Engineering report · reviewed against NEC 2026 & BS 7671:2018+A2
Engineering Breakdown: Running a BYD Atto 3 / Dolphin (7kW AC Charging) on the Bluetti AC300 + B300K
When pairing the Bluetti AC300 + B300K (2,764 Wh LiFePO4 capacity, 3,000 W continuous, 6,000 W surge) with a BYD Atto 3 / Dolphin (7kW AC Charging) (7,200 W running, 7,200 W starting surge), the system operates at 240% of continuous inverter capacity on a 230 V UK/EU/AU circuit. Our UK/EU/AU verdict is Continuous Overload, so the runtime figures below are theoretical battery-energy values only. Wiring the connection over a 7.5 m run calls for a 32 A MCB and 4.0 mm² copper, terminated at a Type 2 EVSE · IEC 60309 32A Commando connection.
1. Compatibility Verdict & Inverter Load Utilization
In UK/EU/AU 230 V mode the BYD Atto 3 / Dolphin (7kW AC Charging) loads the Bluetti AC300 + B300K's inverter to 240% of its 3,000 W continuous rating and 120% of its 6,000 W surge rating. Because continuous demand exceeds the inverter by 4,200 W, the unit will shut down within seconds of starting the load. The Sungrow SH10RS Hybrid Inverter + Battery is the smallest compatible upgrade.
| Check | Load requires | Bluetti AC300 + B300K provides | UK/EU/AU |
|---|---|---|---|
| Continuous output | 7,200 W | 3,000 W | Fail |
| Start-up surge | 7,200 W | 6,000 W | Fail |
| Voltage | 230 V | 230 V | Pass |
| Connection | Type 2 EVSE · IEC 60309 32A Commando | Schuko CEE 7/3 / BS 1363 13A outlets |
This is a 230 V market charging profile: the 7,200 W figure is the single-phase Type 2 (IEC 62196) rate of 31 A × 230 V. EV supply equipment is a constant-current load with no start-up surge, so the inverter only has to sustain the set current. To stay under the 80% sustained-load guideline, cap the charge current at 10 A in the vehicle or charger app, which holds the Bluetti AC300 + B300K near 2,300 W. In the UK, a charge point must meet BS 7671 Section 722 and the Electric Vehicles (Smart Charge Points) Regulations; in Australia and New Zealand, AS/NZS 3000 Section 7 and local network limits apply. A full battery puts about 2.1 kWh into the pack after losses — roughly 12 km (7 miles) of range.
The Bluetti AC300 + B300K is a modular system: the inverter head and battery packs stack together, so capacity can grow later without replacing the inverter. Its NEMA TT-30R / 5-20R outlet makes generator-style transfer-switch wiring straightforward.
Compatible alternative: the Sungrow SH10RS Hybrid Inverter + Battery with the BYD Atto 3 / Dolphin (7kW AC Charging) report shows the full sizing for a unit that passes all three checks.
2. Real-World Runtime by Duty Cycle
Nameplate capacity is not usable capacity. DC-to-AC conversion, battery management overhead and cell protection reduce the 2,764 Wh rating to about 2,349 Wh of deliverable AC energy (85% system efficiency). EV charging runs at a fixed current, so the 100% row is the realistic figure; lower rows apply only if you schedule charging in intervals.
| Duty cycle | Average draw | Runtime (no solar) | Energy per 24 h |
|---|---|---|---|
| 25% | 1,800 W | 1.3 hrs | 43.2 kWh |
| 50% | 3,600 W | 39 min | 86.4 kWh |
| 65% | 4,680 W | 30 min | 112.3 kWh |
| 100% | 7,200 W | 20 min | 172.8 kWh |
Even at a 50% duty cycle the battery lasts 39 min, so plan on solar, grid or generator recharging for anything longer than an evening outage. Because the inverter cannot actually run this load in UK/EU/AU mode, treat these numbers as an energy-budget reference for a compatible inverter of the same capacity.
