How the Symbioen Index works

Four principles

Independence. The index cannot be bought or influenced - and that is precisely where its value comes from. The data behind every score comes exclusively from AFIR-mandated National Access Points: government feeds that operators are legally required to publish.

Driver experience first. The index is not designed to make operators look good. It is designed to measure whether chargers prove service in the public event stream. Every metric - from Availability to Charging Success Rate - is chosen because it catches part of the gap between what an operator reports and what a driver encounters at the charger.

Integrity. Every number is traceable to a raw charger event. The same methodology applies to every operator, at every station, at every level of aggregation - country, region, operator, station, EVSE. One methodology, applied uniformly, verified algorithmically.

Regulatory alignment. Definitions of uptime, availability, and reliability are still settling across the industry. When consensus forms or new regulatory standards take hold, Symbioen updates the methodology accordingly. The methodology is continuously refined to better reflect real-world conditions - and stakeholders are kept informed of any changes as they happen.

The problem with Uptime

The standard metric in EV charging is uptime: the share of time a charger is not in a fault state. Operators publish it. Tenders require it. Investors use it in due diligence. The problem is that self-reported uptime often looks better than the charging experience. Independent field studies have found much lower first-attempt charge success than the 95-99% uptime figures commonly used in marketing, tenders, and data rooms.

The gap is structural. A charger can report Available at the moment a driver arrives, fail to start a session, and still look healthy in a simple uptime report. The charger was, by a narrow status definition, up. From the driver's perspective it was broken.

Where the data comes from

Symbioen data comes from National Access Points - government-mandated feeds that operators are legally required to publish under the EU's AFIR regulation. The public index uses status-event history. Session logs, meter values, and vehicle-side telemetry can improve confidence later, but they are not required for the public score.

What the index measures

The current Symbioen Index is computed at EVSE level first, then aggregated to station, operator, municipality, county, and country levels.

The index combines five core signals. Availability is the uptime component of the model: the share of observed time when the EVSE appears operational and reachable in the status feed. It is important, but it is not the whole score. A clean-looking charger still needs to prove recovery and charging success.

Signal Quality

Signal Quality measures whether the event stream itself can be trusted: duplicate timestamps, impossible ping-pong status patterns, and suppressed update storms all reduce confidence. A charger that is noisy in the feed is often noisy in operation.

Device Reliability

Device Reliability measures what the equipment does as hardware. It looks at failure frequency and short working blocks that suggest oscillation, restart loops, or unstable connectivity. One input is MTBF - mean time between failures: how long the EVSE typically runs before the next observed problem. Short transient reconnect noise is filtered so that brief blips do not incorrectly count as hardware failure.

Operational Responsiveness

Operational Responsiveness measures how quickly and credibly a charger recovers after problems. One input is MTTR - mean time to recovery: how long it takes the EVSE to return from an observed problem to a credible working state. It combines repair speed with post-failure recovery proof: a charger that returns to Available but never proves a charging session remains less credible than one that fails, recovers, and then delivers service.

Charging Success Rate

Charging Success Rate is inferred from status-history transitions into charging or in-use states. A detected session is considered successful when it lasts at least two minutes. A failed short session that is followed by a successful retry within thirty minutes receives partial credit. If no successful sessions are detected, this component contributes zero rather than redistributing its weight: an unproven charger should not score as if it has proved real service.

Availability

Availability is Symbioen's uptime component. It measures the share of observed covered time when the EVSE appears operational and reachable in the status feed. A charger that is technically stable but routinely offline or unreachable is not serving drivers, so this component stays central.

Utilization Rate

Utilization Rate tracks the time a charger spends in active charging use. In practice, it is the strongest public-data confirmation that a charger really works: someone arrived, connected, and the charger entered an active charging state. Low utilization alone does not prove a technical fault; it can also reflect demand, location, or route patterns.

How the index is composed

Symbioen Index brings together the components above into a single score, covering the major failure modes visible in public event data: bad signal quality, hardware instability, slow or unproven recovery, failed charging sessions, and outright unavailability.

The index is calculated at the level of the individual EVSE. The result is a single score per EVSE, ranging from 0 to 100.

Station scoring is not a simple average. Symbioen first estimates station reliability from all eligible EVSE scores, then combines that with the average EVSE score and the weakest EVSE score. The weakest charger matters because one persistently broken connector still damages the user experience.

Operator, municipality, county, and country scores follow the same logic - each level aggregates the level below it, weighted by EVSE count. The result is a consistent set of numbers across every granularity: you can compare a single charger against its station, its station against its operator, and its operator against the national average, all on the same scale and calculated by the same method.

Cleaning the data before scoring

Raw status feeds from National Access Points are not clean. Chargers generate duplicate events, rapid oscillations between states, and brief apparent recoveries that are immediately followed by another failure. Scoring these events naively would reward chargers for a five-second Available signal between two hour-long outages.

Signal Quality catches obvious data-stream issues before they contaminate the score. Duplicate timestamps, impossible status sequences, and repeated flip storms reduce the Signal Quality component. Short offline connectivity blips are filtered where appropriate so transient reconnect noise does not become a false hardware failure.

Broken Episodes are still meaningful. When a charger generates status changes at a rate that indicates a software, hardware, or connectivity problem rather than real state changes, the pipeline suppresses the storm and records that suppression as a scoring signal.

Fair operator rankings

An operator running a single charging point that had a good week should not sit at the top of a national leaderboard above operators running hundreds of stations. Small samples produce unreliable averages - a one-station operator is a coin flip, not a data point.

Operator leaderboards use Bayesian averaging to correct for this. Each operator's score is pulled toward the global mean in proportion to how small their sample is. An operator with one station gets pulled significantly; an operator with two hundred stations is barely affected.

All group-level aggregations - across stations, municipalities, or operators - are also weighted by the number of EVSEs in each group rather than counted equally. A station with twenty chargers contributes proportionally more to an operator's average than a station with two.

When a score is not published

Not every EVSE receives a score. A charger needs enough recent signal history to be rated responsibly. A station score is computed from eligible EVSEs only, and station-level eligibility requires sufficient coverage across active EVSEs. Publishing a number where the feed barely notices the charger would be misleading, so Symbioen returns an ineligible result with the reason.