diff --git a/app/src/components/EnergyFlowDiagram.tsx b/app/src/components/EnergyFlowDiagram.tsx
index f2bca2f..8471ec5 100644
--- a/app/src/components/EnergyFlowDiagram.tsx
+++ b/app/src/components/EnergyFlowDiagram.tsx
@@ -131,12 +131,13 @@ export default function EnergyFlowDiagram({ live, className }: EnergyFlowDiagram
   const { t } = useTranslation();
   const uid = useId().replace(/[:]/g, '');
 
-  const fvToHome = Math.min(live.production, live.consumption);
+  const cons = live.consumption ?? 0;
+  const fvToHome = Math.min(live.production, cons);
   const charging = live.batteryPower > 0 ? live.batteryPower : 0;
   const discharging = live.batteryPower < 0 ? -live.batteryPower : 0;
-  const exporting = live.grid < 0 ? -live.grid : 0;
-  const importing = live.grid > 0 ? live.grid : 0;
-  const solarSurplus = Math.max(0, live.production - live.consumption);
+  const exporting = live.grid != null && live.grid < 0 ? -live.grid : 0;
+  const importing = live.grid != null && live.grid > 0 ? live.grid : 0;
+  const solarSurplus = Math.max(0, live.production - cons);
   const gridToBattery = Math.max(0, Math.min(charging - solarSurplus, importing));
   const fvToBattery = Math.max(0, charging - gridToBattery);
 
@@ -165,7 +166,13 @@ export default function EnergyFlowDiagram({ live, className }: EnergyFlowDiagram
         ? `${fmtKw(-live.batteryPower)} kW`
         : t('common.idle');
   const gridText =
-    live.grid < -0.05 ? `${fmtKw(-live.grid)} kW ↑` : live.grid > 0.05 ? `${fmtKw(live.grid)} kW ↓` : '0 W';
+    live.grid === null
+      ? '—'
+      : live.grid < -0.05
+        ? `${fmtKw(-live.grid)} kW ↑`
+        : live.grid > 0.05
+          ? `${fmtKw(live.grid)} kW ↓`
+          : '0 W';
 
   return (
     <motion.svg
@@ -198,8 +205,8 @@ export default function EnergyFlowDiagram({ live, className }: EnergyFlowDiagram
         x={NODES.home.x}
         y={NODES.home.y}
         label={t('flow.home')}
-        valueText={`${fmtKw(live.consumption)} kW`}
-        active={live.consumption > 0.1}
+        valueText={live.consumption === null ? '—' : `${fmtKw(live.consumption)} kW`}
+        active={cons > 0.1}
         glowColor={homeColor}
       >
         <House size={30} style={{ color: homeColor }} />
@@ -227,11 +234,11 @@ export default function EnergyFlowDiagram({ live, className }: EnergyFlowDiagram
         y={NODES.grid.y}
         label={t('common.grid')}
         valueText={gridText}
-        active={Math.abs(live.grid) > 0.1}
-        glowColor={live.grid < 0 ? palette.redVertido : palette.redCompra}
+        active={live.grid != null && Math.abs(live.grid) > 0.1}
+        glowColor={live.grid != null && live.grid < 0 ? palette.redVertido : palette.redCompra}
         onClick={() => navigate('/historico')}
       >
-        <UtilityPole size={26} style={{ color: live.grid < 0 ? palette.redVertido : palette.redCompra }} />
+        <UtilityPole size={26} style={{ color: live.grid != null && live.grid < 0 ? palette.redVertido : palette.redCompra }} />
       </FlowNode>
     </motion.svg>
   );
diff --git a/app/src/components/LivePowerStrip.tsx b/app/src/components/LivePowerStrip.tsx
index 0f9d0c3..5e56543 100644
--- a/app/src/components/LivePowerStrip.tsx
+++ b/app/src/components/LivePowerStrip.tsx
@@ -12,7 +12,8 @@ import { cn } from '@/lib/utils';
 interface StripValueProps {
   icon: LucideIcon;
   label: string;
-  kw: number;
+  /** null = sin dato fiable (medidor caído, issue 135): se muestra '—'. */
+  kw: number | null;
   status?: string;
   color: string;
   /** Color del icono; si se omite, usa `color` (icono y celda iguales). */
@@ -24,7 +25,7 @@ interface StripValueProps {
 }
 
