Most businesses that invest in commercial solar and commercial EV charging do it twice. Solar first, as a standalone energy reduction project and EV charging later, when the fleet electrification pressure arrives. But this means two separate contractors, two separate site surveys, two separate commissioning processes, and sometimes two separate DNO applications. In short it costs more than it needs to, and it almost always produces a less effective result.
When both systems are designed together by a single contractor, the solar array is sized with the EV charging load in mind, the load management software is configured to route generation directly to the chargers, and the battery storage, where it’s part of the scope, bridges the gap between when the panels generate and when the vehicles charge.
Our commercial solar panel installations and EV charging services are routinely scoped together for exactly this reason. This article explains why the integrated approach produces better financial outcomes, better carbon reporting data, and a simpler operational setup for whoever manages the site.
Why These Two Systems Work Better Together
Solar generation and EV charging have naturally complementary energy profiles. Solar produces electricity during daylight hours. Commercial EV charging typically happens when vehicles are parked on site, which for most businesses means working hours and the early evening. That overlap isn’t perfect, but it is real, and exploiting it is the basis of the financial case.
Without EV charging, a commercial solar system typically achieves a self-consumption rate of 40 to 60%, depending on the site’s daytime energy use. The rest is exported to the grid under the Smart Export Guarantee (SEG) scheme. But SEG rates for commercial operators are significantly lower than the avoided cost of buying grid electricity, often in the range of 5 to 15 pence per kWh against grid purchase rates of 25 to 35 pence or more for many UK businesses in 2026. Every kilowatt-hour exported at SEG rates rather than consumed on-site represents a real financial opportunity missed.
Adding EV charging to an existing solar installation, or planning both together, increases the proportion of generation that is used on-site directly. Vehicles parked in the car park during working hours absorb solar generation that would otherwise be exported, the self-consumption rate rises, the financial return on the solar investment improves and the EV charging cost per session is reduced to the avoided cost of grid electricity, rather than the grid purchase price, because the energy was going to be generated regardless.
For a deeper explanation of how smart charging is configured to prioritise solar output and manage load across multiple chargers, our guide to smart EV charging and load management covers the technical setup. The point here is simpler: the two systems work better together because their energy profiles overlap, and that overlap translates directly into money.
The Financial Case: Self-Consumption, Avoided Cost, and Payback
The key metric for a commercial operator evaluating a combined solar and EV investment is self-consumption rate: what percentage of the solar generation stays on-site rather than being exported. It’s the number that most directly determines whether the investment returns what it should.
A commercial site running standard daytime operations without EV charging might achieve 50 to 60% self-consumption. If you add fleet vehicles charging during the day that figure typically rises to 70% or above. Then if you add battery storage it can reach 80% or higher on well-configured sites. Each percentage point gained is a kilowatt-hour shifted from a 5 to 15p SEG export payment to a 25 to 35p grid import avoided. Across a year, across a commercial system generating tens of thousands of kilowatt-hours, the difference in return is significant.
Commercial solar payback periods in the UK currently run at roughly 3 to 8 years depending on system size, grid electricity costs, and self-consumption rate. Sites with high daytime energy use and fleet vehicles to charge sit towards the faster end of that range. The Annual Investment Allowance lets businesses deduct 100% of qualifying capital expenditure on solar PV from their taxable profits in the year of purchase. At a 25% corporation tax rate, a £100,000 solar installation effectively costs £75,000 in cash terms after the allowance, which brings the payback period down meaningfully for tax-paying businesses.
The EV charging element adds to this. If vehicles are charging from solar-sourced electricity rather than the grid, the per-session energy cost is the avoided import cost rather than the grid purchase price. For a fleet doing significant annual mileage, the cumulative difference across the year is a genuine operating cost reduction, not a rounding error.
| Combining solar and EV charging produces better financial outcomes than buying them separately. Our commercial EV charger installation service is routinely scoped alongside commercial solar to ensure both systems are designed to work together. Get in touch to discuss your site. |
Where Battery Storage Changes the Calculation
Battery storage is the third component that extends the benefit of solar generation beyond the hours when the panels are producing. Without it, any generation that’s not immediately consumed is exported. With it, excess midday generation charges the battery, which then supplies the site in the late afternoon and evening when solar output has dropped.
