Solar PV, Battery Storage and EV Charger Installation: How We Design the Complete System

Author: Steve Fairless
Originally Published: 4th June 2025 · Updated: 2nd September 2026

When solar PV, battery storage and EV charging are installed together, we design them as one electrical energy system rather than three unrelated products. The PV creates energy, the battery shifts energy through time, the EV charger adds a large flexible load, and all three interact with the property's supply, metering, tariffs and DNO connection.

At Sustainable Energy Engineering, our process starts before the survey. We gather the customer's electricity use, property information and future plans, develop an initial proposal, then confirm the roof, electrical installation and connection requirements before equipment is ordered. The goal is a system that works as a whole on day one and still makes sense when energy use changes.

That integrated approach is especially important for customers who expect to electrify heating, add a second EV or expand battery capacity later. A solar inverter, battery and charger can all be individually good products and still make a poor overall system if their power limits, controls or connection assumptions do not align.

Updated: 2nd September 2026.

Step 1: Your Enquiry Goes Into Our In-House Project Workflow

Most customers begin by reading our website, comparing solar, battery and EV options and then submitting an enquiry. We track enquiries through our in-house process so the information gathered at the beginning follows the project rather than being lost between sales, survey and installation.

Depending on the information available, we can discuss the project first or prepare an initial remote proposal. We want enough detail for the first design to be useful: annual electricity use, recent bills, roof photographs or address, current tariff, EV details and whether battery backup or future expansion matters.

Step 2: Solar Generation Is Only One Part of the Energy Model

For solar PV, we estimate the annual generation from the proposed array using the roof geometry, location and shading. MCS MIS 3002 Issue 6.0 provides the structured performance-estimation and handover requirements used for MCS solar PV projects, including the effect of roof geometry, location and shading.

We then compare that generation with consumption. A customer who drives home at 6pm and plugs in an EV may have a very different solar self-consumption profile from someone whose car sits on the driveway during the day. Battery storage can bridge part of that timing gap, but it has finite energy capacity and power.

Step 3: Survey the Roof and the Electrical System Together

A roof survey confirms what can actually be installed. We check dimensions, covering, condition, structure, mounting zones, shading, access and cable routes. At the same visit, or as part of the same design process, we establish the electrical route from PV and battery equipment to the distribution board and the route to the EV charger.

This matters because cable routes compete for space, equipment needs service clearances and the charger may be on a garage or driveway some distance from the main supply. Treating each technology separately can produce duplicated work or controls that do not communicate properly.

Step 4: Size Solar Around Energy Use and Roof Opportunity

We do not automatically fill every roof or size the array only to current annual demand. We look at future electricity use, the value of export, inverter capability and whether additional generation can be used by an EV, battery or heat pump.

Sometimes a larger array makes sense because an EV will increase demand. Sometimes the roof can hold more modules but the marginal generation is heavily shaded or creates a poor string configuration. The engineering decision is to install the useful array, not chase the largest headline kWp.

Step 5: Size the Battery in Both kWh and kW

Battery capacity in kWh tells us how much energy can be stored. Charge and discharge power in kW tells us how quickly that energy can move. Both matter in an integrated system.

A 10 kWh battery may have enough energy for an evening, but if it can only discharge at 3 kW it will not independently cover a 7 kW EV charger plus normal household loads. Conversely, installing a very high-power battery has little value if the energy and tariff strategy never needs that output.

For solar battery storage, we also check reserve settings, backup architecture, grid charging and manufacturer limits. MCS MIS 3012 treats storage as a designed system, including power-conversion equipment, controls, commissioning and handover.

Step 6: Choose an EV Charging Strategy, Not Just a Charger

An EV charger can be a large controllable load. We want to know when the car is connected, how much energy it needs before the next journey and whether the customer prefers solar matching, overnight cheap-rate charging or a mixture.

Our EV charger installation can be coordinated with solar and battery controls where the selected equipment supports it. The Electric Vehicles (Smart Charge Points) Regulations require relevant private charge points sold in Great Britain for domestic or workplace use to have smart functionality, including the ability to respond to signals and default off-peak charging behaviour.

