What are the top climate tech startups by revenue today?

The ranking of top startups in the climate tech market by revenue

Below is a table ranking all the companies in this market by their current revenue scale. You can find our methodology at the end of this page.

If you want a deeper understanding of the market and its current dynamics, get our report covering the Climate Tech Market.

What should actually count as a climate tech startup?

For this ranking, we count private, startup-origin companies whose core business is directly tied to clean energy, electrification, decarbonization, climate software or another major climate technology.

That removes companies such as Tesla, BYD, CATL, Vestas and First Solar. They generate far more revenue than almost every company below, but they are established public companies and would swamp a ranking that is supposed to tell us which startups have reached real commercial scale.

The boundary gets harder with companies such as Octopus Energy. Octopus was founded in 2015, remains privately held and grew through the startup ecosystem, yet it now serves millions of customers and generates revenue on the scale of a major utility. We keep it in the broad ranking because it still fits the corporate definition, while making clear that it has already grown well beyond what most people picture when they hear “startup.”

The same logic applies to Enpal, 1KOMMA5° and Tibber. These companies are better described as scale-ups these days, but dropping successful businesses from the ranking simply because they became large would defeat the purpose of asking which startups make the most money.

Which climate tech startup makes the most revenue today?

Octopus Energy is comfortably the largest private startup-origin climate-tech company we found, with £12.4 billion of annual revenue in its latest group reporting.

That scale is unusual even outside climate tech. Octopus reported eight million customers globally alongside the £12.4 billion revenue figure, putting the company in a completely different revenue category from the rest of the private market.

Enpal, the next major name on direct company revenue, generated more than €1.1 billion in 2025. 1KOMMA5° last disclosed close to €520 million for 2024. Tibber's Swedish company reported SEK2.33 billion of 2025 turnover.

So Octopus leads by roughly an order of magnitude over Enpal and by much more over the next group. Part of that gap comes from the business model: selling electricity produces huge top-line revenue because energy spending itself flows through the company.

Company	Best current revenue evidence	Main business	Evidence
Octopus Energy Group	£12.4B annual revenue	Digital energy retail + technology	Annual report
Enpal	>€1.1B 2025 revenue	Home electrification	Company disclosure
1KOMMA5°	~€520M 2024 revenue	Home electrification	Company disclosure
Tibber AB	SEK2.33B 2025 turnover	Digital electricity retail	Filed accounts
Redwood Materials	~$200M 2024 revenue	Battery recycling and materials	CEO / top-tier reporting
Palmetto HASI Holdings	$88.6M 2025 revenue	Residential solar assets	Audited financial statements

Is Octopus Energy really still a startup?

Octopus Energy still qualifies under a broad private-company definition, although calling it a conventional startup today stretches the word pretty far.

The company has reached £12.4 billion in annual revenue, operates internationally and serves eight million customers. Those numbers look much closer to an established utility than to an early-stage venture-backed business.

Its history still matters. Octopus was founded in 2015 around a technology-led approach to retail energy, remains private, and built Kraken internally before expanding the platform to other utilities.

For readers using a stricter definition based on company maturity rather than ownership, Enpal is the cleaner answer to “largest climate tech startup by revenue.” We keep Octopus visible because otherwise the ranking would hide one of the clearest examples of a climate startup growing into a genuinely huge business.

Is Enpal now the biggest pure climate tech startup by revenue?

Enpal is the strongest current candidate once we move past Octopus and focus on companies that still look recognizably like climate-tech scale-ups.

Enpal said its operating subgroup generated more than €1.1 billion in 2025, up 25% from €890 million the previous year. The company also reported its first full year of positive free cash flow.

More recent operating numbers show that growth has continued. Enpal reported preliminary first-half revenue above €600 million and said it was aiming for more than €1.3 billion for the full year.

That gives us something unusually useful in a private-company ranking: a large revenue figure, a clean comparison with the previous year and a newer partial-period datapoint pointing in the same direction.

Enpal has also moved beyond rooftop solar. Batteries, heat pumps, electricity services, smart meters and energy-management products now sit inside a broader home-electrification model. That diversification helps explain how the business got past the €1 billion line while much of the European residential solar market was struggling.

