Hi everyone.

I’ve been looking into this company for a while and wanted to share my insights since I think it’s incredibly undervalued at the moment. The first part of this post is a macro picture discussing VRFBs and making a case for their commercial viability. The second part compares VRFBs to competing technologies and introduces Invinity's history and financials. The third part discusses their global expansion, opportunites, and recent developments. The whole thing ended up quite long and I had to split it into three posts, but I believe it’s worth the read considering the opportunity presented here.

Also, I’ve been told that my writing can appear AI generated, which I choose to take as a compliment. I can only assure you that all of this was hand-typed—em dashes and all.

TL;DR

- As renewable penetration grows, both the market and policymakers are placing increasing importance on long duration energy storage.

- Vanadium redox flow batteries are a BESS technology characterized by decoupled power and energy scaling, infinite cycling, very long lifetime, high EOL value, and high safety. No other BESS technology—either existing or approaching commercialization—beats VRFBs in any of these categories.

- VRFBs have a lower energy efficiency than Li-ion, and they are currently well behind on upfront costs. The latter acts as the main hinderance to their mass commercialization. But the gap is rapidly narrowing, and they are already passing the point where the higher upfront cost is justified by their unique advantages in many use cases.

- The VRFB market is projected to grow at a ~20% CAGR. This growth is expected to be bounded by global vanadium supply, rather than demand.

- Invinity is the 3rd largest VRFB manufacturer by deployed capacity, soon to reach 2nd place and become the largest one outside of China.

- Utilizing increasing production scale and automation, raw material supply deals, and component manufacturing outsourcing, they are achieving rapid cost reduction with their new generation Endurium batteries. Their order book and backlog are commensurably growing.

- They're expanding their global market penetration through new strategic partnerships and MoUs. These include royalty agreements with domestic manufacturers in China and Taiwan, raw material supply agreements from China and the US, and establishment of new domestic production capacity in the UK, Canada, the US, and possibly India (either that or another royalty agreement for the latter).

- They have no debt and a clear cash runway well into 2027. In addition to increasing orders, they're opening new revenue streams from the royalty agreements and their own VRFB project. The UK government owns a direct 19.11% equity stake, and institutional+government ownership is at least 62.6%.

- New government programs worldwide to promote LDES solutions hold the potential to increase their backlog by orders of magnitude. The biggest short-term catalyst is the UK Cap & Floor scheme.

There's a lot of important information to cover beyond these points, so I would recommend taking the time to read the whole thing.

Part 1: Macro Picture

Feel free to skip to the next section if you know what LDES is.

I imagine that everyone reading are aware of the global energy crisis and the frantic drive to develop new energy sources. While nuclear is starting to see some love after decades of suspicion, it’s clear that renewables are the go-to solution for developers and projects seeking clean, affordable, sustainable power, and will remain an integral part of the energy grid for the foreseeable future. This is evidenced by the fact that renewables continued to be the fastest growing energy sources in 2025, in spite of policy headwinds from the US.^(1)

Although its sustainable nature and cheapening costs show promise, renewable energy faces several challenges, the largest of which are Intermittency and Variability. The premise for both is simple: the sun doesn’t shine and the wind doesn’t blow according to our energy needs. Looking at utility solar, peak power demand is during the morning and evening, while peak supply is during midday. This was a major inconvenience when renewable penetration was still small but is now developing into a full-blown crisis. Suppliers are often forced to deliberately curtail their output to avoid overwhelming the grid, incurring massive financial losses, while consumers find themselves paying more as a result. For example, wind projects in the UK are regularly forced to curtail more than 50% of their possible output.^(2)

The solution, of course, is energy storage systems (ESS). Excess power is stored during times of high output and low demand and discharged when the opposite occurs. This is called load shifting. Other uses include peak shaving, wherein the ESS takes on some of the discharge burden during peak generation to optimize efficiency (important for nuclear reactors, too), and frequency matching, wherein the ESS corrects deviations to match the plant’s frequency to that of the grid.

