| CENTER FOR ANALYSIS AND DEVELOPMENT OF EFFECTIVE POLICIES (CADEP) | Kyiv, Ukraine | Visit site |
| CENTROTEC SE | Brilon, Germany | Visit site |
| CEPEMAR | Vitória, Brazil | Visit site |
| CER Italia | Lucca, Italy | Visit site |
| CER Italia | Porcari, Italy | Visit site |
| CERESS | Comunità Energetiche | Mozzo, Italy | Visit site |
| CERQ | Jena, Germany | · |
| CES clean energy solutions | Vienna, Austria | Visit site |
| CESI SpA | Milano, Italy | Visit site |
| CFP Energy | London, United Kingdom | · |
| CG SEMI Private Limited | Ahmedabad, India | Visit site |
| CG SEMI Private Limited | Mumbai, India | Visit site |
| CGN Brasil Energia | São Paulo, Brazil | Visit site |
| CGS | Amsterdam, Netherlands | Visit site |
| CHANGYUAN TECHNOLOGY GROUP(CYG) | Shenzhen Shi, China | Visit site |
| CHASE Technologies Industrial Lithium Ion Batteries | Alberton, South Africa | · |
| CHILWEE GROUP CO.,LTD | Huzhou Shi, China | Visit site |
| CHINT Green Energy | Hangzhou Shi, China | · |
| CHINT PVSTAR | Eschborn, Germany | · |
| CHISAGE POLSKA | Sokołów, Poland | Visit site |
| CHOSE Centre for Hybrid and Organic Solar Energy | Roma, Italy | Visit site |
| CIEL Group | Lontzen, Belgium | Visit site |
| CIEL Solar SA | Romanel-sur-Lausanne, Switzerland | Visit site |
| CIEL Solar SA | Cheseaux-sur-Lausanne, Switzerland | Visit site |
| CIESSE | Augusta, Italy | Visit site |
| CIMA+ | Laval, Canada | Visit site |
| CINDA ENGINEERING & CONSTRUCTION PRIVATE LIMITED | Noida, India | Visit site |
| CITROBOX ENERGIAS | Darmstadt, Germany | Visit site |
| CITY SOLAR | Ajmer, India | Visit site |
| CIXTEN | Bischwiller, France | · |
| CJK | The Ward, Ireland | Visit site |
| CJR Renewables | Leça do Balio, Portugal | Visit site |
| CJR-Cândido José Rodrigues | Selho, Portugal | Visit site |
| CKMiNE | Wenzhou Shi, China | Visit site |
| CLEAN ENERGY SYSTEMS, S.L. | Tavernes de la Valldigna, Spain | · |
| CLEAN-Air(Africa) | Nairobi, Kenya | Visit site |
| CLEAN-Air(Africa) | United Kingdom | Visit site |
| CLEAN-Air(Africa) | Cameroon | Visit site |
| CLEAN-Air(Africa) | Kenya | Visit site |
| CLEAN-Air(Africa) | Uganda | Visit site |
| CLEAN-Air(Africa) | Tanzania | Visit site |
| CLEAN-Air(Africa) | Rwanda | Visit site |
| CLHYNN | Besançon, France | Visit site |
| CLN Energy | Greater Noida, India | Visit site |
| CLOU ESS | Shenzhen Shi, China | · |
| CME - Copper Mountain Energy | Ho Chi Minh City, Vietnam | Visit site |
| CMEC 中东区域公司 | Dubai, United Arab Emirates | Visit site |
| CMI SOLAR | Mississauga, Canada | Visit site |
| CMS Albiñana & Suárez de Lezo | Madrid, Spain | Visit site |
| CMS Albiñana & Suárez de Lezo | Barcelona, Spain | Visit site |
| CMS Albiñana & Suárez de Lezo | Sevilla, Spain | Visit site |
| CMS SURVEYORS | Sydney, Australia | Visit site |
| CNR (Compagnie Nationale du Rhône) | Lyon, France | Visit site |
| CNR Construction | Pleumeleuc, France | Visit site |
| CNS Energy | Seoul, South Korea | Visit site |
| CNTE | China | Visit site |
| COBRA INGENIERIA | Guadalajara, Mexico | Visit site |
| COEPTUM | Gandra, Portugal | Visit site |
| COGECLIM | France | Visit site |
| COLOSSUN | Zaragoza, Spain | Visit site |
| COMAL SpA | Montalto di Castro, Italy | Visit site |
| COMBATT S.A. | Athina, Greece | Visit site |
| CONGEOCON | São Paulo, Brazil | Visit site |
| CONSEJO DE PROFESIONALES EN ENERGÍA FOTOVOLTAICA - CPEF | San José del Castillo, Mexico | Visit site |
| CONSGA BIC SAS | Bogotá, Colombia | Visit site |
| CONSTRUCCIONES RUBAU | Barcelona, Spain | Visit site |
| CONVERDAN A/S | Vojens, Denmark | Visit site |
| COPERGREEN - Intégrateur de Projets Photovoltaïques | Clermont-Ferrand, France | Visit site |
| CORE Energy Recovery Solutions | Reinsdorf, Germany | Visit site |
| CORE Geomatics | Calgary, Canada | Visit site |
| COREY ENERGY | Zapopan, Mexico | Visit site |
| COREY SOLAR | Zapotlanejo, Mexico | Visit site |
| COSPOWERS NEW ENERGY PVT. LTD. | Hyderabad, India | Visit site |
| CPB Contractors | Sydney, Australia | Visit site |
| CPC Germania GmbH & Co. KG | Rheine, Germany | Visit site |