Can 1KOMMA5° catch Enpal?

1KOMMA5° is growing fast enough to stay in the conversation, but its latest annual revenue disclosure still leaves a large gap with Enpal.

The company reported close to €520 million of revenue for 2024, up from around €450 million in 2023. Organic sales rose from €360 million to about €490 million, which shows that acquisitions were only a small part of the increase.

The newer operating signals are stronger than that old annual figure suggests. 1KOMMA5° recorded roughly €105 million of customer orders in a single month during late 2025, the first time it had crossed €100 million. Global heat-pump sales then increased about 113% in 2025.

Heartbeat AI is becoming a more important part of the story too. The company said subscriptions to the platform had tripled after it opened the software to more third-party and existing energy systems, while controllable capacity in its virtual power plant reached one gigawatt.

Orders, subscriptions and virtual-power-plant capacity cannot replace annual revenue in the ranking. They do tell us that using only the €520 million 2024 figure probably understates 1KOMMA5°'s current commercial scale.

How much revenue does Tibber make?

Tibber's Swedish company reported SEK2.33 billion of turnover in 2025, making Tibber one of the larger private climate-tech businesses for which we can see recent filed financial data.

Revenue increased from SEK2.02 billion in 2024. The company also reported positive operating profit, so this is already a substantial operating business rather than a growth story built entirely around fundraising.

Tibber's model matters when comparing it with other climate startups. It sells electricity through a technology-heavy platform built around dynamic pricing, connected devices and energy management. Electricity therefore passes through revenue in a way that subscription software revenue does not.

That makes Tibber difficult to compare directly with Watershed or another pure software startup, but the revenue is still real. For a ranking based on top-line commercial scale, Tibber belongs near the top.

Is Redwood Materials the biggest US climate tech startup by revenue?

Redwood Materials is one of the strongest US candidates, with about $200 million of revenue in 2024 according to reporting based on comments from the company and CEO JB Straubel.

Redwood is a useful case because the revenue already comes from an industrial business rather than a projected future factory. The company collects and processes lithium-ion batteries and manufacturing scrap, recovers valuable materials and sells materials back into the battery supply chain.

Recent reporting says the $200 million came largely from battery-material sales. Redwood has also expanded into cathode production and second-life energy storage, including battery systems aimed at data-center power.

The evidence remains weaker than Enpal's direct annual revenue disclosure or Tibber's filed accounts because Redwood does not publish full financial statements. Still, the $200 million figure has been repeated in top-tier reporting and has a direct company provenance, which gives it substantially more weight than a generic database estimate.

Redwood is therefore one of the clearest examples of a US climate deep-tech company that has already moved from “big funding round” to meaningful industrial revenue.

Who is making real money in climate software?

Climate software has produced several large companies, but public revenue evidence gets much thinner once we move away from energy retailers and hardware-heavy businesses.

Watershed appears to be among the larger independent climate-software startups, although the widely circulated revenue numbers remain third-party estimates rather than audited disclosures. That means we have much less confidence in its exact position than we do for Enpal, Tibber or 1KOMMA5°.

Aurora Solar has the same problem more severely. Third-party revenue estimates have moved sharply from one year to another, making them too unstable for a precise ranking. Aurora clearly operates at meaningful scale and has been used across millions of solar designs, but that operating footprint does not give us a clean current revenue number.

Kraken is the major exception. Before its separation from Octopus Energy, Kraken said it had reached around $500 million of contracted annual revenue and was contracted to serve more than 70 million household and business accounts. That makes Kraken commercially larger than the typical climate-software startup, although contracted annual revenue still needs to stay separate from recognized revenue.

The pattern is clear: climate software can build very valuable businesses, but the biggest disclosed top-line numbers still sit with companies selling electricity, equipment or physical energy services.

Which climate tech startups have crossed $100 million in revenue?

A surprisingly short list of private climate-tech companies can be placed safely above roughly $100 million using reasonably strong public evidence.

Octopus Energy, Enpal, 1KOMMA5°, Tibber and Redwood Materials all clear the threshold on the evidence we found. Kraken clears it comfortably if we use contracted annual revenue, while keeping that metric separate from recognized sales.

