Imagine charging your EV for free, using sunshine you've already paid to capture. With the right setup, UK homeowners can cover 30-60% of their annual EV charging with home-generated solar power.
This guide shows you how to integrate solar panels, home battery storage, and EV charging into one optimised system—maximising self-consumption and minimising grid dependence.
The opportunity: A well-designed solar + battery + EV system can save £800-£1,500 per year compared to grid-only charging.
Understanding the Solar + Battery + EV Ecosystem
How It Works Together
☀️ Solar Panels → Generate electricity during daylight
↓
🔋 Battery → Store excess for evening/overnight use
↓
🚗 EV Charger → Draw from battery/solar or grid as needed
The UK Reality Check
Before diving in, let's be realistic about UK solar:
UK Solar Generation (per 4kW system):
- Summer (June): ~20kWh/day on good days
- Winter (December): ~3-5kWh/day on good days
- Annual average: ~10-12kWh/day
- Cloudy days: 2-4kWh regardless of season
EV Charging Needs (typical):
- Daily average: 8-12kWh (for 25-35 miles)
- Weekly shop run + commute: 50-80kWh
- Solar can realistically cover: 30-60% of EV needs
💡 Key Insight: Solar alone won't fully charge your EV year-round in the UK. The goal is optimisation, not complete grid independence.
System Sizing: Getting the Balance Right
Solar Panel Sizing
For EV charging focus:
| Home Situation | Recommended Solar | Annual Generation | EV Coverage |
|---|---|---|---|
| Small home, 1 EV | 4kW (10-12 panels) | 3,400-3,800 kWh | 30-40% |
| Medium home, 1-2 EVs | 6kW (15-18 panels) | 5,100-5,700 kWh | 40-50% |
| Large home, 2 EVs | 8-10kW (20-25 panels) | 6,800-8,500 kWh | 50-60% |
Cost: £5,000-£8,000 for 4kW system; £8,000-£12,000 for 8kW system (2025 prices, installed)
Battery Storage Sizing
For EV integration:
| Battery Size | Best For | Cost (2025) |
|---|---|---|
| 5-6kWh | Basic solar storage, limited EV benefit | £3,000-£4,500 |
| 9-10kWh | Good balance, store afternoon sun for evening EV charge | £5,000-£7,000 |
| 13-15kWh | Maximise solar self-use, significant EV charging | £7,000-£10,000 |
| 20kWh+ | Near energy independence, multiple EVs | £12,000-£18,000 |
Popular UK batteries:
- Tesla Powerwall 2 (13.5kWh) - £8,500-£10,500 installed
- GivEnergy All-in-One (9.5-13.5kWh) - £5,500-£8,500 installed
- Sunsynk (5-16kWh modular) - £4,500-£12,000 installed
- Fox ESS (6-12kWh) - £4,000-£8,000 installed
EV Charger Selection
For solar integration, you need a "solar-aware" charger:
| Charger | Solar Integration | How It Works |
|---|---|---|
| Zappi | ✅ Excellent | Native solar tracking via CT clamp, ECO+ mode |
| Ohme | ✅ Good | Integrates with smart tariffs, solar-aware scheduling |
| Wallbox Pulsar Plus | ⚠️ Limited | Power Boost for load management, no native solar |
| Hypervolt | ✅ Good | Solar-aware with CT clamp option |
| Andersen A2 | ⚠️ Limited | Premium design, basic solar integration |
Recommendation: For dedicated solar integration, Zappi is the UK market leader.