 function StripValue({ icon: Icon, label, kw, status, color, iconColor, className, altValue, altUnit }: StripValueProps) {
-  const animated = useAnimatedNumber(altValue === undefined ? kw : NaN);
+  const animated = useAnimatedNumber(altValue === undefined ? (kw ?? NaN) : NaN);
   return (
     <div className={cn('flex items-center gap-3 px-4 py-3 sm:px-5', className)}>
       <span className="flex h-9 w-9 shrink-0 items-center justify-center rounded-xl" style={{ backgroundColor: `${color}1F`, color: iconColor ?? color }}>
@@ -33,10 +34,10 @@ function StripValue({ icon: Icon, label, kw, status, color, iconColor, className
       <div className="min-w-0">
         <p className="text-[11px] font-medium uppercase tracking-[0.06em] text-faint">{label}</p>
         <p className="font-display text-[22px] font-semibold leading-tight text-app" aria-live="off">
-          {altValue !== undefined ? altValue : fmtKw(animated)}
+          {altValue !== undefined ? altValue : kw === null ? '—' : fmtKw(animated)}
           {altUnit !== undefined ? (
             <span className="ml-1 text-[0.6em] font-medium text-faint">{altUnit}</span>
-          ) : (
+          ) : kw === null ? null : (
             <span className="ml-1 text-[0.6em] font-medium text-faint">kW</span>
           )}
         </p>
@@ -60,14 +61,15 @@ interface LivePowerStripProps {
 export default function LivePowerStrip({ live, atMin }: LivePowerStripProps) {
   const palette = useEnergyColors();
   const { t } = useTranslation();
-  const exporting = live.grid < -0.05;
+  const exporting = live.grid != null && live.grid < -0.05;
 
   const batteryLabel = (bp: number): string => {
     if (bp > 0.05) return t('common.charging');
     if (bp < -0.05) return t('common.discharging');
     return t('common.idle');
   };
-  const gridLabel = (grid: number): string => {
+  const gridLabel = (grid: number | null): string => {
+    if (grid === null) return '—';
     if (grid > 0.05) return t('live.buying');
     if (grid < -0.05) return t('live.exporting');
     return t('live.balanced');
@@ -106,7 +108,7 @@ export default function LivePowerStrip({ live, atMin }: LivePowerStripProps) {
         <StripValue
           icon={exporting ? ArrowUpFromLine : ArrowDownToLine}
           label={t('common.grid')}
-          kw={Math.abs(live.grid)}
+          kw={live.grid === null ? null : Math.abs(live.grid)}
           status={gridLabel(live.grid)}
           color={exporting ? palette.redVertido : palette.redCompra}
           className="border-l border-t border-app lg:border-t-0"
diff --git a/app/src/data/EnergyDataProvider.tsx b/app/src/data/EnergyDataProvider.tsx
index c68ce3a..41c28fb 100644
--- a/app/src/data/EnergyDataProvider.tsx
+++ b/app/src/data/EnergyDataProvider.tsx
@@ -81,8 +81,10 @@ function integrateSeries(series: PowerPoint[], untilMin: number, socFallback: nu
     if (p.t >= untilMin) break;
     productionKwh += p.production * dtH;
     consumptionKwh += p.consumption * dtH;
-    if (p.grid > 0) gridImportKwh += p.grid * dtH;
-    else gridExportKwh += -p.grid * dtH;
+    if (p.grid != null) {
+      if (p.grid > 0) gridImportKwh += p.grid * dtH;
+      else gridExportKwh += -p.grid * dtH;
+    }
     if (p.batteryPower > 0) batteryChargedKwh += p.batteryPower * dtH;
     if (p.batteryPower < 0) batteryDischargedKwh += -p.batteryPower * dtH;
     directFvKwh += Math.min(p.production, p.consumption) * dtH;
diff --git a/app/src/data/types.ts b/app/src/data/types.ts
index 56251c1..3a98e4b 100644
--- a/app/src/data/types.ts
+++ b/app/src/data/types.ts
@@ -8,7 +8,8 @@ export interface PowerPoint {
   consumption: number;
   batteryPower: number;
   soc: number;
-  grid: number;
+  /** null = entradas de la fórmula caídas en ese bucket (issue 135): sin dato fiable. */
+  grid: number | null;
 }
 
