EV Solar Charging & Bidirectional V2H Telemetry Engine
Model empirical AC-to-DC charging efficiency curves with auxiliary tare overhead, IEC 61851 6-Amp diverter boundaries, CT clamp main fuse dynamic balancing, and multi-day storm resilience using your electric vehicle.
If household non-EV load exceeds available capacity, charging dynamically throttles to prevent blowing the upstream utility service fuse.
24-Hour Energy Dispatch Stack & Priority Hierarchy
Resolving the Parasitic Battery Siphoning Conflict: Automated discharge lockout prevents draining home battery into EV.
Grid charges EV (32A) and Home ESS concurrently. Home ESS discharge is locked to eliminate parasitic siphoning.
Rooftop PV covers home baseload (Priority 1). Excess generation charges the stationary Home ESS (Priority 2).
With Home ESS full, smart diverter modulates pilot current between 6A and 32A into EV (Priority 3). Pauses below 1,380W.
Home runs from stored solar ESS, avoiding 38c daytime peak. EV charger remains idle until off-peak 8.15c window opens.
The 4-Way Annual Fuel Cost Shootout
Comparing annual driving expenses for 18,000 km in a Volkswagen ID.4 Pro
| Charging Strategy / Fuel Source | Effective Unit Rate | Conversion Efficiency | Annual Cost | Fuel Cost Reduction |
|---|---|---|---|---|
| Petrol ICE Car (7.2 L/100km) | €1.80 / Litre | ~25% ICE Thermal | €2,333 | Baseline |
| Daytime Grid Charging (Unmanaged) | 37.5c / kWh | 93.5% (Non-linear AC η) | €1,401 | -40% |
| Standard AC Wallbox + Night Boost (8.15c) | 8.15c / kWh | 93.5% (469W Tare Loss) | €128 | -95% |
| Sigenergy 25 kW DC Direct Fast Solar + Night Boost | 58% Solar + 8.15c | 97.0% Pure DC-to-DC Bus | €123 | -95% |
Vehicle-to-Home (V2H) Blackout Endurance by Load Scenario
Simulating how long a Volkswagen ID.4 Pro (61.6 kWh backup allocation) powers your home
Why 6A Solar Trickle Charging Wastes 25% Energy
Charging efficiency is governed by the ratio of fixed auxiliary overhead to delivered grid power. When an EV charges, the high-voltage contactors close and electronic control units (ECU), Battery Management System (BMS), and coolant pumps wake up, consuming a constant 280W to 350W.
- •At 6 Amps (1,380W): The 320W tare load represents 23.2% of total grid input, dropping net charging efficiency to 74.5%.
- •At 32 Amps (7,360W): That same 280W tare represents only 3.8%, yielding 92.5% charging efficiency.
- •Sigenergy 25 kW DC: Bypasses the vehicle onboard rectifier entirely, delivering 97% direct DC-to-DC charging.
Floating IT Earthing vs. Switched Neutral Manual Switches
Most Vehicle-to-Load (V2L) adapters provide an isolated Floating Neutral (IT Earthing). While safe for individual double-insulated appliances, connecting to a home panel presents critical grounding risks.
- •The RCD Trip Hazard: Connecting V2L into a standard transfer switch with shared neutral trips upstream residual current devices immediately.
- •Switched Neutral Required: A 3-pole or 4-pole switched-neutral transfer switch is legally required to isolate both live and neutral lines.
- •Statutory Compliance: Complies with ESB Networks NC6/NC7 and UK ENA G98 microgeneration islanding rules.
Frequently Asked Questions: EV Solar & Storage Telemetry
Why is EV charging efficiency lower at 6 Amps than 32 Amps?
When an EV charges, the high-voltage contactors close and electronic control units (ECUs), Battery Management System (BMS), and coolant pumps wake up, consuming a fixed auxiliary overhead of 280W to 350W. At 6A single-phase (1,380W), this 320W tare represents 23.2% of total power drawn, dropping net efficiency to ~74.5%. At 32A (7,360W), the fixed tare represents only 3.8% of power, yielding 92.5% charging efficiency.
Why does my EV charger drain my home battery during charging?
This issue is called Parasitic Battery Siphoning. Without CT clamp priority configuration, the home stationary battery detects the 7.4 kW EV wallbox as household load and discharges into the vehicle. Due to double conversion losses (89% ESS discharge × 88% EV charge = 78.3% round-trip efficiency), 21.7% of stored energy is wasted as heat, draining the home battery before morning. The solution is enabling Home ESS Discharge Lockout during off-peak night boost windows.
Can an electric car power a house during a storm with V2L?
Yes. Modern EVs with Vehicle-to-Load (V2L) such as the Hyundai Ioniq 5, Kia EV6, BYD Seal, and Ford F-150 Lightning deliver between 2.2 kW and 9.6 kW of islanded AC power. Reserving 20% for emergency driving, a 77 kWh battery provides 59.2 kWh of usable power—sufficient to run an essential emergency profile (fridge, sump pump, lights, Wi-Fi) for 6 to 8 continuous days.
What is the degradation cost of NMC vs LFP batteries for V2H arbitrage?
NMC battery chemistry incurs a cycle degradation wear cost of approximately €0.146 per kWh cycled (based on 1,500 cycle life at 80% DoD). LFP (Lithium Iron Phosphate) chemistry costs only €0.044 per kWh cycled (3,500 cycle life at 90% DoD). Consequently, LFP vehicles generate +€0.240/kWh net profit on 8.15c off-peak to 38c peak arbitrage, whereas NMC yields lower margins and should avoid low-margin V2G export.