Rainmaker Technology Funding, Investors & Competitors

Vistra Corp. is one of the largest power producers and retail energy providers in the USA. It owns 44 gigawatts of generation capacity, including natural gas (27 GW), nuclear (6.5 GW), coal (8.7 GW), and solar and battery storage (1.4 GW). The Cogentrix acquisition will add 5.5 GW of gas generation. Vistra's retail electricity business serves 5 million customers in 20 states, including almost a third of all Texas electricity consumers. Vistra emerged from the Energy Future Holdings bankruptcy as a stand-alone entity in 2016.

First Solar designs and manufactures solar photovoltaic panels, modules, and systems for use in utility-scale development projects. The company's solar modules use cadmium telluride to convert sunlight into electricity. This is commonly called thin-film technology. First Solar is the world’s largest thin-film solar module manufacturer. It has production lines in Vietnam, Malaysia, the United States, and India.

Northvolt was a Swedish battery manufacturer founded in 2015 to build the world's greenest, sustainably sourced lithium-ion batteries. Powered entirely by renewable energy (wind and hydro), Northvolt aimed to produce batteries with the lowest carbon footprint globally. Backed by heavyweights like Volkswagen and Goldman Sachs, it aimed to supply European automakers. However, facing severe scaling challenges and massive debt, the company filed for bankruptcy in 2024–2025.

Octopus Energy is a British energy supplier and technology group founded in 2015 that retails electricity and gas, invests in and manages renewable generation, and licenses software to other utilities. It has more than eight million retail customers worldwide, almost seven million of them in the United Kingdom, and became the largest UK electricity supplier after acquiring Shell Energy's retail arm in December 2023. Its Kraken platform, contracted to more than 50 million customer accounts, is licensed to third-party utilities, and its asset management arm runs over 400 wind and solar generators.

1Komma5° is a Berlin-headquartered ClimateTech company delivering integrated energy solutions at 80 sites in seven markets including Germany, Austria, and the US. It installs photovoltaics systems up to 10 kWp, battery storage with 15 kWh capacity, heat pumps for heating, and EV charging stations bundled into subscription models for residential and commercial properties.

Climeworks is a Zurich-based direct air capture company operating modular plants like Orca and Mammoth in Iceland. The technology extracts CO2 from ambient air for permanent underground storage via mineralization with Carbfix, serving corporate net-zero commitments under Puro.earth certification standards.

Gradiant is a Boston-headquartered cleantech company developing water treatment solutions for industrial sectors including microelectronics, pharmaceuticals, food and beverage, lithium extraction, and renewable energy. Its Carrier Gas Enhanced Separation technology removes contaminants from wastewater, enabling zero liquid discharge compliance. Deployed in facilities across Asia, Europe, and North America, Gradiant serves clients like Samsung and PepsiCo with modular systems for ultrapure water production and resource recovery.

Iberdrola is one of the largest utilities in the world with electric utility operations in nearly 40 countries. The company has a 57-gigawatt portfolio of hydro, wind, natural gas, and nuclear power plants. It is one of the largest owners of wind farms in the world, representing about 40% of its portfolio. Although the company has recently developed or acquired distribution and power generation assets in other geographic areas, Spain is still home to more than half of its power generation capacity. Iberdrola also owns and operates electricity and distribution networks in Spain, the UK, Brazil, and the US.

Danish company Orsted was named Dong Energy until the sale of all its oil and gas fields to Ineos in 2017, soon after the May 2016 initial public offering. Orsted is now focused on renewable assets, especially offshore wind farms. It operated 9.9 gigawatts of offshore wind farms at the end of 2024. The United Kingdom is the biggest country of operation, ahead of Germany and Denmark. The group intends to develop its footprint outside Europe with projects in Taiwan and in the US. Orsted also operates 4.8 GW of onshore wind and solar assets concentrated in the United States. The company is involved in more traditional utilities business like conventional power plants and gas supply, but these activities are noncore.

