The assessment
How it scores, by category
Market position
The data
DC-coupled battery
Stores DC energy and relies on system power electronics outside the battery product for household AC.
- Product role
- The published battery record covers the storage stack, controller and stated capacity range.
- Published range
- 18.43 kWh
- Phase
- Not recorded
- Backup boundary
- Installation-specific
Usable capacity
Stated depth of discharge: 100%. Published usable energy: 18.43 kWh in the scored configuration. These values may have different measurement conditions.18.43 kWh usableScored configuration: eVault MAX 18.5 single cabinet.
The stated depth of discharge and published usable energy can have different test conditions or configuration limits. They do not by themselves establish nominal capacity or a reserve that is always inaccessible. Delivered AC energy and runtime also depend on the inverter, settings and loads.
The score is fixed to the single 18.43 kWh cabinet; parallel expansion to 20 cabinets does not change the scored configuration.
Usable capacity sourceDepth-of-discharge sourceBlackout protection
58 / 100#60 of 90 batteriesWhole-home (via hybrid inverter)
The blackout score is a standalone benchmark of outage resilience only - it re-weights sourced specs already scored in this product’s pillars (backup tier, switchover, surge strength, backup power, off-grid recharge) and never affects the overall score. Dots show the full battery fleet; the marker is this product.
Verification & sources
Market context
Global evidencechange in the site menu
Global benchmark. This scorecard is benchmarked globally. A global score does not imply local availability, certification, warranty coverage, or installer compatibility.
Benchmark anchor. The score is fixed to the single 18.43 kWh cabinet; parallel expansion to 20 cabinets does not change the scored configuration. Scored model: eVault MAX 18.5 single cabinet · checked 2026-08-04. Evidence.
Sources & references · checked 2026-09-01
Strong evidence coverage
30 of 30 scored criteria link directly to a published source.
Values marked estimated, derived, or not found remain visible on the audit sheet and do not carry the same evidential weight as a linked source. Coverage measures direct links, not an independent guarantee that a claim is correct.
How far the evidence reaches
- OutputManufacturer claim3 rows in the rings4 design facts beside the rings
- EnduranceManufacturer claim4 rows in the rings3 warranty terms beside the rings
- SafetyCertified or regulator-listed1 of 4 rows in the rings beyond claim1 design fact beside the rings
- BackingManufacturer claim2 rows in the rings1 warranty term beside the rings
- FitManufacturer claim3 rows in the rings5 design facts beside the rings
- FootprintNot assessed for batteries
Rings, outside in: manufacturer claim, certified or regulator-listed, third-party source. The centre is review.solar's own measurement, empty for every product today. Warranty terms and design facts that rest on the maker's own word are counted beside the rings; a reviewed absence, or one that reaches beyond the maker's claim, stays in them. How the evidence puzzle works
Record revision. eVault Max datasheet as modified 17 July 2026, warranty effective 1 February 2022, installation manual current edition. First-market DE overlay review 2026-09-01: official German catalogues recorded; existing Australian and United States overlays and scores unchanged.
- Sourced valuesData card →
- Archived copy of the primary sourcePDF ↗
Show 6 more
- Cell balancing architectureManufacturer ↗
- Safety certificationManufacturer ↗
- Financial strength & warranty backingManufacturer ↗
- Manufacturing track recordManufacturer ↗
- Open protocol & API maturityManufacturer ↗
- VPP & grid services readinessManufacturer ↗
Help strengthen this record
These are published evidence gaps, not private submissions. A source is reviewed under the same methodology whether it comes from a reader, installer or manufacturer.
