A solar inverter is the working heart of a solar PV system. Your panels generate direct current (DC) electricity, but your property uses alternating current (AC). A proper guide to solar inverter installation therefore starts with more than choosing a unit and fixing it to a wall. It involves electrical design, safe cable routes, suitable protection, network approval and thorough testing before the system is put into service.
For homeowners, landlords and businesses in Plymouth and across Devon and Cornwall, getting these details right protects the property, supports reliable generation and avoids costly alterations later.
What does a solar inverter do?
The inverter converts electricity from solar panels into usable power for your home or business. It also monitors the output of the array and responds to changes in sunlight, demand and grid conditions. Depending on the system, it may communicate with an app, direct surplus energy to a battery or hot water diverter, and safely shut down if there is a fault on the electricity network.
This makes the inverter a key electrical component, not simply an accessory. A poor location, undersized cable, unsuitable consumer unit connection or incorrect settings can affect performance and, more importantly, safety.
Most domestic systems use either a string inverter or microinverters. A string inverter is usually mounted near the consumer unit, garage or utility area and manages a group of panels together. Microinverters are fitted at panel level, which can help where roof sections face different directions or experience regular shading. The right option depends on the roof layout, expected generation, budget and future plans for battery storage.
Planning a solar inverter installation
A site survey should come before any installation work. The installer needs to understand the existing electrical supply, the condition and capacity of the consumer unit, the route from roof to inverter, earthing arrangements and where the system will connect to the property.
In an older home, the electrical installation may need attention before solar can be connected safely. For example, a dated fuse board, inadequate earthing or signs of previous alteration may need rectification first. This is not unnecessary extra work. Solar generation introduces a new source of power to the installation, so the protective devices and connections must be suitable for it.
The proposed inverter location also needs proper consideration. It should be accessible for maintenance, protected from accidental damage and positioned where it will not overheat. Garages, utility rooms and other sheltered areas are common choices, but each property is different. A loft can appear convenient, yet high summer temperatures and restricted access can shorten equipment life and make servicing harder.
The following points are normally considered during planning:
- inverter rating and compatibility with the proposed solar array;
- battery-ready capability if storage may be added later;
- DC and AC cable routes, including fire-safe penetrations through the building fabric;
- ventilation, weather protection and clear working space around equipment;
- consumer unit capacity, isolation points and surge protection; and
- the electricity network operator requirements for the planned generation capacity.
Good planning keeps the visible installation neat while ensuring the system remains practical to inspect, test and maintain.
Network approval and electrical compliance
A solar PV system cannot simply be connected to the mains without the right process. Small domestic installations are commonly notified to the local Distribution Network Operator under the G98 process. Larger systems, or systems that exceed the relevant export limits, may need approval under G99 before installation.
Your installer should establish which route applies before the work starts. This is particularly relevant where a property already has generation, a battery system, an EV charger with energy management, or a three-phase supply. Commercial sites often need a more detailed assessment because their demand profile, supply arrangement and existing electrical equipment can be more complex.
The electrical work must comply with current BS 7671 Wiring Regulations. That includes selecting suitable cables, installing correct isolation and overcurrent protection, confirming earthing arrangements and applying clear labels. The system should also be tested and certified on completion.
Where solar PV is part of a wider project, coordination matters. A consumer unit upgrade, EV charger, battery and solar array should not be treated as unrelated additions. Looking at the whole installation can prevent unnecessary duplication and help ensure the available supply capacity is managed sensibly.
The solar inverter installation process
Once the design is agreed and any required network process is in hand, the electrical installation can begin. The exact sequence varies by property and whether the panels are being fitted at the same time, but the principles remain the same.
First, the installer confirms safe isolation arrangements and prepares the cable routes. DC cables from the roof array are routed to the inverter using appropriate containment and protection. Any entry through the roof or external wall must be sealed carefully to maintain weather resistance and reduce the risk of damage to cables over time.
The inverter is then securely mounted in its planned position. It must be fixed to a suitable surface, with enough clearance around it for cooling and future access. DC isolators, where required by the design, and AC isolation are installed so that the system can be safely disconnected for maintenance or in an emergency.
The AC side of the inverter is connected to the consumer unit or distribution board through dedicated protective equipment. This is where professional design is essential. Devices must be selected for the characteristics of the supply and the inverter, rather than chosen on a one-size-fits-all basis. Surge protection may also be needed, particularly where the risk assessment and installation arrangement call for it.
Finally, the installer configures the inverter. This can include setting the correct country and grid parameters, connecting monitoring equipment and confirming any export limitation controls. Incorrect configuration can lead to nuisance shutdowns, lost generation or non-compliance with network requirements.
Testing, commissioning and handover
Switching an inverter on is not the same as commissioning a solar PV system. Before the system is energised, electrical tests are carried out to confirm that circuits, protective measures and connections are safe. The installer will also check polarity, insulation resistance, continuity and the operation of isolators and protective devices as appropriate to the system design.
Commissioning then confirms that the inverter starts correctly, communicates with the monitoring platform and responds properly to the grid. Generation readings will vary with weather and time of day, so a modest output on an overcast Devon morning does not necessarily indicate a problem. What matters is that the system performs as designed and that measured values are sensible for the conditions.
At handover, the property owner should receive the relevant certification, commissioning information, equipment manuals and details of any network notification or approval. Keep these documents with your electrical records. They can be useful for maintenance, insurance queries, selling the property and future additions such as a battery.
Common mistakes to avoid
The most expensive mistakes often happen before the inverter is fitted. Choosing equipment solely on its headline price can leave little allowance for cable containment, electrical upgrades, correct protection or a practical location. A cheaper unit may also be a false economy if it cannot support the battery or monitoring features you expect to need later.
Another common issue is treating the inverter as an afterthought. Panels may be planned carefully while the inverter ends up in a hot, inaccessible loft or on an exposed external wall without suitable protection. Discuss the location early, including the route to the consumer unit and how future servicing will be carried out.
DIY work is also a poor fit for this type of installation. Solar PV combines high-voltage DC circuits with a connection to the public electricity network. The work needs competent design, testing and certification, and it may involve notification to the network operator. Using a qualified electrical contractor gives you a clear route to safe, compliant work and accountable documentation.
When should you ask for electrical advice?
Ask for advice before committing to a solar quote if your consumer unit is older, your lights flicker, you have recurring tripping, or you are planning other major electrical additions. The same applies to landlords considering solar for a rental property and businesses looking to offset daytime energy use. The roof may be suitable, but the electrical infrastructure still needs to be ready.
Goodwin Electrical can assess the electrical side of a solar PV project, including consumer unit suitability, protection, connection work and certification. Clear advice at the outset gives you a safer installation and a system that is easier to live with for years to come.
The best solar inverter installation is rarely the one with the quickest route from roof to fuse board. It is the one that is properly designed for the property, documented clearly and installed so that future maintenance is straightforward.