Uniper SE is a Germany-based energy generation and energy trading company. The firm operates through three segments: Flexible Generation, Greener commodities, and Green Generation. The Green Generation segment comprises emission-free power generation plants that the Uniper Group operates in Europe. The Flexible Generation segment comprises the power and heat generation plants that the Uniper Group operates in Europe to flexibly meet grid operators' requirements. The Greener Commodities segment bundles the energy trading and optimization activities and forms the commercial interface between the Uniper Group and the globally traded markets for energy and the major customers. The majority of revenue is derived from the Greener Commodities segment.

EDP is a vertically integrated utility company and is the largest generator, supplier, and distributor of electricity in Portugal. In addition to Portugal, EDP has sizable operations in Spain, Brazil, and the US. EDP owns 71% of EDP Renovaveis, the fourth-largest wind power owner/operator in the world. EDP delisted Energias do Brasil in August 2023 after buying out the 46% minorities.

Constellation Energy Corp producer of carbon-free energy and a supplier of energy products and services. The company offers generating capacity that includes nuclear, wind, solar, natural gas, and hydroelectric assets. It sells electricity, natural gas, and other energy-related products and sustainable solutions to various types of customers, including distribution utilities, municipalities, cooperatives, and commercial, industrial, public sector, and residential customers in markets across multiple geographic regions. Its operating segments and reporting units are Mid-Atlantic, Midwest, New York, ERCOT, and Other Power Regions.

ACWA Power Co is engaged in developing, investing, operating, and maintaining power generation, water desalination, and green hydrogen production plants, and bulk sale of electricity. The company's segments include Thermal and Water Desalination, Renewables, and Others. It generates maximum revenue from the Thermal and Water Desalination segment. Geographically, the company generates maximum revenue from Saudi Arabia, followed by other markets in the Middle East and Africa.

Founded in 1947 through a nationalization act, Verbund is the leading power producer in Austria. The Austrian state owns 51% of its capital. Hydro accounts for more than 90% of the total power output. Hydro power is generated from reservoirs and pumped storage plants in the Austrian Alps, and run-of-river plants in Austria and southern Germany. Total hydro capacity amounts to 8.4 GW. Verbund also owns the Austrian electricity grid through its fully owned subsidiary AP. In 2021, the firm acquired 51% of Gas Connect Austria, a gas transmission and distribution system operator. The group also owns one CCGT and is involved in trading and development of wind and solar capacity.

Fortum Oyj is a Finnish energy company that operates power plants that use renewable energy sources (hydro, nuclear, and solar power) to sell electricity, heat, cooling, and power products and services. The company mainly operates in Nordic and Baltic countries, Russia, Poland, and India. Its main divisions of the company are generation (large-scale power production), city solutions (sustainable energy solutions), Russia (all Russian operations), technology and new ventures (research and development and in-house incubator for startups), mergers and acquisitions, and solar and wind development. The company's operating segments are Generation, Consumer Solutions, and Other Operations.

PT Barito Renewables Energy Tbk, along with its subsidiaries, operates as a geothermal and wind energy power producer in Indonesia. Its project portfolio comprises Wayang Windu, Salak, Sidrap I, and Darajat. The company generates maximum revenue from the generation and sale of electricity in Indonesia.

Kansai Electric Power Co Inc is a Japan-based company that provides energy and information technology solutions. The company operates in four business segments. The Energy segment offers electricity, gas, and utility solutions. The Information and Communications segment provides comprehensive communication services. The Lifestyle/Business Solutions segment delivers consumer and business-related services. The Power Transmission and Distribution segment ensures a safe and reliable electricity supply from a neutral and fair standpoint. It generates the majority of its revenue from the Energy business segment.

Enilive is a Rome-headquartered subsidiary of Eni focused on sustainable mobility services. The company delivers integrated low-carbon solutions including biomethane production facilities, car-sharing fleets, and refueling stations for alternative fuels. Enilive operates across Italy with a network supporting electric vehicle charging and hydrogen infrastructure, advancing decarbonization in transportation through public-private partnerships.