After those companies, confidence falls quickly. Some startups probably generate more than $100 million but do not disclose the figure. Others have large bookings, GMV, customer counts or deployment numbers that cannot be turned into revenue without assumptions.

Climate tech is full of companies that look enormous from their funding, factories or signed contracts. Far fewer have publicly demonstrated nine-figure annual operating revenue.

Does Kraken belong in the climate tech startup revenue ranking now?

Kraken deserves its own place in the climate-tech revenue discussion now that Octopus is spinning the platform out as a standalone company.

Kraken disclosed around $500 million of contracted annual revenue when the separation was announced. The platform was also contracted to serve more than 70 million household and business accounts worldwide.

Those are huge numbers for climate software. The metric needs a clear label, though: contracted annual revenue tells us the annualized value of signed business, while recognized revenue tells us what has actually been recorded in a financial period.

Octopus's annual reporting gives us another useful anchor. Before the separation, recurring licensing revenue from non-Octopus clients was already substantial, while contracted revenue sat much higher because newly signed business had yet to flow fully through reported revenue.

Kraken therefore belongs among the largest climate-software companies by commercial scale, but we would keep the $500 million figure in a separate column from normal annual revenue.

Do EV charging startups dominate climate tech revenue?

Private EV charging startups are commercially important, but they do not currently dominate the revenue leaderboard.

Several of the sector's biggest revenue-generating companies have already gone public, including ChargePoint, EVgo, Fastned, Wallbox and Kempower. Once we limit the question to private startups, revenue disclosure gets much thinner.

Monta is a good example. Its latest sustainability reporting shows 247,000 active charge points at the end of 2025, 25.3 million charging sessions during the year and 644 GWh of energy delivered through the platform.

Those figures show that Monta has reached serious operating scale. They still cannot tell us exactly where Monta belongs in a revenue ranking because the company has not published a comparable company-wide top-line number.

The same issue appears across private charging networks. We can often see charge points, sessions, sites or energy throughput long before we see full revenue.

Are battery startups as big as home-energy startups?

Most battery startups still generate less current revenue than the biggest home-electrification companies, with Redwood Materials standing out as the clearest exception.

The difference comes down to commercialization timing. Enpal and 1KOMMA5° can sell solar systems, batteries and heat pumps to households now. A new battery-chemistry company may need years to build factories, qualify products and ramp manufacturing before sales become large.

Form Energy is a good example. The company has attracted huge amounts of capital and is building iron-air battery manufacturing, but management has indicated that meaningful revenue is only starting as commercial projects begin to arrive.

Base Power has already installed tens of thousands of residential batteries and is expanding rapidly, yet we still do not have a sufficiently strong current revenue disclosure to put it beside Enpal or Redwood.

This is why battery startups can look gigantic in funding rankings and much smaller in revenue rankings. The capital arrives before the factories reach full output.

Why do climate hardware startups look so much bigger than software startups on revenue?

Selling expensive physical systems pushes revenue up very quickly, which is why hardware-heavy climate companies dominate a top-line ranking.

A home-electrification business can sell solar panels, an inverter, a battery, a heat pump, installation and financing in one transaction. A single household can therefore represent tens of thousands of euros of gross sales.

Pure software needs a very different customer count to reach the same number. Even an enterprise platform charging $50,000 a year would need 20,000 customers to reach $1 billion of annual revenue.

That gap helps explain the current ranking. Enpal crossed €1.1 billion by selling physical energy systems and related services. 1KOMMA5° reached roughly €520 million through a similar mix. Tibber gets another top-line boost because electricity purchases flow through its retail model.

Software can still have better gross margins, lower capital needs and stronger recurring economics. Revenue alone does not capture those advantages. For this article, though, revenue is exactly what we are trying to measure.

Does future contracted revenue count as climate tech revenue?

Future contracts are powerful commercial evidence, but we keep them separate from current revenue because the money may be recognized over many years.

Fervo Energy shows why this rule matters. Its SEC filings disclose 658 MW of binding power-purchase agreements and other arrangements representing about $7.2 billion of potential revenue backlog.

That $7.2 billion is extremely meaningful. It shows that utilities and corporate buyers are willing to sign long-term contracts for Fervo's geothermal power.

