🌿 Rose Cottage — August 2026

Monthly Solar & Battery Generation Report · 1–31 August 2026

1,784kWh combined generation

☀️ Enphase: 22× 510W Aiko · IQ8HC micros · 11.2 kWp ☀️ Sonnen-connected original array 🔋 Sonnen hybrid battery

1,784 kWh
Combined generation
944.5 kWh
Exported (Sonnen)*
614.6 kWh
Imported (Enphase)*
+329.9 kWh
Net exporter

* Octopus smart-meter data (normal source of truth) stopped updating on 26 Aug ~13:00 BST, so full-month export uses the Sonnen grid meter and import uses the Enphase CT clamp. Octopus partial figures to 26 Aug: 850.8 kWh exported / 447.5 kWh imported.

Month at a glance

1,208.4 kWh

Enphase generation

Enlighten, 39.0 kWh/day avg

575.9 kWh

Sonnen solar

47.7% of Enphase — in expected 45–50% band

1,784.3 kWh

Combined total

57.5 kWh/day average

£181.40

Estimated savings

Enphase currency equivalent of production

125.9 kWh

Battery charged

Homey · Sonnen meter

162.9 kWh

Battery discharged

Homey · Sonnen meter

614.6 kWh

Grid imported

Enphase CT (Octopus partial: 447.5)

944.5 kWh

Grid exported

Sonnen meter (Octopus partial: 850.8)

System specifications

Enphase array — 11.22 kWp

22× 510W Aiko panels with IQ8HC microinverters (Enlighten Site ID 5848331).
North main roof: 9 panels (Az 25°, Tilt 34°) · South main roof: 9 panels (Az 205°, Tilt 34°) · Garage: 4 panels (Az 180°, Tilt 30°).

Sonnen system — original array + storage

Original solar array connected through the Sonnen hybrid inverter, typically producing 45–50% of Enphase output (47.7% this month), with integrated Sonnen battery storage handling charge/discharge and grid metering.

Daily combined generation

Combined generation per day (Enphase + Sonnen, kWh)

🏆 Peak day: Sat 2 Aug — 79.1 kWh (Enphase 55.6 + Sonnen 23.5). Quietest: 29 Aug — 25.9 kWh. Weekly totals: 466.6 / 497.2 / 337.7 / 375.2 / 107.3 (3 days) kWh.

Battery performance

Charged into battery

125.9 kWh

Discharged to house

162.9 kWh

Busiest discharge day: 14 Aug — 8.8 kWh delivered from storage. Average discharge ≈ 5.3 kWh/day, covering evening and overnight loads.

The meters recorded more energy leaving the battery than entering it this month, which is not physically possible over a full cycle — the Homey 6-hourly averaging of the Sonnen cumulative counters (which showed occasional small dips) is the likely cause. Treat the split as indicative; a round-trip efficiency figure isn't quoted for August for this reason.

Grid interaction

Exported (Sonnen, full month)

944.5 kWh

Exported (Octopus, to 26 Aug)

850.8 kWh

Imported (Enphase, full month)

614.6 kWh

Imported (Octopus, to 26 Aug)

447.5 kWh

Rose Cottage was a net exporter of ~330 kWh in August (Enphase's own net-export figure: 324.0 kWh). The house consumed 885.3 kWh, of which solar covered roughly 70% directly or via the battery. Grid consumption routed through the Sonnen meter was 300.8 kWh (reference).

Analysis

A month of two halves. The first fortnight was excellent — 1,026 kWh combined (68 kWh/day) with a run of 70+ kWh days peaking at 79.1 kWh on 2 August. From mid-month, conditions turned noticeably duller: the second half produced 758 kWh, with the weakest spells around 16–18, 27 and 29 August (25.9 kWh on the 29th), consistent with unsettled late-summer weather and shortening days.

Versus July. Enphase generation fell 24.9% (1,609.6 → 1,208.4 kWh) — the usual seasonal step-down from peak summer. Export dropped 28% (1,311.5 → 938.0 kWh on the Enphase meter) while imports rose ~15% (527.5 → 605.6 kWh) and home consumption crept up 6% (825.5 → 876.8 kWh), so the net-export margin narrowed but remained comfortably positive.

Array balance. The Sonnen-connected array produced 47.7% of Enphase output, right in the middle of its expected 45–50% band — both arrays are performing to spec. Solar offset for the month was 137% of household consumption (Enphase), with a CO₂ reduction equivalent of 876.5 kg.

Watch item. The Octopus meter feed in Homey went stale at 26 August ~13:00 BST (import frozen at 85,973.2 kWh, export at 9,496.9 kWh). Worth checking the Octopus integration in Homey so September's report can use metered figures for the full month.

Data sources

Metric	Source	Notes
Grid import / export	Octopus smart meter (Homey)	Source of truth, but stale after 26 Aug — full-month figures fall back to Enphase CT (import) and Sonnen grid meter (export)
Enphase generation, consumption, savings	Enphase Enlighten (Site 5848331)	Month view + daily energy API; savings = currency equivalent of production
Sonnen solar generation	Homey Insights (Sonnen production)	6-hourly average power integrated over the month; final evening slot of 31 Aug estimated (~0.1 kWh)
Battery charge / discharge	Homey Insights (Sonnen totals)	Monthly delta of cumulative counters, midnight-to-midnight