The Zappi + Solar + Battery Setup
How Zappi Modes Work
ECO Mode:
- Uses solar generation only (won't draw from grid)
- Charging speed varies with sunlight
- Best for: Sunny days when car is home all day
ECO+ Mode:
- Uses solar plus 1.4kW from grid (minimum to start charging)
- More consistent charging even with variable cloud
- Best for: Typical UK conditions with variable weather
FAST Mode:
- Full power from any source (solar, battery, or grid)
- Ignores solar optimisation
- Best for: When you need charge quickly regardless of source
Zappi + Battery Integration
Direct integration (recommended):
- Zappi connects to your home's electricity via CT clamp
- CT clamp monitors grid import/export in real-time
- When solar is generating and exporting, Zappi increases charge rate
- When solar drops, Zappi reduces charge rate or pauses
- Battery can discharge to power Zappi (if configured)
System requirement: myenergi Hub for monitoring and remote control
Real-World Performance (UK Data)
Case Study: 6kW solar + 9.5kWh GivEnergy + Zappi (West Midlands)
| Month | Solar Generated | EV Charged from Solar | Grid Top-Up | Savings |
|---|---|---|---|---|
| June | 520 kWh | 180 kWh | 40 kWh | £52 |
| December | 85 kWh | 25 kWh | 195 kWh | £8 |
| Annual | 4,200 kWh | 980 kWh | 1,600 kWh | £320 |
Annual EV charging cost with this system: ~£185 (vs £650 grid-only)
Optimising Your System Configuration
Priority 1: Maximise Solar Self-Consumption
Without battery:
- Solar generates during day, but EV often not home
- Excess solar exported at ~4-5p/kWh (SEG rate)
- Evening charging costs 24-28p/kWh from grid
- Self-consumption: 30-40%
With battery:
- Excess daytime solar stored in battery
- Evening EV charging draws from battery first
- Grid only used when battery empty
- Self-consumption: 60-80%
Priority 2: Smart Tariff Integration
Best tariffs for solar + battery + EV:
Octopus Flux:
- Export rate: 20-24p/kWh (premium hours)
- Import rate: 28p/kWh (peak), 14p/kWh (cheap slots)
- Strategy: Export solar at premium, charge EV at cheap rate
Octopus Intelligent Go + Solar:
- 7p/kWh overnight charging
- Solar tops up during day
- Battery smooths the gap
Agile Octopus + Solar + Battery:
- Variable rates (sometimes negative!)
- Charge battery and EV when prices low/negative
- Use battery when prices high
- Requires active management or automation
Priority 3: Load Balancing and Priorities
Configure your system priorities:
- Home loads first - Lights, appliances, heating
- Battery charging second - Store excess for later
- EV charging third - Use remaining solar/battery
- Grid export last - Only if everything else full
Why this order?
- Home loads are immediate, can't be shifted
- Battery storage is most valuable (use tonight)
- EV can often wait or use grid overnight at cheap rates
- Export earns least (4-5p SEG, except Flux)
Cost-Benefit Analysis: Is It Worth It?
Installation Costs (2025)
| Component | Budget | Mid-Range | Premium |
|---|---|---|---|
| 6kW Solar | £5,500 | £7,000 | £9,000 |
| 10kWh Battery | £5,000 | £6,500 | £9,000 |
| Zappi EV Charger | £900 | £1,100 | £1,300 |
| Installation & Integration | £1,000 | £1,500 | £2,500 |
| Total | £12,400 | £16,100 | £21,800 |
Annual Savings
| Scenario | Annual Saving | Payback (Mid-Range) |
|---|---|---|
| Moderate use (8,000 miles/year) | £450-£600 | 27-36 years |
| Heavy use (15,000 miles/year) | £700-£950 | 17-23 years |
| Heavy use + export income | £900-£1,200 | 13-18 years |
| Heavy use + export + home energy savings | £1,200-£1,800 | 9-13 years |
Reality check: The EV charging savings alone don't justify the full system cost. The ROI only makes sense when you factor in:
- Home electricity savings (biggest factor)
- Export income (especially on Octopus Flux)
- Energy price hedging (protection from future rises)
- Environmental benefits (if you value these)
When Solar + Battery + EV Makes Sense
✅ Good candidates:
- Already planning solar installation
- High electricity usage household
- Working from home (car available during sunny hours)
- On export-friendly tariff like Octopus Flux
- Long-term home ownership planned
❌ May not make sense:
- Primarily driving at night (limited solar benefit)
- Moving house within 5-7 years
- Limited roof space or unsuitable orientation
- Tight budget (Intelligent Go tariff alone saves 70%+)
Installation Considerations
Electrical Requirements
Typical domestic installation needs:
- Consumer unit upgrade - May need to accommodate solar inverter, battery, and EV charger circuits
- G98/G99 application - DNO notification for solar (automatic for under 3.68kW)
- Balanced loading - Ensure your supply can handle all systems simultaneously
Typical supply capacity (single phase):
- Main fuse: 60-100A
- Solar inverter: 25-30A
- Battery: 15-25A
- EV charger: 32A
Important: Systems must be designed to avoid overloading. This is where integrated load balancing (like Zappi's CT clamp monitoring) is essential.