 /** Valor de serie de un inversor por clave: p.inverters[key] o p[key] (solis/fox). */
@@ -31,10 +32,12 @@ export interface LiveInverter {
 
 export interface LivePower {
   production: number;
-  consumption: number;
+  /** null = algún medidor de consumo caído (issue 135): consumo no fiable. */
+  consumption: number | null;
   batteryPower: number;
   soc: number;
-  grid: number;
+  /** null = fuente de red caída (issue 135): sin dato de red. */
+  grid: number | null;
   solis: number;
   fox: number;
   inverters?: LiveInverter[];
diff --git a/app/src/lib/format.ts b/app/src/lib/format.ts
index 512d663..b5907b8 100644
--- a/app/src/lib/format.ts
+++ b/app/src/lib/format.ts
@@ -24,8 +24,9 @@ export function fmtPower(kW: number): [string, string] {
   return [nf2().format(kW), 'kW'];
 }
 
-/** Potencia siempre en kW con 2 decimales (para series del día). */
-export function fmtKw(kW: number): string {
+/** Potencia siempre en kW con 2 decimales (para series del día). null = sin dato (medidores caídos). */
+export function fmtKw(kW: number | null | undefined): string {
+  if (kW === null || kW === undefined || !Number.isFinite(kW)) return '—';
   return nf2().format(kW);
 }
 
diff --git a/server/src/solar.js b/server/src/solar.js
index c41c5e2..fe402c7 100644
--- a/server/src/solar.js
+++ b/server/src/solar.js
@@ -83,6 +83,11 @@ export function computeLive(ha) {
     invLive.push({ key: inv.key, name: inv.name, kw: round3(kw) })
   }
   const consumption = consumptionKw(ha)
+  // Medidores de consumo caídos con HAOS conectado (issue 135): el consumo
+  // derivado no es fiable → null + alerta. Un 0 fabricaría exportaciones
+  // imposibles al alimentar la curva del día.
+  const isDown = (e) => e === undefined || e.state === 'unavailable' || e.state === 'unknown'
+  const consDown = ha.connected && (t.consumption.powerIds || []).some((id) => isDown(ha.getState(id)))
 
   const b = t.battery
   const batMag = b.enabled ? entityNum(ha, b.powerId) : 0
@@ -109,18 +114,29 @@ export function computeLive(ha) {
     }
   }
 
+  // Fuente de red caída con HAOS conectado (issue 135): grid → null en vez
+  // de un 0 espurio que los fallbacks convertirían en import/export inventado.
+  const gridDown =
+    ha.connected &&
+    ((t.grid.mode === 'attrs' && t.grid.attrsId && isDown(ha.getState(t.grid.attrsId))) ||
+      (t.grid.mode !== 'attrs' && t.grid.sensorId && isDown(ha.getState(t.grid.sensorId))) ||
+      (t.grid.mode !== 'attrs' &&
+        !t.grid.sensorId &&
+        ((t.grid.importId && isDown(ha.getState(t.grid.importId))) || (t.grid.exportId && isDown(ha.getState(t.grid.exportId))))))
+
   const sun = ha.getState(t.sun)
   const weather = ha.getState(t.weather)
   const elevation = num(sun?.attributes?.elevation)
 
   // Sanity check: de noche sin sol, no puede haber export solar
-  if (elevation < 0 && grid < -0.03 && production < 0.02) grid = -grid
+  if (!gridDown && elevation < 0 && grid < -0.03 && production < 0.02) grid = -grid
 
   // Fallback: si no hay datos de grid pero hay consumo y no hay producción, estimar import
-  if (grid === 0 && consumption > 0.1 && production < 0.02) grid = consumption
+  if (!gridDown && grid === 0 && consumption > 0.1 && production < 0.02) grid = consumption
 
   const alerts = []
   if (!ha.connected) alerts.push({ id: 'haos', severity: 'critical', text: 'Sin conexión con Home Assistant' })
+  if (consDown) alerts.push({ id: 'consumo', severity: 'warning', text: 'Medidores de consumo sin datos' })
 
