Company lists · Data refreshed September 2026

Top 25 Cleantech accelerators based in the United States

Name: Cleantech accelerators based in the United States
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 19, 2026 818 companies tracked

RevenueBase identified 818 cleantech accelerators headquartered in the United States as of September 2026 and tracks 11,696 professional contacts across them, including 2,828 with verified work emails. New York is the largest hub.

This list covers cleantech accelerators headquartered in the United States, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Every row shows the company's own description, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed September 19, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.

How to read this list HQ checked on every row RevenueBase Smart Search rating on every row Refreshed Sep 19, 2026 86% judged on-target in blind review

818Companies

11,696Contacts tracked

2,828Verified emails

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The 25 largest cleantech accelerators based in the United States

Ranked by team size

Top 25 of 818 cleantech accelerators based in the United States, ranked by team size, largest first. Data refreshed Sep 19, 2026. RevenueBase Smart Search rates how each company's information relates to cleantech accelerators: strong evidence (its own description names it), partial (names part of it), indirect (matched on the rest of its profile rather than the description shown). Click a contact count to view that company's people.
#	Company	RevenueBase Smart Search	Headquarters	Employees	Contacts
1	Techstars	Indirect evidence	New York City, NY, United StatesHQ checked Sep 19, 2026	n/a	1,803 contacts →
	Indirect evidence “Techstars helps founders scale their startups into world-changing businesses.” Source: RevenueBase Database · checked Sep 19, 2026
2	Powur, PBC	Indirect evidence	San Diego, United StatesHQ checked Sep 19, 2026	n/a	1,199 contacts →
	Indirect evidence “The Powur Mission: Accelerate the adoption of clean energy worldwide We're empowering our community of homeowners and advisors to thrive in the global shift to sustainable energy.” Source: RevenueBase Database · checked Sep 19, 2026
3	Palmetto	Indirect evidence	Charlotte, NC, United StatesHQ checked Sep 19, 2026	201-500	539 contacts →
	Indirect evidence “Palmetto is a leading clean tech company on a mission to accelerate the transition to a clean energy future.” Source: RevenueBase Database · checked Sep 19, 2026
4	Alchemist Accelerator	Partial evidence	San Francisco, CA, United StatesHQ checked Sep 19, 2026	n/a	321 contacts →
	Partial evidence “The Alchemist Accelerator is a venture-backed initiative focused on accelerating the development of seed-stage ventures that monetize from enterprises (not consumers).” Source: RevenueBase Database · checked Sep 19, 2026
5	Energy & Environmental Research Center	Indirect evidence	Grand Forks, ND, United StatesHQ checked Sep 19, 2026	201-500	213 contacts →
	Indirect evidence “The Energy & Environmental Research Center (EERC) is recognized as one of the world's leading developers of cleaner, more efficient energy to power the world and environmental…” Source: RevenueBase Database · checked Sep 19, 2026
6	LOS Angeles Cleantech Incubator Laci	Partial evidence	Los Angeles, CA, United StatesHQ checked Sep 19, 2026	51-200	163 contacts →
	Partial evidence “Los Angeles Cleantech Incubator (LACI) is creating an inclusive green economy for the people of Los Angeles by unlocking innovation by working with startups to accelerate the…” Source: RevenueBase Database · checked Sep 19, 2026
7	Breakthrough Energy	Indirect evidence	Kirkland, United StatesHQ checked Sep 19, 2026	51-200	159 contacts →
	Indirect evidence “Breakthrough Energy backs companies developing the next generation of clean energy solutions.” Source: RevenueBase Database · checked Sep 19, 2026
8	Cleanchoice Energy	Partial evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	51-200	155 contacts →
	Partial evidence “CleanChoice Energy is a cleantech company that empowers people and businesses to easily access climate solutions.” Source: RevenueBase Database · checked Sep 19, 2026
9	Massachusetts Clean Energy Center	Indirect evidence	Boston, MA, United StatesHQ checked Sep 19, 2026	51-200	149 contacts →
	Indirect evidence “The Massachusetts Clean Energy Center is a state economic development agency dedicated to accelerating the growth of the clean energy and climatetech sector across the…” Source: RevenueBase Database · checked Sep 19, 2026
10	NEW Energy Nexus	Partial evidence	Berkeley, CA, United StatesHQ checked Sep 19, 2026	51-200	136 contacts →