For EV charging specifically, this is directly relevant where vehicles return to depot or a car park after normal working hours. A fleet that returns at 5pm or 6pm can charge from battery-stored solar generation rather than from the grid, extending the solar benefit into the evening window without requiring direct solar production. The proportion of overnight charging that can be solar-sourced depends on battery capacity relative to the solar array and the fleet’s charging demand, but a properly sized system can cover a meaningful share of it.
Battery sizing is informed by both the solar array output and the expected EV charging demand. This is one of the clearest examples of why designing both systems together produces a better result: if the battery is specified for a solar-only installation and EV charging is added later, it will almost certainly be undersized for the combined demand. Specifying it correctly from the start costs no more than getting it wrong and revisiting it.
MDG has done exactly this on its own site. Our PV system and battery storage case study covers how on-site generation, battery storage, and EV charging were integrated as a single system. The numbers from that installation inform how we approach the same question for commercial clients. For further context on the underlying case for combining solar and battery storage, our article on battery storage and energy independence covers the principles in more detail.
Carbon Reporting and ESG Outcomes
For businesses in scope for Streamlined Energy and Carbon Reporting (SECR), which applies to large companies meeting at least two of the following: turnover of £36 million or more, balance sheet of £18 million or more, or 250 or more employees, the combination of solar and EV charging produces directly reportable outcomes. SECR requires annual disclosure of UK energy use and associated greenhouse gas emissions, with Scope 2 emissions (from purchased electricity) being a mandatory component.
Solar generation displaces grid electricity, reducing Scope 2 emissions directly. EV charging supplied from on-site solar rather than the grid reduces the carbon intensity of the fleet’s energy consumption. When both systems report through the same management platform, the business has a single data source showing total kilowatt-hours generated, total kilowatt-hours self-consumed, total kilowatt-hours used for EV charging, and the carbon intensity of each source. That is the reporting structure needed for both SECR compliance and internal ESG disclosures.
The practical difficulty for many businesses is that solar and EV charging managed through separate systems produce separate data streams that require manual reconciliation. When both are designed and installed together, with a single integrated management platform, the reporting is straightforward. That is not a small operational advantage: the time spent reconciling energy data across systems is a real cost, and it grows with fleet and site size.
The Procurement Argument for a Single Contractor
Two contractors for two systems means two site surveys, two sets of design drawings, and two interactions with the DNO, which in many cases can be consolidated into a single application when both systems are being installed on the same site. It means two commissioning processes and two ongoing maintenance relationships. And it introduces technical risk at the boundary between the systems: if the EV charging load management software and the solar management platform are not configured to communicate, the smart routing of generation to chargers does not happen automatically.
A single contractor who designs and installs both systems eliminates that boundary. The solar array is sized with the EV load profile in mind, the battery storage, if included, is specified for the combined demand, the management software is configured as a single system from the start. On top of this the DNO application covers the full scope in a single submission and the commissioning process confirms that solar generation is routing correctly to the chargers before the project is signed off.
MDG scopes and delivers both services. The commercial solar panel installations and commercial EV charger installation services are regularly combined on the same site, and the MDG own-site case study is the evidence that the integration works in practice, not just in theory.
If your business is evaluating both investments, a single conversation is the right starting point. A site assessment covering solar potential, EV charging demand, battery sizing, and DNO position gives you a realistic combined project cost and a payback calculation that accounts for the interaction between the two systems rather than treating them as separate investments.
| To discuss a combined solar and EV charging project for your site, get a quote. One conversation, one site assessment, one integrated proposal covering both systems. |