- End-of-warranty retained capacity (%)Not stated in reviewed documentsThe public documents reviewed for this record do not state this value. A published or independent source is requested.Offer a source
- Cell balancing architectureNot stated in reviewed documentsThe public documents reviewed for this record do not state this value. A published or independent source is requested.Offer a source
- AC terminal & connection protectionNot stated in reviewed documentsThe public documents reviewed for this record do not state this value. A published or independent source is requested.Offer a source
- EV charging integrationNot stated in reviewed documentsThe public documents reviewed for this record do not state this value. A published or independent source is requested.Offer a source
Product record history
1 change to this record · 5 products changed in this update
Safety certification: Evidence sources
- Before
- https://www.fortresspower.com/download/894/evault-max/47916/fortress-power-evault-max-data-sheet-english.pdf
- After
- https://solarequipment.energy.ca.gov/Home/DownloadtoExcel?filename=BatteryList; https://www.fortresspower.com/download/894/evault-max/47916/fortress-power-evault-max-data-sheet-english.pdf
2 changes to this record · 22 products changed in this update
EV charging integration: Evidence sources
- Before
- https://www.fortresspower.com/download/893/envy-true-12/47834/fortress-power-envy-true-12-data-sheet-english.pdf
- After
- https://www.fortresspower.com/download/893/envy-true-12/47834/fortress-power-envy-true-12-data-sheet-english.pdf; https://www.fortresspower.com/download/893/envy-true-12/47837/fortress-power-envy-true-12-installation-manual.pdf; https://www.fortresspower.com/download/894/evault-max/47916/fortress-power-evault-max-data-sheet-english.pdf; https://www.fortresspower.com/download/894/evault-max/47917/fortress-power-evault-max-installation-manual.pdf
Cell balancing architecture: Evidence sources
- Before
- https://www.fortresspower.com/products/evault-max-18-5kwh-lifepo-battery/
- After
- https://www.fortresspower.com/download/894/evault-max/47916/fortress-power-evault-max-data-sheet-english.pdf; https://www.fortresspower.com/download/894/evault-max/47917/fortress-power-evault-max-installation-manual.pdf; https://www.fortresspower.com/products/evault-max-18-5kwh-lifepo-battery/
1 change to this record · 11 products changed in this update
US Certifications
- Current text
- The California Energy Commission Battery List carries model eVaultMax under Fortress Power LLC, described as a 9.2 kW, 18.5 kWh lithium iron phosphate battery, UL 1973 certified by Intertek, with a listing date of 1 September 2021. The same model is on the Energy Storage System List under UL 9540.; The datasheet lists UL1642, UL1973, UL9540 and UL9540A. Fortress publishes its own letter dated 13 June 2022 reporting a UL 9540A large-scale fire test of the eVault MAX and eFlex batteries by TUV Rheinland, with no external flaming observed; the TUV Rheinland report itself is not among the published product downloads. Fortress also publishes Intertek authorizations to mark for UL 1973:2022 Ed.3 (model eVault Max, issued 23 April 2024) and UL 9540:2023 Ed.3 (issued 26 April 2024); the UL 9540 authorization names paired Sol-Ark/eVault MAX and Envy/eVault MAX system models rather than the battery alone. The California Energy Commission record cites older editions, UL 1973 Ed. 2:2018 and UL 9540 Ed. 1:2016, both with a certificate date of 18 June 2021.
The previous text is not reproduced here: both versions run to a full research paragraph. Both are in the JSON record linked below.
US market evidencePrimary datasheet+3 in JSON record
5 changes to this record · 152 products changed in this update
DE Evidence sources
- Before
- Not previously recorded
- After
- https://www.fortresspower.com/de/
Source revision
- Before
- eVault Max datasheet as modified 17 July 2026, warranty effective 1 February 2022, installation manual current edition
- After
- eVault Max datasheet as modified 17 July 2026, warranty effective 1 February 2022, installation manual current edition. First-market DE overlay review 2026-09-01: official German catalogues recorded; existing Australian and United States overlays and scores unchanged.
DE Support Note
- Before
- Not previously recorded
- After
- fortresspower.com/de opens a dealer-application page, not a German product catalogue, and does not name eVault MAX 18.5.
17 changes to this record · 78 products changed in this update
Value
- Before
- Not previously recorded
- After
- The exact datasheet publishes 98% efficiency at 0.5C but does not explicitly define the value as round-trip efficiency.
Evidence sources
- Before
- Not previously recorded
- After
- https://www.fortresspower.com/download/894/evault-max/47916/fortress-power-evault-max-data-sheet-english.pdf
Value
- Before
- Not previously recorded
- After
- Reviewed 2026-08-25: The exact datasheet publishes 98% efficiency at 0.5C but does not explicitly define the value as round-trip efficiency. No battery/DC round-trip value is substituted into the score.
Evidence sources
- Before
- Not previously recorded
- After
- https://www.fortresspower.com/download/894/evault-max/47916/fortress-power-evault-max-data-sheet-english.pdf
Round-trip efficiency (%): Evidence sources
- Before
- https://www.fortresspower.com/download/894/evault-max/47916/fortress-power-evault-max-data-sheet-english.pdf
- After
- No longer recorded
Value
- Before
- Not previously recorded
- After
- Datasheet Cycle Life 8,000 at 80% DoD; the installation manual defines end of cycle life as retained capacity equivalent to 70% of year 1 capacity.
Evidence sources
- Before
- Not previously recorded
- After
- https://www.fortresspower.com/download/894/evault-max/47916/fortress-power-evault-max-data-sheet-english.pdf
This is review.solar's publication history. It does not claim the product changed on the recorded date, and it excludes compatibility, system pairing, installation suitability and relative leaderboard prose. Open the complete JSON record.
Evidence timeline
Recorded verification events for this scorecard. These are evidence checks, not historical score snapshots.
- Core scorecard evidence checked
- DE market evidence checked
- US market evidence checked
- Series benchmark evidence checked
Scored by Solar Analytica Research
Further reading from Findings
Stay across the benchmark.
New scorecards, score changes and market signals, published as they happen.
Our reading
eVault MAX 18.5 scores 67, placing 20 of 76 in the Performance & Value class against a class average of 63.6. Its strongest scoring dimension is capacity & usability (90), running 6.4 points above the class average on this dimension. Power & Efficiency scores 59, the lowest pillar for this product. The class average on power & efficiency is 66. Key specifications: LFP, 9.2 kW continuous output.
Dietreich Farquharson · review.solar