	Partial evidence “New Energy Nexus (NEX) is the world's leading ecosystem of funds and accelerators supporting diverse clean energy entrepreneurs to thrive, from emerging tech through to clean…” Source: RevenueBase Database · checked Sep 19, 2026
11	Cleantech Open	Strong evidence	Los Angeles, CA, United StatesHQ checked Sep 19, 2026	11-50	132 contacts →
	Strong evidence “The Cleantech Open runs the world's largest cleantech accelerator.” Source: RevenueBase Database · checked Sep 19, 2026
12	Sublime Systems	Indirect evidence	Somerville, MA, United StatesHQ checked Sep 19, 2026	51-200	131 contacts →
	Indirect evidence “Sublime Systems is leading a swift and massive transition to a clean cement manufacturing future.” Source: RevenueBase Database · checked Sep 19, 2026
13	Connectm Technology Solutions	Indirect evidence	Marlborough, MA, United StatesHQ checked Sep 19, 2026	51-200	131 contacts →
	Indirect evidence “ConnectM is a clean energy technology and solutions provider for residential and light commercial buildings and all-electric original equipment manufacturers with a proprietary…” Source: RevenueBase Database · checked Sep 19, 2026
14	Silicon Catalyst	Partial evidence	Santa Clara, CA, United StatesHQ checked Sep 19, 2026	11-50	126 contacts →
	Partial evidence “Silicon Catalyst is the only incubator + accelerator focused on the Global Semiconductor Industry including Chips, Chiplets, Materials, IP and Silicon fabrication-based Photonics…” Source: RevenueBase Database · checked Sep 19, 2026
15	NERD	Indirect evidence	Gilbert, AZ, United StatesHQ checked Sep 19, 2026	51-200	116 contacts →
	Indirect evidence “To attract the best Nerds on the planet and “Nerdify” customers with innovative solutions that reduce energy consumption and produce clean, renewable energy.” Source: RevenueBase Database · checked Sep 19, 2026
16	Entrepreneurs Roundtable Accelerator	Partial evidence	NY, United StatesHQ checked Sep 19, 2026	n/a	114 contacts →
	Partial evidence “Entrepreneurs Roundtable Accelerator (ERA) is New York City’s leading technology accelerator and early-stage venture capital fund.” Source: RevenueBase Database · checked Sep 19, 2026
17	Cleantech Group	Indirect evidence	San Francisco, CA, United StatesHQ checked Sep 19, 2026	11-50	110 contacts →
	Indirect evidence “Winning in clean technologies is complex-new technologies emerge, policies shift, and it’s hard to know which opportunities will scale and which will fail.” Source: RevenueBase Database · checked Sep 19, 2026
18	Greentown Labs	Indirect evidence	Somerville, MA, United StatesHQ checked Sep 19, 2026	51-200	94 contacts →
	Indirect evidence “Greentown Labs is a 501(c)(3) nonprofit accelerating climatetech innovation for the planet, people, and prosperity.” Source: RevenueBase Database · checked Sep 19, 2026
19	Syzygy Plasmonics	Indirect evidence	Houston, TX, United StatesHQ checked Sep 19, 2026	11-50	80 contacts →
	Indirect evidence “Syzygy Plasmonics is a technology company decarbonizing chemical production with its proprietary light-driven reactor technology.” Source: RevenueBase Database · checked Sep 19, 2026
20	Onyx Renewables	Indirect evidence	New York, NY, United StatesHQ checked Sep 19, 2026	51-200	67 contacts →
	Indirect evidence “Onyx Renewables is a leading provider of predictable, affordable clean energy solutions nationwide.” Source: RevenueBase Database · checked Sep 19, 2026
21	Resurety	Indirect evidence	Boston, MA, United StatesHQ checked Sep 19, 2026	51-200	65 contacts →
	Indirect evidence “Resurety is the only clean energy industry partner to bring together actionable market insights and groundbreaking transaction tools in one seamless ecosystem.” Source: RevenueBase Database · checked Sep 19, 2026
22	Common Energy	Indirect evidence	New York, NY, United StatesHQ checked Sep 19, 2026	11-50	65 contacts →
	Indirect evidence “Common Energy works with developers across the country to activate their clean energy projects and maximize ROI.” Source: RevenueBase Database · checked Sep 19, 2026
23	Basistech	Indirect evidence	Somerville, MA, United StatesHQ checked Sep 19, 2026	51-200	58 contacts →
	Indirect evidence “We work with entrepreneurs to refine ideas, attract talent, access capital, and accelerate growth.” Source: RevenueBase Database · checked Sep 19, 2026
24	Solstice	Indirect evidence	Cambridge, MA, United StatesHQ checked Sep 19, 2026	11-50	56 contacts →
	Indirect evidence “Solstice is dedicated to bringing the benefits of clean energy to every community.” Source: RevenueBase Database · checked Sep 19, 2026
25	Sealed	Indirect evidence	New York, NY, United StatesHQ checked Sep 19, 2026	51-200	54 contacts →
	Indirect evidence “Sealed is a climate tech company on a mission to stop home energy waste by enabling contractors to install more home weatherization and electrification projects and grow their…” Source: RevenueBase Database · checked Sep 19, 2026

