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Battery Investment Analysis LIVE DATA

6.65kW solar · 363 days actual data · Apr 2025–Mar 2026
$
📈 Grid Draw Summary — Actual Data (excl. holiday Jan 1–18)
☀️ Summer daytime grid draw
6.1 kWh
6am–9pm · Oct–Mar · 164 days
🌙 Summer nighttime grid draw
9.8 kWh
incl Tesla ~6.9kWh · 2.9kWh house
🌤️ Winter daytime grid draw
8.3 kWh
6am–9pm · Apr–Sep · 181 days
❄️ Winter nighttime grid draw
9.7 kWh
incl Tesla ~6.8kWh · 2.9kWh house
☀️ Summer solar avg
25.4 kWh
daily generation · Oct–Mar
🌤️ Winter solar avg
11.3 kWh
daily generation · Apr–Sep
📊 Grid draw figures are from Powerpal (smart meter) only — these show what you actually pulled from the grid each period. They do not include solar energy consumed directly by the house. Total actual consumption = grid draw + solar self-consumed (which averages an additional 8–22 kWh/day depending on season).
🔴 Why is the grid draw so high on some days? The red line spikes (30–50 kWh) are Tesla charging overnight. On peak Tesla nights the charger draws ~4–4.7 kWh/hour for 5–6 hours (midnight–6am) = up to 28 kWh Tesla alone in one night. House baseline (fridge, freezer, router) is only ~2.9 kWh/night. With the battery + Tesla shifted to daytime free window, these overnight spikes disappear entirely.
⚡ Daily Energy Flow

Solar generation, self-consumption & draw from grid

Solar generated Solar self-consumed Solar exported (feed-in) Draw from grid (spikes = Tesla overnight)
🔋 Battery Level Simulation

Estimated daily battery state of charge (%)

Battery level % Grid shortfall (kWh, right axis) Shading = winter months (Jun–Aug)

Daily battery charging sources (kWh)

Solar surplus → battery (actual feedin data) Free window 11am–2pm grid charge ($0, strategy) Battery discharge need (line) ■ Yellow = holiday Jan 1–18
💰 Daily Savings

Daily electricity saving vs current (no battery)

Daily saving ($) ZeroHero day ($1 earned)
📊 Payback Analysis

Year-on-year payback estimate

⚡ Gas → reverse-cycle aircon saving (~$550/yr) NOT included above. Add this for true payback — reduces payback by ~0.8–1.2 years depending on scenario. See monthly detail tab.
📋 Data sources: GoodWe solar app (daily generation, Apr 2025–Mar 2026) · GloBird B1 meter (solar feed-in/export, 30-min intervals) · Powerpal smart meter (grid draw, hourly) · 363 overlapping days used for simulation.
⚠️ Assumptions: 5kW FoxESS KA5 battery inverter (max 5kW charge rate) · Free window 11am–2pm = 15kWh/day from grid at $0 · Tesla = 70% of evening grid draw · Peak rate $0.308/kWh · Off-peak $0.168/kWh · ZeroHero $1/day when no grid 6–9pm.