EV Charging and Solar Panel Integration: A Guide for Manchester Businesses
Combining EV charging with on-site solar generation is one of the most financially compelling energy investments a Manchester business can make in 2026. Electricity generated by your own solar panels costs approximately 4 to 6 pence per kWh over the system's lifetime — compared to 25 to 35 pence per kWh from the grid. When that free electricity goes directly into charging electric vehicles instead of being exported to the grid at 5 to 8 pence per kWh, the financial case becomes very strong.
This guide explains how solar PV and EV charging work together, what equipment and configuration you need, and what the realistic costs and returns look like for businesses across Greater Manchester.
How Solar and EV Charging Work Together
At its simplest, solar panels generate electricity during daylight hours and EV chargers consume electricity. The goal of integration is to maximise the proportion of solar electricity that goes directly into vehicles rather than being exported to the grid or drawn from the grid separately.
Solar Diversion Charging
Solar diversion is the most common integration approach. A solar diversion charger — such as the Zappi or a charger connected to an energy management system — monitors solar generation in real time and adjusts the charging rate to match the available surplus solar electricity.
On a sunny morning when your 50 kW solar array is generating 40 kW but your building is only using 25 kW, the remaining 15 kW is directed to EV charging. If cloud cover reduces generation, the charger automatically reduces its output or pauses. When the sun returns, charging resumes.
This approach ensures that solar electricity is used on site rather than exported at a fraction of its value. For businesses with vehicles parked during daylight hours — offices, depots, retail properties — this alignment is naturally strong.
Excess Solar Management
Without EV charging, most commercial solar installations export a significant proportion of their generation to the grid. Typical self-consumption rates for a commercial solar system without EV charging or battery storage are 30 to 50 per cent. Adding EV charging can increase self-consumption to 60 to 80 per cent, dramatically improving the financial return on the solar investment.
For a 50 kW commercial solar system generating approximately 42,000 kWh per year in Manchester:
- Without EV charging: Self-consumption of 20,000 kWh (£6,000 saved) plus export of 22,000 kWh (£1,320 at 6p per kWh). Total annual benefit: approximately £7,320.
- With EV charging: Self-consumption of 35,000 kWh (£10,500 saved) plus export of 7,000 kWh (£420). Total annual benefit: approximately £10,920.
System Design and Equipment
Solar Panel Array Sizing
The optimal solar array size depends on your roof space, electricity demand profile and how many EVs you expect to charge. For most commercial properties in Manchester, we recommend sizing the array to match your daytime baseload plus a margin for EV charging.
Typical commercial solar array sizes:
- Small office (10 to 20 staff): 15 to 25 kW (40 to 65 panels)
- Medium office or retail unit: 30 to 50 kW (80 to 130 panels)
- Large commercial or industrial: 50 to 100 kW (130 to 260 panels)
- Warehouse or distribution centre: 100 to 250 kW (260 to 650 panels)
EV Charger Selection for Solar Integration
Not all EV chargers support solar integration equally. Key features to look for include:
CT clamp compatibility — The charger must accept input from a current transformer monitoring solar generation and building consumption. This allows the charger to calculate surplus solar electricity in real time.
Variable charge rate — Solar generation fluctuates with cloud cover. The charger must be able to modulate its output smoothly between zero and maximum, not just switch on and off. The minimum useful charging rate is typically 1.4 kW (6 A single-phase), below which most vehicles will not charge.
OCPP compatibility — The Open Charge Point Protocol allows integration with third-party energy management systems. For larger installations with multiple chargers, OCPP provides centralised control of solar diversion across all units.
Scheduling override — Even with solar diversion active, you need the ability to force full-rate charging from the grid when a vehicle needs charging urgently regardless of solar availability.
Battery Storage: When It Makes Sense
Adding battery storage to a solar and EV charging system allows you to store excess solar generation during the day and use it for EV charging in the evening or overnight. This is particularly valuable for businesses where vehicles arrive or need charging outside peak solar hours.
