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PLACEHOLDERNot a representation of the product
Performance & Value

eVault MAX 18.5

18.43 kWh · LFP · DC-coupled

Fortress PowerReleased 2021

67/ 100

Very good

Global

LFP100% Usable

The verdict. In our Performance & Value class, Fortress Power eVault MAX 18.5 leads on capacity & usability. Home-battery reliability is rarely independently verified, so judge on chemistry, safety certification and the backing company.

16thof 63 in Performance & ValueTop quarterclass average 63.0
Compare this battery →Ask Watt →

The assessment

How it scores, by category

Capacity & Usability90
Power & Efficiency59
Longevity (verified)65
Safety & Chemistry66
Guarantee & Backbone64
Energy Ecosystem64

Market position

16thof 63 in Performance & ValueTop quarter
486776

Our reading

eVault MAX 18.5 scores 67, placing 17 of 63 in the Performance & Value class against a class average of 63.0. Its strongest scoring dimension is capacity & usability (90), running 7.3 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 65. Key specifications: LFP, 9.2 kW continuous output.

The data

Chemistry
LFP
Power
9.2kW
Round-trip
Not recorded
Cycle life
8,000cycles
Technology architecture

DC-coupled battery

Architecture guide

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
Architecture describes the product boundary. It is not a system design or an equipment-pairing decision.

Usable capacity

100% of this battery’s nominal capacity is usable, 18.43 kWh in the scored configuration.

18.43 kWh usableScored configuration: eVault MAX 18.5 single cabinet.

No reserve is withheld at the stated depth of discharge.

At a sourced 100% depth of discharge the usable and nominal figures are the same number, so no separate nominal capacity is stated.

Usable capacity sourceDepth-of-discharge source

Blackout protection

58 / 100#56 of 78 batteries
fleet low 40median 65fleet high 100
No backupGrid-forming

Whole-home (via hybrid inverter)

Continuous power
9.2kW
Switchover
>100ms / undisclosed
AC terminal protection
Not specified

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.

Before you buy
Local positionUse a market view to check local availability, approvals and warranty scope.
Ask the installerWhat usable capacity, backup power and warranted operating conditions will the installed eVault MAX 18.5 configuration deliver?

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 2026-08-05

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.

Record revision. eVault Max datasheet as modified 17 July 2026, warranty effective 1 February 2022, installation manual current edition

Change ledger

Product record history

17 changes to this record · 78 products changed in this update
  1. Evidence added

    Confidence

    Before
    Not previously recorded
    After
    high
    Primary datasheet
  2. Evidence added

    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.
    Primary datasheet
  3. Evidence added

    State

    Before
    Not previously recorded
    After
    supported
    Primary datasheet
  4. Evidence added

    State

    Before
    Not previously recorded
    After
    reviewed_absence
    Primary datasheet
  5. Evidence added

    Confidence

    Before
    Not previously recorded
    After
    high
    Primary datasheet
  6. Evidence added

    Evidence sources

    Before
    Not previously recorded
    After
    https://www.fortresspower.com/download/894/evault-max/47916/fortress-power-evault-max-data-sheet-english.pdf
    Primary datasheet
  7. Evidence added

    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.
    Primary datasheet
  8. Evidence removed

    Round-trip efficiency (%): Evidence status

    Before
    sourced
    After
    No longer recorded
    Primary datasheet
  9. Evidence added

    Evidence sources

    Before
    Not previously recorded
    After
    https://www.fortresspower.com/download/894/evault-max/47916/fortress-power-evault-max-data-sheet-english.pdf
    Primary datasheet
  10. Evidence added

    State

    Before
    Not previously recorded
    After
    supported
    Primary datasheet
  11. Evidence removed

    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
    Primary datasheet
  12. Record updated

    Global score

    Before
    70.6
    After
    66.9
    Primary datasheet
  13. Evidence added

    Confidence

    Before
    Not previously recorded
    After
    high
    Primary datasheet
  14. Record updated

    Power & Efficiency pillar score

    Before
    81.5
    After
    58.7
    Primary datasheet
  15. Evidence added

    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.
    Primary datasheet
  16. Evidence removed

    Round-trip efficiency (%)

    Before
    98
    After
    No longer recorded
    Primary datasheet
  17. Evidence added

    Evidence sources

    Before
    Not previously recorded
    After
    https://www.fortresspower.com/download/894/evault-max/47916/fortress-power-evault-max-data-sheet-english.pdf
    Primary datasheet

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.

  1. Core scorecard evidence checked
  2. US market evidence checked
  3. Series benchmark evidence checked

Evidence record (JSON)

Scored by Solar Analytica Research

Further reading from Findings

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