site |
| Com-Cavi | Napoli, Italy | Visit site |
| Com-Cavi | Roma, Italy | Visit site |
| Com-Cavi | Milano, Italy | Visit site |
| Com-Cavi | Caserta, Italy | Visit site |
| Com-Cavi | Avezzano, Italy | Visit site |
| ComOps B.V. | Lijnden, Netherlands | Visit site |
| Comax | Nasr, Egypt | Visit site |
| ComfortZone AB | Täby, Sweden | Visit site |
| Comis S.r.l. | Pesaro, Italy | Visit site |
| Comité Interprofessionnel du Bois-Energie (CIBE) | Paris, France | Visit site |
| Commeo GmbH | Wallenhorst, Germany | · |
| Commeo Systems GmbH | Wallenhorst, Germany | · |
| Community Energy England | Sheffield, United Kingdom | Visit site |
| Compact Syngas Solutions Limited | Deeside, United Kingdom | Visit site |
| Compass Greenfield Development | Toronto, Canada | · |
| Complete Energy Solutions (CES) | Nasr, Egypt | Visit site |
| Complete Power Partners | Shepparton, Australia | Visit site |
| Compto Energies Renouvelables | بن عروس, Tunisia | Visit site |
| Comunità Energetiche S.p.A. | Terni, Italy | · |
| Con Energy AS | Vestby, Norway | · |
| Con4Mare | Hamburg, Germany | Visit site |
| ConWX | København, Denmark | Visit site |
| Concentrating Solar Power Services - CSP Services GmbH | Köln, Germany | Visit site |
| Condensator Dominit GmbH | Brilon, Germany | Visit site |
| Conduct Technical Solutions | Barendrecht, Netherlands | Visit site |
| ConectSolar | Recife, Brazil | Visit site |
| Conectrom Brasil | Natal, Brazil | · |
| Conergy | Singapore, Singapore | · |
| Conexio-PSE | Pforzheim, Germany | Visit site |
| Conga Ltd | Ipswich, United Kingdom | Visit site |
| Conloop GmbH | Freiburg im Breisgau, Germany | Visit site |
| Conquer Electronics | 五股區, Taiwan | Visit site |
| Conseco Enerji | Karşıyaka, Türkiye | Visit site |
| Consejo Insular de la Energía de Gran Canaria | Las Palmas de Gran Canaria, Spain | Visit site |
| Conserve Solutions | Manachanallur, India | Visit site |
| Consnant Technology | Shenzhen Shi, China | Visit site |
| Consolar Solare Energiesysteme GmbH | Frankfurt am Main, Germany | Visit site |
| Consolidated Contractors Company | Amarousio, Greece | Visit site |
| Consolidated Power Projects | Adelaide, Australia | Visit site |
| Constant Energy | Bangkok, Thailand | Visit site |
| Constructiv | Brussels, Belgium | Visit site |
| Contact Solar LTD | Chorley, United Kingdom | Visit site |
| Contact Solar LTD | Preston, United Kingdom | Visit site |
| Contemporary Amperex Technology Hungary Kft. | Debrecen, Hungary | Visit site |
| Contemporary Amperex Technology Thuringia GmbH | Arnstadt, Germany | · |
| Contendre Greenergy Limited | Mumbai, India | Visit site |
| Contigo Energía | Madrid, Spain | Visit site |
| ContourGlobal | Milano, Italy | Visit site |
| ConverterTec | Kempen, Germany | Visit site |
| Convion | Espoo, Finland | · |
| Coolpower Electrical | Harlow, United Kingdom | Visit site |
| Coolpower Electrical | Thetford, United Kingdom | Visit site |
| Cooper + Cooper Solar | Weymouth, United Kingdom | Visit site |
| Copa Solar AB | Rosersberg, Sweden | Visit site |
| Copenhagen Economics | København, Denmark | Visit site |
| Copenhagen Energy | København, Denmark | Visit site |
| Copenhagen Infrastructure Partners | Nordhavn, Denmark | Visit site |