RevenueBase Smart Search

RevenueBase Smart Search assesses information from a company’s LinkedIn profile, information supplied directly by the company, its website, and other publicly available sources. It uses that information to rate how closely the company relates to this list’s category: cleantech accelerators. Every row carries its rating and the description the rating was read from, so each one can be checked rather than taken on trust.

Strong evidence: The company's own public description of its business names cleantech accelerators.
Partial evidence: Its own public description names part of cleantech accelerators, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name cleantech accelerators. The match rests on the rest of the company's public profile rather than the one sentence quoted here, so this is the rating to check first.

RevenueBase Smart Search is how these lists are built: RevenueBase's data engine and AI assemble the companies that match a category defined in a user's own words, so a list can be about what companies actually do rather than about whichever industry code they were filed under.

Showing 25 of 818 cleantech accelerators based in the United States

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Cleantech accelerators based in the United States at a glance

As of Sep 19, 2026

24.2%Verified-email coverage

14.3Average contacts per company

1-10Median size (employees)

7.1%Largest-city concentration · New York

Sep 19, 2026Page data refreshed

Companies by employee count

1-10

561

11-50

205

51-200

201-500

501-1,000

5,001-10,000

10001+

Email recency for this list is measured worldwide rather than for United States, so it is reported there. Company counts and contact totals on this page are exact for United States, over 818 companies.

How this list was built

Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among cleantech accelerators, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.

Source: The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
What qualifies: Companies headquartered in the United States whose own description of what they do matches “cleantech accelerators”. Matching reads each company's description, not its industry code or its name.
RevenueBase Smart Search: RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names cleantech accelerators), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
What we exclude: Companies whose own description does not clearly place them among cleantech accelerators, and records with no verified work email. Companies headquartered outside United States are excluded even when they keep an office there.
Match quality: In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
Ranking: Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
Verification: Every listed company carries at least one verified work email, 2,828 across the full list. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
Refresh: This page's figures were pulled from the company graph on September 19, 2026. Lists refresh periodically as the graph is re-checked.
Corrections: Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.

Cleantech accelerators by metro

Frequently asked

What is RevenueBase Smart Search?

RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names cleantech accelerators, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.

How many cleantech accelerators are there based in the United States?

RevenueBase identified 818 cleantech accelerators headquartered in the United States as of September 2026, matched on each company's own description of what it does rather than its industry code.

What is the largest company on this list?

Techstars, headquartered in New York City, tops this list with the largest team on record.

Which city has the most cleantech accelerators?

New York leads with 58 headquartered companies, followed by San Francisco (54) and Houston (36).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 2,828 verified decision-maker contacts tracked across these 818 companies.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 19, 2026.

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About this data

RevenueBase is a B2B data infrastructure company. Its company graph covers 60 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph with RevenueBase Smart Search, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.