Most of the value still belongs to future periods. Fervo's filings say the backlog is calculated using expected energy output over the full term of each contract. Treating the whole amount as current revenue would move billions of future sales into the present.

Commonwealth Fusion Systems has a similar example. Eni signed an agreement worth more than $1 billion to buy power from CFS's planned ARC fusion plant. ARC is expected to supply that power in the future, so the contract belongs in a commercial-traction discussion rather than today's revenue column.

These deals matter a lot. They simply answer a different question from “how much revenue does the company make now?”

Are carbon-removal startups already big revenue businesses?

Most carbon-removal startups still look much larger on contracted demand than on current annual revenue.

Direct-air-capture companies can sign long-term removal agreements with major corporate buyers years before the underlying removal capacity is fully operational. The resulting contract values can become very large while recognized annual revenue stays relatively small.

Climeworks is probably the best-known example. The company has operating direct-air-capture plants and major corporate customers, but the public evidence we found does not support placing it anywhere near Enpal, Octopus or 1KOMMA5° on current annual revenue.

That tells us where carbon removal sits today. Customers are willing to pay for future capacity, and the commercial market is real, but most companies are still building the infrastructure required to turn those agreements into large recurring revenue.

Which famous climate tech startups are still much smaller on revenue than people might expect?

Form Energy, Commonwealth Fusion Systems, Climeworks, Base Power and several other heavily funded climate startups are still much smaller on current revenue than their valuations, funding rounds or project announcements might suggest.

Commonwealth Fusion Systems has raised billions and signed a $1 billion-plus power agreement with Eni. That is extraordinary commercial validation for fusion, yet the ARC plant that will supply the electricity is still a future project.

Form Energy has built manufacturing capacity and large project pipelines, but commercial revenue is only beginning to become meaningful. Base Power already has a large residential battery footprint but does not publish enough financial detail for us to place it confidently in the revenue table.

Monta offers another version of the same problem. We know that 247,000 active charge points used its software at the end of 2025, but active charge points are not revenue.

These companies may eventually move very quickly once projects and factories ramp. For now, the most famous names in climate venture capital are often different from the companies already producing the most sales.

What happened to Northvolt in a climate tech revenue ranking?

Northvolt is a warning against using an old revenue figure as if it still described the company today.

Northvolt once looked like one of Europe's strongest candidates to build a giant battery manufacturer. The company raised billions, signed major customer contracts and built factories intended to compete with Asian battery suppliers.

Northvolt filed for bankruptcy in Sweden in 2025 after production problems, financing pressure and difficulties scaling its industrial operations.

That means an older Northvolt revenue number can still tell us something about historical commercial activity, but it should not sit beside operating companies as evidence of present scale.

Revenue rankings need freshness for exactly this reason. A number can be perfectly real and still become useless for answering a question about the market now.

Can a climate startup's valuation tell us how much revenue it makes?

Valuation is a terrible shortcut for climate-tech revenue because different business models receive completely different multiples.

A fusion startup can be valued in the billions before selling commercial electricity. A software company can reach a large valuation on tens of millions of dollars of recurring revenue. An energy retailer can record billions of revenue while keeping relatively thin margins.

Redwood shows the contrast well. The company has reached a multibillion-dollar valuation while its last widely reported revenue figure is around $200 million.

Octopus sits at the opposite end of the revenue-multiple spectrum. Its energy business produces more than £12 billion of annual revenue because customer energy spending flows through the company.

Trying to estimate revenue from valuation would therefore produce absurd results across climate tech. We use actual revenue or clearly labeled commercial metrics instead.

How reliable is this climate tech startup revenue ranking?

The top of the ranking is much more reliable than the middle and bottom because the strongest companies also happen to disclose better financial information.

Octopus has formal group reporting. Enpal publishes detailed annual business updates. 1KOMMA5° directly reports its sales. Tibber has filed local accounts. Palmetto's solar-asset joint venture has audited statements filed with the SEC.

Redwood's $200 million figure sits one level lower because it comes through top-tier reporting and comments from company leadership rather than published company financial statements.

Below that, the picture becomes patchier. Some companies publish ARR. Some give bookings. Others disclose contracts, installed units, customers or network activity. A few have only third-party revenue estimates.