| Copenhagen Infrastructure Service Co. | København, Denmark | Visit site |
| Copenhagen Offshore Partners | Nordhavn, Denmark | Visit site |
| CorPower Ocean | Hägersten, Sweden | · |
| CorSolar | São Paulo, Brazil | Visit site |
| Corab | Olsztyn, Poland | Visit site |
| Cordeel Belgium | Temse, Belgium | Visit site |
| Cordeiro Soluções em Energia | São Paulo, Brazil | Visit site |
| CorePack Renewable Energy | Nepean, Canada | Visit site |
| Coremax Tech | Shenzhen Shi, China | Visit site |
| Corigy Solar | Xiamen Shi, China | Visit site |
| Coro Energy Plc | London, United Kingdom | Visit site |
| Corporativo SOLES | Chihuahua, Mexico | Visit site |
| Cortex Design | Toronto, Canada | Visit site |
| Cory | London, United Kingdom | Visit site |
| CosMX | Zhuhai Shi, China | Visit site |
| Cosedil S.p.A | Santa Venerina, Italy | Visit site |
| Cosin Solar | Hangzhou Shi, China | Visit site |
| Cosmic PV Power Limited | Surat, India | Visit site |
| Cosmic Pv Power Limited | Surat, India | Visit site |
| Cosmos Innovation | Singapore, Singapore | Visit site |
| Cotek | 大溪區, Taiwan | Visit site |
| Couleenergy | Ningbo Shi, China | Visit site |
| Coulomb LiTech Private Limited | Mumbai, India | Visit site |
| Covengy - Energias Renováveis, Lda | Queluz, Portugal | Visit site |
| Coverwind Solutions, S.L.U. | Pedrafita do Cebreiro, Spain | · |
| Covolt | Veghel, Netherlands | · |
| Cowa Thermal Solutions AG | Mont-Royal, Canada | Visit site |
| Cox | Sevilla, Spain | · |
| Crea Energia Srl | Formigine, Italy | Visit site |
| Crepower Energy | Shenzhen Shi, China | Visit site |
| Crisil | Mumbai, India | Visit site |
| Cristec | Châteaulin, France | Visit site |
| Crossey Engineering, a Salas O'Brien Company | Toronto, Canada | Visit site |
| CrowdHouse Energy™ | Newcastle upon Tyne, United Kingdom | Visit site |
| Crown Technologies ZA | Johannesburg, South Africa | Visit site |
| Cruden Group | Edinburgh, United Kingdom | Visit site |
| Cuadristas Serca | Alcalá de Henares, Spain | Visit site |
| Cube Concepts GmbH - Innovative Energielösungen | Kaarst, Germany | Visit site |
| Cundall | Newcastle upon Tyne, United Kingdom | Visit site |
| Currie & Brown | London, United Kingdom | Visit site |
| Custom Solar Part of Mitie | Chesterfield, United Kingdom | Visit site |
| CyberDax Solar Company Ltd. | Shenzhen Shi, China | Visit site |
| Cybrid Technologies Inc. | Suzhou Shi, China | Visit site |
| Cybrid Technologies Inc. | Suzhou, China | Visit site |
| Cycle Capital | Montréal, Canada | · |
| Cycle Momentum | Montréal, Canada | Visit site |
| CycleØ | London, United Kingdom | Visit site |
| Cyclic Materials | Toronto, Canada | · |
| Cyenergy | Clapiers, France | Visit site |
| Cyient | Hyderabad, India | · |
| Cynergy | Dhaka, Bangladesh | Visit site |
| Cytek Solar Ltd | Nairobi, Kenya | Visit site |
| D Square Solar | Jaipur, India | Visit site |
| D Square Solar | India | Visit site |
| D&B Green Solution | Estinnes, Belgium | Visit site |
| D'Ieteren Energy | Ixelles, Belgium | Visit site |
| D'Ieteren Energy | Waasmunster, Belgium | Visit site |
| D'Ieteren Energy | Kortenberg, Belgium | Visit site |
| D+I is now Capgemini | Sydney, Australia | Visit site |