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Rounds the session metrics to a reasonable precision #29461

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Rounds the session metrics to a reasonable precision #29461

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548c123
Rounds the session metrics to a reasonable precision
tolot27 Apr 27, 2026
31fe11b
address type warning for new()
tolot27 Apr 27, 2026
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27 changes: 22 additions & 5 deletions core/loadpoint_session.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ package core

import (
"errors"
"math"
"time"

"github.com/evcc-io/evcc/api"
Expand All @@ -12,6 +13,20 @@ import (
"github.com/jinzhu/now"
)

func roundFloat64(value float64, digits int) float64 {
factor := math.Pow10(digits)
return math.Round(value*factor) / factor
}

func roundFloat64Ptr(value *float64, digits int) *float64 {
if value == nil {
return nil
}

rounded := roundFloat64(*value, digits)
return &rounded
}

func (lp *Loadpoint) chargeMeterTotal() float64 {
m, ok := api.Cap[api.MeterEnergy](lp.chargeMeter)
if !ok {
Expand Down Expand Up @@ -55,7 +70,9 @@ func (lp *Loadpoint) createSession() {

if lp.site != nil {
lp.session.ReferencePricePerKWh = tariff.AverageRate(lp.site.GetTariff(api.TariffUsageGrid), 24*time.Hour)
lp.session.ReferenceCo2PerKWh = tariff.AverageRate(lp.site.GetTariff(api.TariffUsageCo2), 24*time.Hour)
lp.session.ReferenceCo2PerKWh = roundFloat64Ptr(
tariff.AverageRate(lp.site.GetTariff(api.TariffUsageCo2), 24*time.Hour), 4,
)
}

// energy
Expand All @@ -70,11 +87,11 @@ func (lp *Loadpoint) applyEnergyMetrics(s *session.Session) {
s.MeterStop = &meterStop
}

s.SolarPercentage = new(lp.energyMetrics.SolarPercentage())
s.SolarPercentage = roundFloat64Ptr(new(lp.energyMetrics.SolarPercentage()), 4)
s.Price = lp.energyMetrics.Price()
s.PricePerKWh = lp.energyMetrics.PricePerKWh()
s.Co2PerKWh = lp.energyMetrics.Co2PerKWh()
s.ChargedEnergy = lp.energyMetrics.TotalWh() / 1e3
s.PricePerKWh = roundFloat64Ptr(lp.energyMetrics.PricePerKWh(), 5)
s.Co2PerKWh = roundFloat64Ptr(lp.energyMetrics.Co2PerKWh(), 4)
s.ChargedEnergy = roundFloat64(lp.energyMetrics.TotalWh()/1e3, 5)

lp.db.Persist(s)
}
Expand Down
4 changes: 3 additions & 1 deletion core/session/db.go
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Original file line number Diff line number Diff line change
@@ -1,6 +1,8 @@
package session

import (
"math"

"github.com/evcc-io/evcc/server/db"
"github.com/evcc-io/evcc/util"
"gorm.io/gorm"
Expand Down Expand Up @@ -88,7 +90,7 @@ func (s *DB) ClosePendingSessionsInHistory(chargeMeterTotal float64) error {
}

if session.MeterStart != nil && session.MeterStop != nil {
session.ChargedEnergy = *session.MeterStop - *session.MeterStart
session.ChargedEnergy = math.Round((*session.MeterStop-*session.MeterStart)*1e5) / 1e5
s.Persist(session)
}
Comment on lines 92 to 95
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@sourcery-ai sourcery-ai Bot Apr 27, 2026

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suggestion: Reuse the shared rounding helper instead of duplicating the math here

Since this matches roundFloat64 with digits = 5, please call roundFloat64(*session.MeterStop-*session.MeterStart, 5) instead of inlining the math.Round and 1e5 factor. This keeps rounding behavior consistent with other energy fields and avoids future divergence.

Suggested change
if session.MeterStart != nil && session.MeterStop != nil {
session.ChargedEnergy = *session.MeterStop - *session.MeterStart
session.ChargedEnergy = math.Round((*session.MeterStop-*session.MeterStart)*1e5) / 1e5
s.Persist(session)
}
if session.MeterStart != nil && session.MeterStop != nil {
session.ChargedEnergy = roundFloat64(*session.MeterStop-*session.MeterStart, 5)
s.Persist(session)
}

}
Expand Down
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