We are the cleantech experts.

We find, fund, and foster the most promising cleantech startups on the planet.


Cleantech Open is the world’s largest cleantech accelerator, providing entrepreneurs and corporate innovators the resources they need to launch and grow successful cleantech businesses. Our one-of-a-kind innovation ecosystem built over the last 10 years of programming spans key cleantech innovation hubs in the U.S., linking labs and universities, service providers, investors, corporations, governments, and other cleantech incubators and accelerators. Through our annual accelerator, we provide between 100-150 companies in the U.S. a rich program of customer discovery, extensive mentoring, training, investor meetings, startup-corporate matching, and showcasing at both the regional and national levels. Since 2005, more than 70% of our reporting U.S. alumni companies are still operating and have collectively raised over $1.2B in external funding. Join this exciting community and be a part of our global network of innovation.


Accepted applicants to the program work with mentors, access a valuable network of professionals, and attend business clinics and webinars that provide them with the skills they need to take their business forward. In the fall, teams present their ideas for regional-level judging and are awarded prizes on the regional level. Finalist teams from regions across the country move on to be showcased in our annual Global Forum. The Global Forum showcase also features a competition among the regional winners where national prizes are awarded. If you are interested in applying to the accelerator program, please get started here.

Volunteers and Mentors

As a non-profit organization with a small full-time staff, Cleantech Open is run largely by volunteers. Our volunteers are united in their passion for clean technology and helping to make a difference in the world. If you are interested in volunteering or mentoring a team, please get started here.



Cleantech Open provides tangible benefits:

  • World-class mentoring: receive intensive, tailored mentoring from experienced business experts and gain access to one of the world's only cleantech-specific expert networks.
  • Hands-on training: 12-week series of intensive workshops, bootcamps and webinars to launch your startup to the next level.
  • Prizes: In 2018, U.S. Cleantech Open plans to award a mix of cash and in-kind services to the winners of its showcasing events. This includes:
    • Up to $75,000 in cash prizes to winners of our regional and national showcasing competitions in the U.S.
    • Up to $50,000 of in-kind services - each cash/investment award will be matched with up to an equal amount in services.
    • The opportunity to win more prizes as they are announced.
  • Networking: connect to a powerful national network of influencers and entrepreneurs.
  • Visibility: showcase your startup to investors, strategic partners, and customers through specialized connection events as well as through social media and press releases.
  • Alumni: on-going engagement for teams who’ve completed Cleantech Open, including introductions to investors and corporate partners, participation in Challenges, networking events.

As with most endeavors, what you get out of Cleantech Open is based on the effort and intensity of what you put in.  Don’t expect to simply sign up and expect to win a prize!

*Subject to available funding

Step One: Register as a user.

Click here to register.

Step Two: Complete a startup profile or join an existing team.

After registration, get started by clicking on the “Apply" or visit your Startup Dashboard to submit a new startup profile. At this point, you have the option to create a new startup profile, or join an existing startup. Please only join an existing startup if you are already a part of that team. Your startup profile will not be displayed publicly until the accelerator begins in May.

Step Three: Pay your application fee.

After creating your startup profile, click on the “Apply" button, or visit your Startup Dashboard and click “Submit". You will be prompted to pay the application fee after you start filling out the application itself but before you can successfully submit it for judging. Please see the Dates and Fees section below for more details. Note that if you would like to preview the application questions and begin working on the application BEFORE submitting your payment, we have provided a downloadable version of the application in the Application Toolkit section below.

Step Four: Submit your completed application before the final deadline.

You can continue to work on your application UNTIL you submit it or or up UNTIL Tuesday, April 10th.  We recommend asking our team any application questions as early as possible, attending our Q&A sessions, and getting a mentor or advisor to review the application as early as possible to avoid a last-minute submission.  The earlier you submit your application the better!

Please complete the application by visiting your Startup Dashboard, opening up your application, and clicking “Preview and Submit' at the bottom of the form. Make sure to review to make sure all of the details are correct, and then press the final “Submit" button at the bottom of the page.

Step Five: Receive judging feedback and acceptance decision.

After the final deadline of April 10th, you can expect to hear back from us by May 19th about whether or not you were accepted into the Accelerator. Regardless of your acceptance decision, our panel of expert judges will review your application and provide you with valuable judging feedback. 

