2023 CTO Accelerator

Application Deadline: April 16th, 2023!

Apply Now!

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 19 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. with 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 $2B in external funding. Join this exciting community and be a part of our global network of innovation.

The application period is now OPEN as of January 3rd, and will remain open until 11:59 PM PT on Sunday 4/16/2023!

Interested in becoming involved in Cleantech Open, or want to let us know your interest in applying for next year? Fill Out This Form and we will get in touch with you soon!

See the National Academy Event Site!

CLICK HERE to see the National Academy Event Site which launched this year's Cohort on June 1st-3rd

CLICK HERE to see the List of 91 Companies in the 2022 Cohort

Recent Events:

    Recruiting Webinar #3 - Click Here to view the recording

Why Apply

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, boot camps, and webinars to launch your startup to the next level.
  • Prizes: In 2023, 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 $150,000 in total cash prizes and/or investment to winners of our regional and national showcasing competitions in the U.S.
    • Up to $50,000 of in-kind 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: ongoing engagement for teams who’ve completed Cleantech Open, including introductions to investors and corporate partners, participation in Challenges, and 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!

*All awards are subject to change at Cleantech Open’s sole discretion and may vary from region to region. The cash component of each award may be provided as a grant or as seed capital (investment). The grand prize is provided as a SAFE note.

How to Apply

1. Step One: Start your startup's profile & registration.

Create a startup profile using the Complete Application Button. Choose the "Startup Registration" option on the left-hand side of the screen.

2. Step Two: Start your application.

Click the “Complete Application” Button from your dashboard after your profile has been submitted. Note that if you would like to preview the application questions and begin working on the application BEFORE submitting your payment, a downloadable version of the application is available HERE. 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 FAQ section below. 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. 

3. Step Three: Complete your application.

You can continue to work on your application UNTIL you submit it. Once it is submitted it moves directly into the judging queue and cannot be modified. 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!

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

You will be prompted to pay the application fee after you finish filling out the application itself but before you can successfully submit it for judging.

5. Step Five: Receive judging feedback and acceptance decision.

After the final deadline of April 16th, you can expect to hear back from us by May 5th about whether or not you were accepted into the Accelerator.

Dates and Fees

Application Deadline and Fee

The application period is open until 11:59 PM PST on April 16th. If you are interested in our next cohort or want to speak with someone about how your product/technology/service aligns with Cleantech Open, please sned an email to

The Application Fee per company is $30 THROUGH February 28th. On March 1st, the application fee becomes $75.

*To qualify as a student, the team must have a full-time student as the Team Lead.

Participation Fee

If you are accepted into the program, the fee for participation in the Cleantech Open is $1,500 for up to two members participating per company (or $1,000 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) 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? Please view the FAQs tab. 

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 participate in the Cleantech Open events over the program year, including the National Academy (East or West)m Business Clinics, Workshops, Networking events, Regional Awards & Innovation Showcase, and our Global Forum. 
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. Travel and accommodation costs are at the expense of the participating company and its members. For the 2023 Program, the National Academies are scheduled in Los Angeles (June 2-4) and Boston (June 6-7). You attend one. Global Forum is in San Jose, CA October 23-26, 2023.

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 (East or West determined) 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.

Judging Criteria

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, credible, and diverse? 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?


What qualifies as a student-led company?

To qualify as a student-led company, the company must have a full-time student as the lead for the Accelerator.

What if I plan to raise a round of funding while participating in the Accelerator? Am I still eligible?

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

Should my technology be at a certain stage of development before I apply?

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 are most useful for companies who are still doing Customer Discovery, creating their Business Models, and forming their products.

Do I need an already established company to apply to the Accelerator?

No - you can be a team of at least two individuals or a company (eg corporation or LLC), although 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 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).

Does my company need to be a US legal entity to apply to the Accelerator?

No. However, a US legal entity (corporation, LLC, or similar) or Canadian / Mexican equivalent must be established before receiving any prizes (we can't write checks to individuals). Any such legal entity must have an ownership structure typical of an independent startup. An IRS Form W-9 or W-8 will be required. For companies outside of North America, check out our Global Ideas page from our 2022 Global Forum, we will be doing a different yet similar program this year. For more info on the Global Ideas program for 2023, please email

Do you offer fee waivers or refunds for the application fee.

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.

What if you only have one company member?

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 or CoFoundersLab to find other entrepreneurs, or try to enlist an advisor/mentor from outside Cleantech Open to join your team

What is the time commitment like?

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 taking time out of it.

Alumni have said they spend about 10 hours per week on Cleantech Open-related activities at any given point during the accelerator. Participation is required in the National Academy (West in Los Angeles, June 2nd-4th and East in Boston, June 6th-7th) and Global Forum (in late October) events are typically 2-3 days in conjunction with a weekend day.

Cleantech Open is for very early stage companies. We're really focused on finding customers right now, and we're concerned Cleantech Open will be a distraction. Should we still apply?

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 require 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.

What if we think we are too early-stage for the Cleantech Open Accelerator?

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.

What if I don't have time to focus on anything besides growing my business?

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 a handful of full-time staff 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 a passive program of lessons.

Cleantech Open is a structured, in-depth, and COMMUNITY-DRIVEN process where we expect you to come out with a stronger and more primed company on the other end. The core of the program can take as little as 10 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.

I'm not sure I want to spend the money (participation fee) if I'm accepted. What should I do?

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.

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, and the millions in funding that are raised by our startups all come because of the massive investment in time and expertise of our community.

What is the acceptance rate?

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.

How long does it take to complete an application?

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.

How long does the Accelerator run?

Five months, with the three months in the middle being the most intense.

Applicants will hear back from Cleantech Open by May 5th whether or not they have been selected to participate in the accelerator. 

The National Academy in June is the official starting point of the accelerator. Regional Finals happen in September. Nationally, the Accelerator ends at the Global Forum with the National Finals Judging, Showcase Expo, Investor & Partner Connect, and an Awards ceremony in late October.

What is a SAFE note?

As in past years, Cleantech Open awards the prize to the US National Winner as an investment in the company, and on very favorable terms to the entrepreneur. This was described in the application when you signed up for the program.

CTO has adopted the SAFE Note (Simple Agreement for Future Equity), which is a standard document created by the Y Combinator accelerator, revised in 2018, and widely used throughout the startup ecosystem. You can read more about it here.

Our intention is that the SAFE is the easiest, simplest, and most entrepreneur-friendly way to provide this prize, and it’s compatible with many other forms of fundraising your company may do.

CTO uses the "Discount, No Cap" version, unmodified from the Y Combinator site. For our prize, CTO uses a “0% discount”, meaning there is no discounted pricing owed to CTO at your next round of financing. In addition, unlike typical convertible notes, there is no interest rate, no capped valuation, no expiration, and no expectation of many other rights, for example, board seats. All these terms are more favorable to you, the entrepreneur than typical investors would accept.

CTO encourages the US National Winner to review this SAFE note with their legal counsel and Board of Directors.