Solar Diversion to an EV Needs Realistic Expectations

A 7 kW charger does not mean the solar array must produce 7 kW before the car can receive useful solar energy. Smart charging can reduce or vary charge power where the car, charger and control method support it. Equally, a small winter PV surplus will not fully charge a large EV battery simply because a solar mode is enabled.

We explain the likely energy contribution across seasons. In summer, daytime home charging can absorb substantial solar. In winter, overnight tariff charging may do more of the work. The system should be configured for the customer's actual driving pattern.

Step 7: Check the Incoming Supply and Load Management

Solar generation can reduce net import, but it does not make the electrical supply irrelevant. At night the EV may charge when PV is zero; the battery may be charging from the grid at the same time; electric cooking or a heat pump may also be operating.

We assess the main protective device, distribution board and the combined demand. Where load management is required, the charger or control system can reduce charging power to keep the property within an agreed limit.

Step 8: Establish the DNO Route for the Complete Generation System

Solar and battery power-conversion equipment can both affect the generation connection. The March 2025 GB connection guide distinguishes G98 systems up to the 16 A per phase registered-capacity threshold from larger G99 systems. We assess aggregate generation rather than assuming a battery is invisible to the network because it also consumes electricity.

Where the design needs DNO approval before connection, we deal with that at the appropriate stage rather than installing first and asking later. If export limitation is part of the solution, the controls and settings become part of commissioning.

Step 9: Check Building and EV Infrastructure Requirements

For new buildings and major renovations in England, Approved Document S provides guidance on electric vehicle charging infrastructure under Part S of the Building Regulations. It is not a universal rule for every retrofit driveway, but it is important when solar, batteries and EV infrastructure are being planned as part of a wider building project.

Building work can also bring structural, electrical and energy-efficiency requirements into the programme. We coordinate our part of the project with the applicable designer, contractor and building-control process rather than treating renewable equipment as outside the building design.

Step 10: Confirm Equipment and Documentation Before Ordering

We want the customer to know what products are being proposed. Equipment datasheets and system information are part of making an informed decision, and the final design should be based on the actual models that will be installed.

If product availability changes, we do not accept an arbitrary substitute just because the replacement has similar wattage. Module current, inverter inputs, battery compatibility, charger features, warranty and mounting dimensions can all affect the design.

Step 11: Coordinate Scaffold, Solar, Battery and Charger Works

Our admin and project workflow coordinates equipment, access and installation scheduling so the trades are not working as disconnected visits. The exact sequence depends on the site. Roof work and scaffold may begin first, while battery and charger preparation can happen around the electrical programme.

We also plan any necessary shutdowns. A customer should know when power may be interrupted and what part of the property will be unavailable.

Step 12: Commission Each Technology and the Interaction Between Them

Commissioning is not complete when each device powers on independently. We check the solar inverter, battery, EV charger, metering and monitoring as an integrated system. CT orientation, energy-meter readings and control logic are particularly important because incorrect measurement can make a battery charge or discharge at the wrong time.

Where applicable, we confirm grid and export settings, battery reserve, charging schedules and EV load management. The completed monitoring should show energy flows that make sense.

Step 13: Handover and Explain the System

We provide the applicable installation and equipment documentation and explain how the customer uses the monitoring, isolates equipment, changes normal schedules and recognises faults. For smart tariffs, we also explain which settings the customer may need to review if the supplier changes its tariff windows.

The customer does not need to become an engineer, but they should know whether the battery is meant to charge overnight, whether backup reserve is enabled and how to tell if the EV charger is being limited.

Step 14: Follow Real Performance After Installation

Once the system is operating, monitoring shows whether the design assumptions match real life. EV mileage can change. People work from home more or less. A new tariff can make a different battery schedule attractive. Solar generation varies with weather.

We see the installed system as an energy asset that can be adjusted within its technical limits rather than a configuration that should never be revisited.

Our View: Integrate the Decisions Before You Integrate the Hardware

The strongest solar-battery-EV installations are designed from the same set of energy data. We know what the roof can produce, what the home consumes, how much the battery can move, when the EV needs energy and what the network connection allows.

That is far more useful than buying three products separately and hoping their apps create an energy strategy afterwards.