Application Deadline and Fee

The application deadline for the 2018 Accelerator is Tuesday, May 1st.  Most regions consider earlier admission, so we encourage you to apply early.  Please check with the Cleantech Open leaders in your region to understand if early admission applies to you.

The application fee per company is: $150 (regular), $100 (student).

*To qualify as a student, the team must have a full-time student as the Company Leader and at least half the company must be students.

Participation Fee

If you are accepted into the program, the fee for participation in the Cleantech Open is $1,200 for up to two members participating per company (or $950 for student-led companies). This covers several months' worth of training, mentoring, and event participation, including receptions and meals. Travel costs and other expenses will not be reimbursed so plan for these additional costs, as attendance at the National Academy (in California or Boston/New York) and Global Forum are required. 

1) Technology

Your technology must fit into one of these categories.

  • Energy Generation
  • Energy Distribution & Storage
  • Energy Efficiency
  • Chemicals & Advanced Materials
  • Information & Communications Technologies (ICT)
  • Green Building
  • Transportation
  • Agriculture, Water & Waste

Confused about how your technology fits? Read our FAQ

2) Funding

Cleantech Open supports early stage startups.  Most startups in our program have less than $1.5MM in funding from private investors or less than $10MM in funding from family, friends, and grants.  There are exceptions, however, and we encourage you to apply even if your funding levels are higher.  We'll evaluate your fit with the program holistically, considering your company's ability to benefit from the program.

3) Company

You must have at least two members.

4) Location

Much of the value Cleantech Open creates for participating startups is centered around relationships and network connections.  For this reason, it is important for your team to physically participate in the Cleantech Open events over the program year, including the National Academy (East or West), Business Clinics, Workshops, Networking events, Regional Awards & Innovation Showcase, and our Global Forum (now part of Cleantech Week).  Please confirm that you'll be able to participate in our program in this way AS THE NATIONAL ACADEMY AND GLOBAL FORUM ARE REQUIRED EVENTS. 

5) Participation

At least one team member must actively engage with the Accelerator by participating in meetings or events that are part of the program, and by submitting final deliverables before Final Judging. There are only two mandatory events at the National level: 1) the National Academy (you choose East or West) and 2) the Global Forum.  There are several mandatory events at the Regional level: 1) Business Clinics and 2) Regional Showcase.

6) Conflict of Interest

You MAY NOT apply if you are an Accelerator volunteer, judge, expert, advisor, mentor, chair, regional director, or if you are in any other way involved with the organization or operation of the accelerator. Immediate family members of the aforementioned people are also ineligible.

You MAY apply if you are affiliated with the accelerator's sponsors and/or partners, as long as you or a family member are not directly involved in the operation of the Cleantech Open, as above.

If you are accepted as an entrepreneur or company participating in the Cleantech Open Accelerator, individuals involved in the running of the Cleantech Open may advise or mentor you, within the rules of the Accelerator, but such individuals may not take a direct interest in your company (such as an equity stake or a paid position) and may not participate as company members until after the Global Forum in the year of your participation.

For our organization, clean tech has a broad definition and encompasses a lot of different technology categories. In addition, startups who get into our program are often at very diverse stages of development. In other words, there is certainly no 'perfect' candidate for the Accelerator.

When judges look at your application, they will be evaluating your entry on the following criteria:

  • Team Is the company's team promising and credible? Have gaps been identified clearly? Do they seem able to attract additional quality team members?
  • Technology Is the technology potentially disruptive? Does it demonstrate the potential for a sustainable competitive advantage?
  • Market Is the potential market size large enough for sustained business growth, and aligned with the expectations of possible funding sources?



To qualify as a student-led company, the company must have a full-time student as the lead for the Accelerator and at least half the company must be students.

Yes - as long as you fall within the funding guidelines at the time of your application, your startup is still eligible.

No - we accept startups at all stages of development. We have had winning teams who started the program with only a concept and no prototype, and we had winning teams who were already selling a product to customers!

That being said, the curriculum and program of Cleantech Open is most useful for companies who are still doing Customer Discovery, creating their Business Models and forming their products.

No - you can be a team of at least two individuals or a company (eg corporation or LLC), although in order to pay out any prize money at the end of the competition, you would need to be a company and provide a W9 form.

You may form a brand new team in order to apply, but we recommend applying with an existing team (you will get more out of the Accelerator with a team that is already established and has a clear definition of roles).