   // Estado del inversor: desde statusAttrsId (opcional). Si no hay sensor con
   // esos atributos, no hay alerta de inversor/scraper (genérico). Textos sin
@@ -145,13 +161,13 @@ export function computeLive(ha) {
   const inv1 = invLive[1] || { kw: 0 }
   return {
     production: round3(production),
-    consumption: round3(consumption),
+    consumption: consDown ? null : round3(consumption),
     respaldoKw: round3(entityNum(ha, t.consumption.respaldoId, t.consumption.powerUnit === 'W' ? 1000 : 1)),
     noRespaldadaKw: round3(entityNum(ha, t.consumption.noRespaldadaId, t.consumption.powerUnit === 'W' ? 1000 : 1)),
     batteryPower: round3(batteryPower),
     batteryStatus: batState || 'Desconocido',
     soc: round1(soc),
-    grid: round3(grid),
+    grid: gridDown ? null : round3(grid),
     solis: round3(inv0.kw),
     fox: round3(inv1.kw),
     inverters: invLive,
@@ -305,7 +321,7 @@ async function getDaySeriesUncached(ha, dateStr, db) {
 // (fila `daily` para días pasados; `liveTargets` para HOY, que aún no tiene
 // fila), para que la curva integre el mismo total que la fuente profunda.
 // Si se usó respaldo en algún bucket, la curva se marca `estimated`.
-function buildDaySeries(stats, dateStr, db, liveTargets) {
+export function buildDaySeries(stats, dateStr, db, liveTargets) {
   const t = getInstall()
   const invIds = t.inverters.flatMap((inv) => [inv.powerId, inv.backupPowerId].filter(Boolean))
   const ids = [...invIds, ...t.consumption.powerIds]
@@ -373,6 +389,15 @@ function buildDaySeries(stats, dateStr, db, liveTargets) {
 
     let grid = consumption - production + batteryPower
     if (Math.abs(grid) < 0.03) grid = 0
+    // Issue 135: si falta CUALQUIER entrada de la fórmula en el bucket
+    // (medidores de consumo o sensor de batería caídos), el grid derivado no
+    // es fiable → se suprime (null) en vez de computar con ceros, que de
+    // noche fabrica exportaciones imposibles. Si el hueco de consumo se
+    // rellena después (issue 125), el grid se recompute con el consumo
+    // estimado y el día queda marcado `estimated`.
+    const consMissing = consMeterIds.some((id) => b[id] === undefined || b[id] === null)
+    const batMissing = t.battery.enabled && t.battery.powerId && (b[t.battery.powerId] === undefined || b[t.battery.powerId] === null)
+    if (consMissing || batMissing) grid = null
 
     const hh = String(Math.floor(min / 60)).padStart(2, '0')
     const mm = String(min % 60).padStart(2, '0')
@@ -388,7 +413,7 @@ function buildDaySeries(stats, dateStr, db, liveTargets) {
       consumption: round3(consumption),
       batteryPower: round3(batteryPower),
       soc: round1(soc),
-      grid: round3(grid),
+      grid: grid === null ? null : round3(grid),
     })
   })
 
diff --git a/server/test/solar.test.js b/server/test/solar.test.js
index 48d3808..f6f8bc7 100644
--- a/server/test/solar.test.js
+++ b/server/test/solar.test.js
@@ -1,5 +1,5 @@
 import { describe, it, expect, afterEach } from 'vitest'
-import { computeLive, cachedCollector } from '../src/solar.js'
+import { computeLive, cachedCollector, buildDaySeries } from '../src/solar.js'
 import { _setForTests } from '../src/install.js'
 import { LEGACY_TOPOLOGY, GENERIC_TOPOLOGY } from '../src/install.js'
 
@@ -100,6 +100,92 @@ describe('computeLive — topología genérica (issue #37)', () => {
   })
 })
 
