Solar, Battery and EV Charging: How the Technologies Work Together

Why solar, battery and EV charging belong together

Most businesses buy these three technologies separately, from three different suppliers, at three different times. That is usually a mistake. Solar battery and EV charging are not three isolated products: they are one integrated system, and the whole is worth considerably more than the sum of the parts. Solar generates cheap power through the working day, a battery stores whatever you do not use immediately, and smart EV charging draws on that stored solar while managing your peak demand. Design them together and a UK business can charge a fleet or staff cars at a few pence per kWh instead of buying grid electricity at 25 to 45p, or forecourt fuel at far more, while often avoiding an expensive supply upgrade.

The reason the combination works is that each technology fixes a limitation of the others. Solar on its own only helps while the sun is up and typically covers 55 to 85 per cent of daytime load. Batteries on their own just shift grid power around. EV chargers on their own add a large new load that can push you over your available supply capacity. Put together and controlled intelligently, they cover for each other across the day.

How the integrated system actually works

Picture a typical commercial site across 24 hours. In the morning the solar array starts generating. That power first supplies the building, then any surplus charges the battery and tops up any vehicles plugged in. Through the middle of the day, when generation peaks and the office or unit cannot use it all, the battery fills and cars charge on essentially free power. As the sun drops and the working day ends, the battery discharges to cover the evening load, and overnight the EV chargers draw on cheap off-peak grid tariffs or remaining stored solar to have the fleet ready for the morning.

The intelligence sits in the load management layer. Smart charging, which is mandatory under The Electric Vehicles (Smart Charge Points) Regulations 2021, lets the system stagger and throttle charging so a bank of chargers never all draw full power at once. Load balancing shares your available supply dynamically between the building, the chargers and the battery. This is the feature that most often lets a site add EV charging without paying for a Distribution Network Operator supply upgrade, which can run to tens of thousands of pounds and many months of delay.

What each part contributes

Technology	Its job in the system	Typical business benefit
Solar PV	Generates cheap daytime power on your roof, land or car park	55-85% used on site; underpins a 5-8 year payback
Battery storage	Stores surplus solar for evening, weekend and overnight use	Lifts self-consumption from 55-75% up to 80-95%
EV charging	Charges fleet and staff vehicles on that stored solar	Fuel switched from forecourt prices to a few pence/kWh
Load management	Balances demand so nothing overloads the supply	Often avoids a costly DNO grid upgrade

A battery typically lifts the share of your own solar that you actually use from 55 to 75 per cent up to 80 to 95 per cent, and it shaves the expensive peak-demand and DUoS charges that make up a growing slice of a commercial bill. EV charging then turns that stored, self-generated power into transport at a marginal cost that grid charging and diesel cannot approach.

A representative example

Consider a modelled logistics operator running a distribution unit near Birmingham, with around £110,000 a year in electricity and a growing electric van fleet. An integrated design might combine roughly 220 kW of rooftop solar, a 215 kWh battery and twelve 22 kW chargers. The battery covers the early-shift ramp before the sun is fully up, the solar charges vans through the day, and load balancing keeps the whole depot inside its existing supply. In a build like this, self-consumption can reach the low 80s per cent, the fleet charges on self-generated power, and the whole package can be funded through an on-site Power Purchase Agreement at zero capex with the chargers part-funded by the Workplace Charging Scheme. This is a representative model, not a specific named client, but the economics are typical of a well-sequenced integrated system.

The order to build in

You do not have to install everything at once, and you should not. The sequence that maximises return is to measure and cut waste first, then generate, then store and electrify. In practice that means starting with an energy audit and quick efficiency wins, then sizing solar to your reduced consumption, then adding the battery once you have a year of real data on your load shape, and layering in EV charging as the fleet electrifies.

Crucially, a well-designed first phase is future-proofed. Most commercial solar systems are specified battery-ready and EV-ready from day one, so the inverter, switchgear and cabling can accept storage and chargers later without rework. This lets a business phase capital across budget years while protecting the eventual integrated design. If you are weighing up where to begin, our guide to what renewable energy costs a business sets out the numbers for each measure side by side.

Funding and the tax position

The three technologies share a strong funding picture. Solar PV, battery storage and EV chargepoints all qualify as plant and machinery for 100% Annual Investment Allowance and Full Expensing, so a profitable company deducts the full cost from taxable profit and recovers roughly a quarter of it through corporation tax, with VAT separately reclaimable. On top of that, the Workplace Charging Scheme gives £350 per socket for up to 40 sockets, and the EV infrastructure grant adds up to £15,000 toward wiring and groundworks for smaller businesses. Exported surplus solar earns income under the Smart Export Guarantee, typically 4 to 15p per kWh.

If capex is the barrier, an on-site Power Purchase Agreement lets a funder own the solar and battery while you simply buy the power below grid price at zero upfront cost. Our grants and funding guide covers the current schemes and eligibility in full. Note that the domestic Boiler Upgrade Scheme does not apply to commercial buildings, so ignore any advice that leans on it for a business site.

What to watch out for

An honest word on where integrated systems go wrong. The most common failure is sizing each element in isolation: a solar array sized to the roof rather than the load, a battery too big for the surplus it will ever see, or a bank of chargers specified without checking the incoming supply. All three are avoided by designing from half-hourly meter data rather than nameplate figures. The second pitfall is treating smart charging and load management as optional extras; without them, adding chargers to a site already running solar and battery can trip the supply or force an unnecessary grid upgrade.

The compliance side is manageable but real. Grid-connected solar and storage need a G99 application to your DNO, with G100 export or import limiting often used to secure a connection faster and avoid reinforcement. Chargepoints and the installer must be OZEV-approved for grant eligibility. None of this is difficult with a specialist handling it, but it is why the three technologies are best planned as one project.

The bottom line for a UK business

Solar, battery and EV charging deliver their best return as a single, intelligently controlled system rather than three separate purchases. Solar supplies cheap daytime power, the battery captures the surplus and shifts it to when you need it, and smart EV charging turns that stored energy into low-cost, low-carbon transport while load management protects your supply. Sized from your real consumption data, phased sensibly across budget years, and funded through capital allowances, grants or a zero-capex PPA, the combination cuts both your Scope 1 and Scope 2 emissions and keeps the whole programme cash-positive.

If you want an independent view of how these technologies would fit your building, load profile and fleet, request a free assessment and costed quote. We size and model the integrated system from your meter data, show you the numbers behind every claim, and tell you honestly which measures to do first and which to leave until later.