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| Counterparty | Structure | Capacity | Status + Verification | |
|---|---|---|---|---|
| Microsoft | 10-year fixed-price PPA (May 2023) | At least 50 MW | BINDING; signed PPA terms; first commercial fusion PPA globally. Now anchored to Orion, Helion's first commercial plant, where site work began mid-2025 with delivery targeted 2028 to 2029 | |
| Microsoft expansion (announced framework) | Framework MoU for additional capacity beyond initial 50 MW | Up to 1 GW capacity potential | MoU level only; binding terms not yet executed; flagged unverified in FIA report | |
| Nucor (steel manufacturer) | Strategic partnership announced 2024; data-center-adjacent + steel-process applications | Capacity not disclosed | Partnership level; not yet PPA structure; FIA report flags as unverified pending primary source confirmation | |
| Constellation Energy (utility) | Power marketer for the Microsoft PPA | Tied to the Microsoft 50 MW commitment | Role now defined: Constellation serves as power marketer for the Helion-Microsoft arrangement, a firmer structure than the 2024 partnership-level announcement | |
| Sumitomo (Japan) | Strategic investment + partnership; Asia market development | N/A (commercial structure) | Investor + strategic partner; verified primary source | |
| OpenAI + Sam Altman | Investor relationship (Series E + ongoing) | N/A | Verified primary source; Altman is Helion chair | |
| Mithril Capital + SoftBank | Series E + F lead investors | N/A (capital deployment) | Verified primary source | |
| Editorial. Why this matters | Strategic context | Helion has the most public commercial counterparty list of any fusion company. The Microsoft PPA is the marquee binding commitment + the highest-risk delivery schedule in commercial fusion. Marquee question: as Polaris approaches the 2028 net-electricity demonstration window, do Nucor + Constellation + Microsoft-expansion convert from MoU to binding PPA, validating Helion's broader commercial-fusion narrative + de-risking the equity story? |
| Milestone | Original Target | Current Target | Status + Risk | |
|---|---|---|---|---|
| Polaris mechanical completion (7th-gen device) | 2024-Q4 (per Series E 2021 announcement) | 2025-Q2 to Q3 | Mechanical assembly continuing; modest slip vs original | |
| Polaris first plasma | 2025-Q2 (per original schedule) | Achieved | Commissioning complete; machine operating | |
| Polaris fusion demonstration (150M degrees C, D-T) | n/a (new milestone) | Achieved Feb 2026 | Reached ~150 million degrees C; first privately developed machine to demonstrate measurable deuterium-tritium fusion | |
| Polaris D-He3 plasma demonstration | 2026-Q2 (per original schedule) | 2026-Q4 to 2027-Q1 | Pre-electricity scientific demonstration; D-T run is a stepping stone to the aneutronic D-He3 cycle | |
| Polaris net-electricity demonstration | 2027-Q4 (per Series E 2021 announcement) | 2028-Q2 to Q3 | Microsoft PPA delivery target = 2028 calendar year | |
| Microsoft 50 MW PPA delivery start | 2028 (binding PPA terms) | 2028 (Microsoft has not announced renegotiation) | Highest-risk schedule in commercial fusion; modest 6-12 month slip vs original now baked in | |
| Series E funding round closed (Nov 2021) | $500M base + $1.7B contingent on milestones | Complete | Sam Altman, Mithril, SoftBank Vision Fund | |
| Series F funding round closed (mid-2024) | $425M (post-money valuation ~$5.4B) | Complete | Mithril, SoftBank, plus growth-stage tech investors | |
| 2026 funding round | $465M | Complete (2026) | Post-money valuation about $15.5B, roughly 3x the Series F mark | |
| Orion first commercial plant (Malaga WA) | n/a (new milestone) | Site work began mid-2025 | Helion's first commercial plant; 50 MW to Microsoft targeted 2028 to 2029 | |
| Constellation Energy partnership | Announced 2024; status unverified per FIA report | Active partnership; PPA status not binding | Flagged as unverified in sector chart nu-fusion-ppa-pipeline | |
| Nucor partnership (data center power) | Announced; status unverified per FIA report | Active partnership; PPA status not binding | Flagged as unverified in sector chart | |
| Editorial. Why this matters | Strategic context | Helion is the most aggressive commercial-fusion timeline in the industry + holds the only binding PPA (Microsoft 50 MW 2028). The 2-year cushion between Polaris D-He3 demo (2027) + Microsoft PPA delivery (2028) is extremely tight by fusion industry standards. Marquee question: does Polaris demonstrate net-electricity in time to honor the Microsoft PPA, or does the schedule slip force a renegotiation + cascade to other counterparties? |