+describe('issue #135 — grid derivado con entradas caídas', () => {
+  // HA conectado con la topología LEGACY (3 medidores de consumo en W,
+  // batería con powerId/socId, grid por attrs del shim).
+  function haLegacy(overrides = {}) {
+    const map = {
+      'sensor.solis_potencia_actual': { state: '0' },
+      'sensor.almacen_pinza_power_b': { state: '0' },
+      'sensor.medidor_respaldo_power': { state: '500' },
+      'sensor.vivienda_medidor_power': { state: '200' },
+      'sensor.almacen_pinza_power_a': { state: '50' },
+      'sensor.solis_bateria_potencia': { state: '0' },
+      'sensor.solis_bateria_soc': { state: '50' },
+      'sensor.solis_bateria_estado': { state: 'Descargando' },
+      'sensor.solis_scraper': { state: 'ok', attributes: { currentGridPower: 0.7, gridDirection: 'import' } },
+      'sun.sun': { state: 'below_horizon', attributes: { elevation: -20 } },
+      ...overrides,
+    }
+    return { connected: true, getState: (id) => map[id] }
+  }
+
+  it('computeLive: un medidor de consumo caído → consumption null + alerta, grid intacto', () => {
+    _setForTests(LEGACY_TOPOLOGY)
+    const live = computeLive(haLegacy({ 'sensor.medidor_respaldo_power': { state: 'unavailable' } }))
+    expect(live.consumption).toBeNull()
+    expect(live.alerts.some((a) => a.id === 'consumo' && a.severity === 'warning')).toBe(true)
+    expect(live.grid).toBeCloseTo(0.7, 2) // la fuente de red sigue viva
+  })
+
+  it('computeLive: fuente de red (attrs) caída → grid null, sin fallback inventado', () => {
+    _setForTests(LEGACY_TOPOLOGY)
+    const live = computeLive(haLegacy({ 'sensor.solis_scraper': { state: 'unavailable', attributes: {} } }))
+    expect(live.grid).toBeNull()
+  })
+
+  // Buckets de noche que reproducen el caso real del 26-Sep: medidores de
+  // consumo caídos y batería descargando 3,3 kW. Antes: grid -3,3 kW
+  // (exportación imposible de noche). Ahora: null.
+  it('buildDaySeries: bucket sin medidores de consumo → grid null (no export imposible)', () => {
+    _setForTests(LEGACY_TOPOLOGY)
+    const stats = {
+      'sensor.medidor_respaldo_power': [
+        { start: '2026-09-26T19:55:00', mean: 500 },
+        { start: '2026-09-26T20:05:00', mean: 500 },
+      ],
+      'sensor.vivienda_medidor_power': [
+        { start: '2026-09-26T19:55:00', mean: 200 },
+        { start: '2026-09-26T20:05:00', mean: 200 },
+      ],
+      'sensor.almacen_pinza_power_a': [
+        { start: '2026-09-26T19:55:00', mean: 50 },
+        { start: '2026-09-26T20:05:00', mean: 50 },
+      ],
+      'sensor.solis_bateria_potencia': [
+        { start: '2026-09-26T19:55:00', mean: 3.3 },
+        { start: '2026-09-26T20:00:00', mean: 3.3 },
+        { start: '2026-09-26T20:05:00', mean: 3.3 },
+      ],
+      'sensor.solis_bateria_soc': [
+        { start: '2026-09-26T19:55:00', mean: 50 },
+        { start: '2026-09-26T20:00:00', mean: 49 },
+        { start: '2026-09-26T20:05:00', mean: 49 },
+      ],
+    }
+    const { points } = buildDaySeries(stats, '2026-09-26', null, {})
+    const p1955 = points.find((p) => p.label === '19:55')
+    const p2000 = points.find((p) => p.label === '20:00')
+    const p2005 = points.find((p) => p.label === '20:05')
+    expect(p1955.grid).toBeCloseTo(0.75, 2) // todo presente: 0,75 kW de import
+    expect(p2000.grid).toBeNull() // medidores caídos + batería descargando: antes -3,3 kW
+    expect(p2005.grid).toBeCloseTo(0.75, 2) // medidores recuperados
+  })
+
+  it('buildDaySeries: falta UN medidor de consumo (hueco parcial) → grid null', () => {
+    _setForTests(LEGACY_TOPOLOGY)
+    const stats = {
+      'sensor.medidor_respaldo_power': [{ start: '2026-09-26T21:00:00', mean: 500 }],
+      'sensor.almacen_pinza_power_a': [{ start: '2026-09-26T21:00:00', mean: 50 }],
+      'sensor.solis_bateria_potencia': [{ start: '2026-09-26T21:00:00', mean: 0 }],
+      'sensor.solis_bateria_soc': [{ start: '2026-09-26T21:00:00', mean: 50 }],
+    }
+    const { points } = buildDaySeries(stats, '2026-09-26', null, {})
+    expect(points).toHaveLength(1)
+    expect(points[0].grid).toBeNull() // consumo infrarreportado (0,55 en vez de 0,75): no fiable
+  })
+})
+
 describe('cachedCollector', () => {
   it('single-flight: N llamadas concurrentes = 1 ejecución', async () => {
     let calls = 0