| CPD Powerline Ltd | Armagh, United Kingdom | Visit site |
| CPM Engenharia - 35 anos | Vila Velha, Brazil | Visit site |
| CPM Engenharia - 35 anos | Passos, Brazil | Visit site |
| CR2P Photovoltaïque | Saint-Paul-lès-Dax, France | Visit site |
| CRE - Commission de régulation de l'énergie | Paris, France | Visit site |
| CRE - Commission de régulation de l'énergie | Vernon, France | Visit site |
| CREC - Clúster de Residus de Catalunya | Barcelona, Spain | Visit site |
| CRU | London, United Kingdom | Visit site |
| CS CLEAN SOLUTIONS GmbH | Ismaning, Germany | Visit site |
| CS Instruments Turkey | Pendik, Türkiye | Visit site |
| CS Instruments Turkey | Villingen-Schwenningen, Germany | Visit site |
| CS WIND Corp | Seoul, South Korea | Visit site |
| CS WIND Offshore | Aalborg, Denmark | Visit site |
| CS WIND TURKEY | Aliağa, Türkiye | Visit site |
| CS Wismar France | France | Visit site |
| CSB Battery | Taiwan | Visit site |
| CSBattery | Shenzhen Shi, China | · |
| CSPower Battery | Shenzhen Shi, China | Visit site |
| CST Energy | Chiva, Spain | Visit site |
| CTA Ltd. | Münsingen, Switzerland | · |
| CTCAP Group | Eschborn, Germany | Visit site |
| CTCI | 臺北市, Taiwan | Visit site |
| CTECHi | Burk's Falls, Canada | Visit site |
| CTF Solar GmbH | Dresden, Germany | · |
| CTG EYIL | Vellore, India | Visit site |
| CVE (Changing Visions of Energy) | Freiburg im Breisgau, Germany | Visit site |
| CVE Chile | Vitacura, Chile | Visit site |
| CVE South Africa | Cape Town, South Africa | Visit site |
| CW ENERJİ | Döşemealtı, Türkiye | Visit site |
| CWA Engineers Inc. | Vancouver, Canada | · |
| CWHI (CNOOD-Wenchong Heavy Industries) | Guangzhou Shi, China | Visit site |
| CWP Energy | Frodsham, United Kingdom | Visit site |
| CWP Energy | United Kingdom | Visit site |
| CWP Global | Singapore, Singapore | Visit site |
| CWind | Chelmsford, United Kingdom | Visit site |
| CYSORE | León, Mexico | Visit site |
| Cables RCT | Zaragoza, Spain | Visit site |
| Cableworld | Bolton, United Kingdom | Visit site |
| Cabur | Altare, Italy | Visit site |
| Cachelan | Markham, Canada | Visit site |
| Cactus Energy | Manchester, United Kingdom | Visit site |
| Cadre AS | Kristiansand, Norway | Visit site |
| Caeli Wind | Berlin, Germany | · |
| Cairn Risk | Glasgow, United Kingdom | Visit site |
| Caldera | Fareham, United Kingdom | · |
| Calderys | Paris, France | Visit site |
| Calibrate Energy Ltd | Alnwick, United Kingdom | Visit site |
| Calik Holding | Şişli, Türkiye | Visit site |
| Callens-Vyncke | Waregem, Belgium | Visit site |
| Calma sp. z o.o. | Białobrzegi, Poland | Visit site |
| Calom Solar | Bogotá, Colombia | Visit site |
| Caltech Group | Calgary, Canada | Visit site |
| Cambi | Asker, Norway | Visit site |
| Cambridge GaN Devices Ltd | Cambridge, United Kingdom | Visit site |
| Cambridge GaN Devices Ltd | 新莊區, Taiwan | Visit site |
| Camco | London, United Kingdom | Visit site |
| Camel Group | Xiangyang Shi, China | Visit site |
| Camille Bauer Metrawatt AG | Wohlen, Switzerland | Visit site |
| Canadian Climate Institute / Institut climatique du Canada | Bobcaygeon, Canada | Visit site |
| Canadian Council for Indigenous Business | Toronto, Canada | Visit site |
| Canadian Energy | Calgary, Canada | Visit site |
| Canadian Hydrogen Association (CHA) | Vancouver, Canada | Visit site |
| Canadian Steel Producers Association (CSPA) | Ottawa, Canada | Visit site |
| Canbat | Vancouver, Canada | Visit site |
| Candi Solar | Zürich, Switzerland | Visit site |
| Cando Solar | China | Visit site |
| Cando Solar | Changzhou Shi, China | Visit site |
| Canoe | Stavanger, Norway | Visit site |
| Canopus Drilling Solutions | Den Haag, Netherlands | · |
| Canopy Cameroun SARL | Yaounde, Cameroon | Visit site |
| Canopy Cameroun SARL | Paris, France | Visit site |
| Canopy Power | Singapore, Singapore | Visit site |
| Canopy Power | Melbourne, Australia | Visit site |
| Cansol Energy Solutions | Spain | Visit site |
| Capcora | Frankfurt am Main, Germany | Visit site |