3. BS 7671 / IEC 60364 Breaker & Cable Sizing
IEC-based codes size protection by design current rather than a blanket 125% multiplier: Ib ≤ In ≤ Iz. At 230 V the load draws 31.3 A, so a 32 A Type B/C MCB with RCD protection applies. In the UK, BS 7671 Section 722 additionally requires a dedicated circuit and Type A or Type B RCD for EV charge points.
| One-way distance | MCB | Min. cable | Voltage drop |
|---|---|---|---|
| 7.5 m (25 ft) | 32 A | 4.0 mm² | 0.94% |
| 15 m (49 ft) | 32 A | 4.0 mm² | 1.88% |
| 22.5 m (74 ft) | 32 A | 4.0 mm² | 2.82% |
| 30 m (98 ft) | 32 A | 6.0 mm² | 2.52% |
Moving the Bluetti AC300 + B300K from 7.5 m to 30 m away forces the conductor up from 4.0 mm² to 6.0 mm² — park the unit as close to the load as ventilation and weather protection allow.
4. Solar Array Recharge Time Breakdown
The Bluetti AC300 + B300K accepts up to 2,400 W of photovoltaic input. Real arrays rarely deliver nameplate output, so we apply an 80% harvest factor for MPPT conversion, cell temperature and soiling, and convert hours to days using 4.5 peak-sun-hours — a conservative annual average for the US, southern Europe and Australia (UK winters can fall below 1.5).
| PV array | Real harvest | 0–100% recharge | Sun-days @ 4.5 PSH | Net with load @ 50% |
|---|---|---|---|---|
| 400 W | 320 W | 8.6 hrs | 1.9 | −3,280 W |
| 800 W | 640 W | 4.3 hrs | 1.0 | −2,960 W |
| 1,600 W | 1,280 W | 2.2 hrs | 0.5 | −2,320 W |
| 2,400 W | 1,920 W | 1.4 hrs | 0.3 | −1,680 W |
A typical 800 W portable array refills the battery in about 4.3 hrs of strong sun, while maxing out the 2,400 W input cuts that to 1.4 hrs. To fully offset the BYD Atto 3 / Dolphin (7kW AC Charging) at a 50% duty cycle (3,600 W average) during daylight you need roughly 4,500 W of panels, which exceeds this unit's 2,400 W input limit — solar can slow the drain but not eliminate it.
5. Frequently Asked Questions
Can the Bluetti AC300 + B300K run a BYD Atto 3 / Dolphin (7kW AC Charging)?
Not reliably in the UK, Europe and Australia — our verdict is "Continuous Overload". The 7,200 W running load exceeds the 3,000 W inverter. The Sungrow SH10RS Hybrid Inverter + Battery is a compatible alternative.
How many miles of range can the Bluetti AC300 + B300K add to a BYD Atto 3 / Dolphin?
A full 2,764 Wh charge delivers about 2.1 kWh to the vehicle battery after inverter (85%) and on-board charger (90%) losses — roughly 7 miles at 3.5 mi/kWh. Charging at this profile is not possible on this unit without reducing current or changing voltage.
What breaker and wire size do I need to connect a BYD Atto 3 / Dolphin (7kW AC Charging) to the Bluetti AC300 + B300K?
At 230 V the load draws 31.3 A. Under BS 7671 / IEC 60364 the protective device must be at least the design current (Ib ≤ In ≤ Iz), so use a 32 A MCB with RCD protection on 4.0 mm² copper cable for runs up to 7.5 m (0.9% voltage drop). Connection: Type 2 EVSE · IEC 60309 32A Commando.
How long does it take to recharge the Bluetti AC300 + B300K with solar panels?
With an 800 W array and an 80% real-world harvest factor, a full recharge takes about 4.3 hrs of peak sun (1.0 days at 4.5 peak-sun-hours). At its maximum 2,400 W solar input it drops to 1.4 hrs.
Methodology & safety note
Specifications come from manufacturer datasheets in our open dataset; ampacity and resistance values follow NEC Table 310.16 and Chapter 9 Table 8, and BS 7671 Appendix 4. Calculations assume copper conductors, 30 °C ambient and no bundling derating. Inverter-to-panel connections require a listed transfer switch or interlock to prevent back-feeding the grid. These results are an engineering estimate, not a substitute for a licensed electrician and local permit. See our methodology and safety disclaimer.