No. However, a US legal entity (corporation, LLC, or similar) must be created prior to receiving any prizes (we can't write checks to individuals). Any such legal entity must have an ownership structure typical of an independent startup.

No. We don't typically offer fee waivers nor do we refund the application fee.  Please read through all FAQs and ask Cleantech Open HQ for clarification before paying the application fee.

One of our basic requirements is that there needs to be a minimum of two people per company. However, sometimes the second company member doesn't have to participate in the program full-time. Most often, only one company member needs to attend most events.

If you are really pressed for a second company member, check out sites like AngelList.co or  CoFoundersLab to find other entrepreneurs, or try to enlist an advisor/mentor from outside Cleantech Open to join your team.

As with most activities, you will get out of Cleantech Open what you put into it. We've tried to design the program so that it integrates into your schedule rather than takes time out of it.

Alumni have said they spend 2-8 hours per week on Cleantech Open-related activities at any given point during the accelerator. The required National Academy and Global Forum events are typically 2-3 days in conjunction with a weekend day.

We hear frequent concerns on both sides of this issue (see below). Yes, it's true, at its heart this program supports early stage startups, but we actually work with a wide range of companies in different developmental stages. We frequently work with teams that have slugged it out for several years and are in need of a few key connections, some new inspiration, that one big seed opportunity, and some great visibility to get their idea to market.

A big part of our program is focused on finding and speaking with customers:  finding them, learning about their needs and determining how your company and technology can fulfill those needs.  Cleantech Open is about finding the best of the next crop of companies that have put in blood, sweat, and tears and are primed to take advantage of the massive opportunity that our program provides.

We love early stage ideas - many of us take a great personal interest in finding out about these and doing what we can to make them real ventures. Often people are too modest or not sure they're ready to get their idea out there and act on what they have to offer. But if you are just starting up, there is no better way than the Cleantech Open Accelerator to focus on business strategy, with guidance from some of the best professionals in the field! Some of our most successful companies came through the Cleantech Open at a very early stage in their process and are now off and running.

Great - then Cleantech Open is perfect for you because it is all about growing your business! Trust us, no one can understand being busy better than us. In many ways, Cleantech Open is like a startup ourselves, with only TWO full-time staff people year-round! Our volunteers give up a huge chunk of their free time because they care about companies like yours.

Our alumni will tell you that the exercises that they went through in the Cleantech Open were what they would have had to do anyway, just on a structured time frame with guidance from mentors. This is not an academic exercise or passive program of lessons.

Cleantech Open is a structured, in-depth and COMMUNITY-DRIVEN process where we expect you to come out a stronger and more primed company on the other end. The core of the program can take as little as a few hours each week, but you'll find that the accelerator's ongoing intangible benefits reach far beyond that. If you don't put your company out there, you'll miss out on the serendipitous, unexpected connections that can occur as a program participant.

Some of our most successful alumni are repeat applicants! Often, companies apply before they're completely ready, and sometimes companies just don't come across well in their first application attempt. That's why we encourage people to re-apply even if they've been passed over before - please let us know how things have changed and what milestones you've hit.

Cleantech Open is a bargain. We aren't just saying that. We've heard of one-day pitch events charging more than what we charge for a 5-6 month program. If we were to charge you full price for everything we were offering, the cost would be >$10,000 per company. If you come to every event, you will get paid back in food alone.

Our large community of professionals are all contributing their time pro-bono to create value for your startup. By paying a participation fee, you're covering the bare minimum of hard costs that this non-profit organization incurs to run smoothly. The value that's added, the jobs that are created, the millions in funding that are raised by our startups all come because of the massive investment in time and expertise of our community.

About 30-50% of applicants are accepted as participants.

This is not a hard number as it is important to understand that it depends on the quality of applications we receive each year. 

It takes only a few moments to create your user profile - the first step. If you have done grants or other accelerator applications in the past, the Cleantech Open application should be a breeze. Most of your time will be spent editing down to our character limits.

If you are starting from scratch, it will take about 2-5 hours total to complete.

Six to seven months, with three months in the middle being most intense.

Applicants will hear back from Cleantech Open by approximately May 19th whether or not they have been selected to participate in the accelerator. This is the official starting point of the accelerator.

The ending point of the  accelerator is in mid-October at Regional Final Judging and the Innovation Expo and Awards Gala. Nationally, the accelerator ends at the Global Forum (National Final Judging) in October / November.