The first two are the most crucial to solving the renewable problem and specifically call for long duration energy storage (LDES). These are ESS built with large enough capacity to contain significant excess energy during low demand and discharge it later on. They are usually categorized as having a discharge duration of 8h+ (though many applications can demand multi-day or even multi-month duration, the latter for seasonal balancing). This is in contrast to the majority ESS deployed today with 4h duration at most. The discharge duration is defined as the ratio E/P between the energy capacity and peak power output.

The rapidly growing demand for LDES is attested to by the sheer number of government-level programs and tenders incentivizing the construction of such projects. I’ll discuss a few of them below in relation to Invinity.

VRFBs

Among the various technologies existing today, battery energy storage solutions (BESS) are receiving particular attention due to their rapid deployment, low footprint, low cost, and high efficiency. Any current conversation on BESS is almost entirely dominated by lithium-ion batteries (LIBs), particularly LFP chemistries, and perhaps sodium-ion batteries in some of the more forward-looking discussions. But buried under the attention of ion batteries is another technology that promises to be even more ideal in certain applications: redox flow batteries (RFBs).

https://imgur.com/a/tmy33oz (A schematic illustration of a VRFB)

The most common form of RFBs is aqueous redox flow batteries (ARFBs). These are comprised of two electrolyte solutions separated by a membrane. The porous electrodes of the circuit are each submerged in their respective electrolyte in the part of the battery known as the stack, while the rest of the liquid is stored in tanks. As the battery charges (or discharges), the electrolyte is pumped through the stack, in which it reacts with the electrodes to give or take away electrons. The membrane is designed to allow a specific ion to move through it while remaining impermeable to the others, and the movements of these charge-carrying ions completes the circuit.

This technology offers several major advantages over ion batteries, the most well-known of which is:

Decoupled scaling: In ion batteries, both the energy and power capacity are proportional to number of electrochemical cells. This means that if one wishes to increase the energy capacity, one has to multiply all the electrochemical hardware in proportion, even if there’s no need to increase the power. This also requires a thorough modification of the entire battery’s design, including auxiliaries, which makes it costly to customize both its power and energy to a specific project’s needs.

On the other hand, in ARFBs the energy capacity is determined by the amount of electrolyte, while the power capacity is governed by the size of the stack. To increase the energy, one only has to get bigger tanks and add more electrolyte, leaving the rest of the components as-is. Flow batteries therefore have the potential to be much more economical in LDES applications that require large energy capacity but not necessarily greater power delivery, especially if the electrolyte is cheap. This is the most commonly discussed advantage of ARFBs.

Currently, the only RFB technology mature enough to begin seeing mass production is that of vanadium redox flow batteries (VRFBs), which have seen commercial deployments since the late 90s. These are followed by hybrids like zinc-bromine flow batteries and all-iron flow batteries, and the promising yet early stage organic flow batteries. VRFBs use vanadium electrolyte in both of their half-cells, while protons are the charge carriers crossing the membrane (see the figure). They are the only ARFB close to commercialization (the rest are hybrids), and offer several distinct advantages:

Safety: Lithium battery fire is one of the worst kinds. It’s impossible to extinguish, can last for days, and continuously emits toxic and explosive gases into the air. LFPs offer significant stability improvements over NMC and NCA, but the risk is still there and is often too large to accept. Utility BESS projects routinely get shot down at the municipal level,^(3-6) as communities fear their severity and worry that the local fire departments are ill-equipped to handle such hazards. Many cities and towns are even banning Li-ion BESS entirely within their jurisdiction^(7-10). Projects involving critical infrastructure or expensive hardware (mines, factories, data centers, military bases, etc.) are also not thrilled about the prospect of a flaming portal to hell opening in the adjacent room.

VRFBs, on the other hand, are non-flammable. There is zero fire risk. Not only does this open market segments that are closed off entirely to lithium, i