When battery storage is worth the investment:
- Vehicles are typically charged overnight or in the evening after solar generation has ended
- Your electricity tariff has very high peak-rate charges that battery storage can offset
- You want to maximise solar self-consumption above 80 per cent
- You are interested in grid services revenue from battery discharge during peak demand
- Vehicles are parked and available for charging during daylight hours (direct solar charging is simpler and cheaper)
- Your budget is limited — battery storage adds £400 to £600 per kWh of storage capacity
- Your priority is minimising payback period rather than maximising self-sufficiency
Costs and Financial Returns
Combined Solar and EV Charging Installation Costs
Solar PV system:
- 25 kW system: £18,000 to £25,000
- 50 kW system: £32,000 to £45,000
- 100 kW system: £55,000 to £80,000
EV chargers with solar integration:
- 4 x 7.4 kW smart chargers with solar diversion: £5,000 to £10,000
- 8 x 22 kW chargers with load management and solar integration: £15,000 to £30,000
- 10 kWh commercial battery: £5,000 to £7,000
- 30 kWh commercial battery: £14,000 to £20,000
- 100 kWh commercial battery: £40,000 to £60,000
Payback Period
For a typical medium-sized Manchester business installing a 50 kW solar system with four EV chargers:
- Total installation cost: approximately £45,000 to £55,000
- Annual electricity savings (solar self-consumption): £10,000 to £12,000
- Annual EV charging cost avoidance: £3,000 to £5,000
- Simple payback period: 3.5 to 4.5 years
Tax Benefits
Commercial solar installations qualify for 100 per cent first-year capital allowances under the full expensing regime. For a corporation tax-paying business, this means 25 per cent of the installation cost is effectively refunded through reduced tax liability in the year of installation.
EV chargers installed for employee use also qualify for capital allowances and may attract enhanced capital allowances for energy-saving equipment.
Installation Considerations for Manchester Properties
Roof Assessment
A structural survey is required before installing solar panels on any commercial roof. Key factors include roof age and condition, structural load capacity (solar panels add approximately 12 to 15 kg per square metre), roof orientation and pitch (south-facing is optimal but east-west configurations work well), and shading from adjacent buildings, trees or equipment.
Many commercial roofs in Manchester are flat, which actually simplifies solar installation. Panels are mounted on ballasted frames at an optimal tilt angle of 30 to 35 degrees without any roof penetration.
Electrical Integration
The solar system and EV chargers must be integrated with your existing electrical installation. This involves connecting the solar inverter to your main distribution board, installing current transformers for generation and consumption monitoring, configuring the energy management system to prioritise solar self-consumption, and ensuring all protection devices are correctly rated and coordinated.
A qualified electrician experienced in both solar PV and EV charging should design and install the complete system. Poor integration is the most common reason that solar and EV systems fail to deliver their expected savings — if the monitoring is inaccurate or the control logic is wrong, solar electricity gets exported instead of used for charging.
DNO Notification and G99 Compliance
Solar installations above 3.68 kW require notification to Electricity North West under the G99 engineering recommendation. Systems above 50 kW require formal application and approval before connection, which can take four to eight weeks. Your installer should handle this process as part of the project.
Monitoring and Optimisation
Once installed, ongoing monitoring ensures your system performs as expected. A good energy management dashboard shows real-time solar generation, building consumption, EV charging consumption, grid import and export, and the proportion of EV charging powered by solar versus grid electricity.
Review these figures monthly for the first year to identify any underperformance. Common issues include incorrect CT clamp positioning giving inaccurate readings, charger firmware not responding correctly to solar surplus signals, and shading from seasonal tree growth reducing afternoon generation.
Getting Started
The first step is a combined site survey assessing both your roof suitability for solar and your electrical infrastructure for EV charging. At Manchester Compliance, we design and install integrated solar and EV charging systems across Greater Manchester, ensuring both systems work together to deliver maximum financial return.
Contact us to arrange a free site assessment. Call 0161-XXX-XXXX or email hello@manchestercompliance.co.uk.