So we have high confidence in the broad hierarchy and lower confidence in exact positions once comparable revenue disappears. Pretending every row has the same evidence quality would make the table cleaner and the analysis worse.

What does the climate tech startup revenue ranking look like now?

The most defensible current ranking starts with Octopus Energy, followed by Enpal, 1KOMMA5° and Tibber, with Redwood Materials leading the next group on the public revenue evidence we found.

The table deliberately separates direct revenue from weaker or structurally different metrics. A company with a giant future contract does not jump ahead of a company already generating hundreds of millions of dollars in sales.

Rank	Company	Best revenue evidence	Metric	Confidence	Segment
1	Octopus Energy Group	£12.4B	Annual revenue	High	Digital energy / utilities
2	Enpal	>€1.1B	2025 revenue	High	Home electrification
3	1KOMMA5°	~€520M	2024 revenue	High	Home electrification
4	Tibber AB	SEK2.33B	2025 turnover	High	Digital energy retail
5	Redwood Materials	~$200M	2024 revenue	Medium	Battery recycling / materials
6	Palmetto HASI Holdings	$88.6M	2025 JV revenue	Medium	Distributed solar assets
—	Kraken	~$500M	Contracted annual revenue	High, different metric	Energy software
—	Monta	247,000 active charge points	Operating scale	High, non-revenue	EV charging software
—	Fervo Energy	~$7.2B potential backlog	Future contracted revenue	High, non-current	Geothermal
—	Commonwealth Fusion Systems	>$1B Eni PPA	Future contracted revenue	High, non-current	Fusion

Why is Palmetto's $88.6 million figure treated cautiously?

Palmetto HASI Holdings gives us excellent financial evidence, but the $88.6 million figure covers a specific solar-asset joint venture rather than the whole Palmetto operating company.

Audited financial statements filed through HA Sustainable Infrastructure show $88.6 million of 2025 revenue, up from $15.4 million in 2024. The revenue comes primarily from residential solar power-purchase agreements and leases.

That is unusually strong evidence for a private climate business because we can see audited financial statements rather than estimates.

The corporate perimeter prevents us from calling it Palmetto's full company revenue. The joint venture owns residential solar and battery projects developed and managed by Palmetto, so its results capture a meaningful slice of the ecosystem without representing every part of the parent business.

We keep the number because it is useful and highly credible, while labeling the scope rather than pretending it covers more than it does.

Where does climate tech revenue actually come from today?

The biggest private climate-tech revenue pools currently come from energy retail, home electrification and physical energy infrastructure rather than the most experimental technologies.

Octopus sells electricity at massive scale. Enpal and 1KOMMA5° sell expensive home-energy systems. Tibber combines electricity retail with software. Redwood sells recycled and manufactured battery materials.

That pattern changes once we look at valuations or funding. Fusion, carbon removal, long-duration storage and advanced geothermal suddenly become much more prominent because investors are paying for future industrial potential.

Revenue gives us a view of what customers are paying for now.

Today, the answer is surprisingly practical: electricity, solar systems, batteries, heat pumps, installations and battery materials are producing much more startup revenue than the technologies that dominate futuristic climate headlines.

So which climate tech startups are actually the biggest by revenue today?

Octopus Energy is the clear revenue leader under a broad private climate-tech definition, while Enpal is the strongest answer for readers who want a company that still looks like a conventional climate-tech scale-up.

Behind Enpal, 1KOMMA5° and Tibber have reached hundreds of millions in annual sales, while Redwood Materials has built a roughly $200 million industrial business from battery recycling and materials.

The ranking also exposes a large gap between commercial hype and current revenue. Fervo has billions in potential contracted revenue, Commonwealth Fusion Systems has a $1 billion-plus future power agreement, and Monta runs software across hundreds of thousands of charge points. Those are serious commercial achievements, but they belong in different columns from recognized annual revenue.

The private companies making the most money right now are generally selling products customers can already buy and use at scale: electricity, solar systems, heat pumps, batteries and industrial materials.

That may change dramatically as geothermal, fusion, carbon removal and new battery technologies reach full commercial operation. For now, climate tech's revenue leaders look much more like energy companies and industrial operators than science-fiction startups.