Finding the Right Installer
Look for:
- MCS certified (Microgeneration Certification Scheme) for solar
- Battery manufacturer accreditation (Tesla Certified, GivEnergy approved, etc.)
- NICEIC/NAPIT registration for electrical work
- Experience with integrated systems (solar + battery + EV)
Questions to ask:
- How will the systems communicate with each other?
- Can I monitor everything from one app?
- What happens during a power cut?
- How is the system future-proofed (V2G ready, capacity for expansion)?
Planning and Permissions
Solar panels:
- Usually permitted development (no planning permission needed)
- Exceptions: Listed buildings, conservation areas, flat roofs fronting a highway
Battery storage:
- Internal installation: No planning permission needed
- External installation: May need permission if large or prominent
EV charger:
- Usually permitted development
- Restrictions in conservation areas or near highways
Monitoring and Optimisation Apps
Recommended Monitoring Setup
For comprehensive visibility:
- myenergi app - Zappi control, solar diversion tracking
- GivEnergy portal (or your battery's app) - Battery state, flow monitoring
- Solar panel monitoring - Generation tracking (often via inverter app)
- Smart meter display - Real-time grid import/export
All-in-one options:
- Home Assistant - Free, open-source, integrates everything (requires technical setup)
- GivEnergy Cloud - Good integration if using GivEnergy battery
- Solar Assistant - Raspberry Pi-based monitoring for many inverter brands
Automations Worth Setting Up
- Charge EV from battery if battery >70% - Don't let battery fully drain
- Switch to grid charging at 10pm - When cheap rate starts (Intelligent Go)
- Export to grid during 4-7pm peak - If on Flux tariff (premium export rates)
- Notify when solar generation exceeds X - Reminder to plug in car
Frequently Asked Questions
Can I charge my EV purely from solar in the UK?
Rarely in practice. A typical UK solar system generates enough for a full EV charge on the best summer days, but winter generation is insufficient. The goal is supplementation, not replacement. Expect 30-60% of EV charging from solar annually.
Do I need a battery to charge my EV from solar?
No, but it helps significantly. Without a battery, you can only charge while the sun shines and your car is home. A battery stores daytime solar for evening/overnight charging, dramatically improving solar self-use.
What's the best EV charger for solar integration?
The Zappi by myenergi is the UK leader for solar integration. It has native solar tracking, multiple charging modes (ECO, ECO+, FAST), and integrates well with battery systems. The Ohme is a good alternative with smart tariff integration.
How much roof space do I need?
Roughly 15-20m² per kW of solar capacity. A typical 6kW system needs around 30-35m² of suitable roof space. South-facing is ideal, but east/west roofs work well too (split across both sides).
Can I add solar to an existing EV charger?
Yes, but integration varies. If you have a "dumb" charger, you won't get smart solar diversion. If you have an Ohme or Wallbox, some integration is possible via smart tariffs and scheduling. Zappi offers the most seamless retrofit solar integration.
Should I get battery storage if I only want to charge my EV from solar?
It depends on your driving patterns. If you're home during the day (work from home), you can charge directly from solar without a battery. If you're away during daylight hours, a battery is essential to capture solar for evening charging.
What happens to my solar system during a power cut?
Most grid-tied solar systems shut down during power cuts (anti-islanding safety requirement). However, some battery systems (like Tesla Powerwall) offer backup capability—your essential loads (possibly including EV charger) continue running from battery and solar. Check your specific system's capabilities.
