A solar quote can look simple until you reach the inverter specification. Panels produce direct-current electricity, but your home or business needs alternating current. The inverter makes that conversion possible, and the choice between string versus microinverters can affect system cost, energy yield, monitoring and future maintenance.
Neither option is automatically better. The right answer depends on your roof, how much shade it receives, the number of roof aspects involved and what you want from the system over the years ahead. A good solar design starts with those details, rather than fitting the most expensive equipment or relying on a one-size-fits-all package.
What is a string inverter?
A string inverter is a single central unit, usually installed near your consumer unit, in a utility room, garage or other suitable protected location. Your solar panels are connected in groups, known as strings, and the inverter converts the combined output into usable electricity.
It is the most common arrangement for UK domestic solar installations, particularly where panels sit on one clear, unshaded roof slope. Modern string inverters are efficient, reliable and often compatible with battery storage either immediately or as a later addition. Many also offer monitoring through an app, allowing you to see overall generation and household consumption when the required metering equipment is included.
The key consideration is that panels in the same string are electrically linked. If one panel performs less well because of shade, dirt, a chimney shadow or a different orientation, it can reduce the output of other panels in that string. This effect is not always as dramatic as it is made out to be, as quality inverters use maximum power point tracking to manage strings intelligently. But it matters on more complex roofs.
What are microinverters?
Microinverters are small inverters fitted beneath, or very close to, each solar panel. Instead of sending DC power from a whole string to one central inverter, each panel converts its own output to AC power on the roof.
This means every panel works independently. If a panel is temporarily shaded by a tree, vent pipe or neighbouring property, the unaffected panels can continue operating at their own optimum level. Microinverters also provide panel-level monitoring, so you can see the performance of individual panels rather than only the system total.
For roofs with several orientations, partial shading or awkward layouts, that independence can be genuinely useful. It can also make a future expansion simpler, provided the system design, electrical capacity and planning requirements allow for it.
However, microinverters are not a free performance upgrade. They cost more than a standard string inverter arrangement, and there are more electronic components installed on the roof. Although reputable equipment is designed for this environment and commonly carries long warranties, access for a future replacement may be more involved than changing a wall-mounted string inverter.
String versus microinverters: the practical differences
The most useful comparison is not simply efficiency against price. Both technologies can deliver excellent results when properly designed and installed. The practical differences come down to your property.
Shading and roof layout
Microinverters are often well suited to roofs affected by regular, uneven shade. Examples include a chimney that shades only a few panels in the morning, a dormer window, satellite equipment or nearby trees that affect part of the array at certain times of year.
They can also work well where panels are spread across east, west, south and even smaller secondary roof areas. Each panel has its own conversion equipment, so different orientations are less of a constraint.
A string inverter can still be an excellent solution for moderate complexity. Systems can use separate strings or multiple MPPT inputs, allowing different roof slopes to operate independently. Panel optimisers may also be used with some string inverter designs. These are fitted at panel level to manage DC output before it reaches the central inverter, offering some of the shade-management benefits of microinverters without converting electricity to AC at every panel.
The point is to measure, not guess. A site survey should assess roof angles, available space, obstructions and likely seasonal shading. A bare tree in summer photographs may create far more shade once it is in leaf, while a chimney shadow changes length throughout the year.
Cost and value
For a straightforward south-facing roof with little or no shade, a string inverter will usually provide the strongest value. It has fewer components, lower equipment and installation costs, and can generate a very good return through reduced electricity purchases and export payments.
Microinverters typically require a larger upfront investment. The additional cost may be justified where they recover generation that a basic string layout would lose, or where panel-level monitoring gives the owner useful confidence in a complicated system. On a simple roof, however, the extra spend may not produce enough additional electricity to pay back quickly.
For commercial sites, the calculation is similar but the scale is larger. A shaded warehouse roof, multi-pitch office building or estate of smaller buildings may benefit from a more distributed design. A large, clear industrial roof may be better served by carefully planned string inverters. System size, access, cable routes, export arrangements and operational needs all affect the decision.
Monitoring and fault finding
Most modern solar systems offer app-based monitoring. With a string inverter, you will normally see total generation and, where energy meters are fitted, how much power the property imports, exports and uses directly.
Microinverters offer more detailed panel-by-panel information. This can identify an underperforming panel, a localised shading issue or a fault more quickly. For owners who like close visibility, or for properties where panels are difficult to inspect, that is a clear advantage.
There is a sensible middle ground. Detailed data is helpful, but it should not distract from the figures that matter most: how much solar electricity you use on site, how much you buy from the grid, and whether your battery and tariff are working together effectively.
Battery storage and future plans
If battery storage is part of the plan, discuss it before the solar system is designed. Some string inverter systems are hybrid, meaning one inverter can manage both solar panels and a battery. Others are battery-ready, or can be coupled with a separate battery inverter later.
Microinverter systems produce AC electricity at the panel, so batteries are commonly added as AC-coupled systems. This can be a flexible arrangement, especially for adding storage later, but the equipment selection must be planned carefully to avoid unnecessary conversion losses and to ensure the system works as intended during normal operation.
A battery should not be chosen solely because it is available. Its size should reflect your daytime generation, evening usage, electricity tariff and aims, whether that is lower bills, backup capability where suitable, or greater use of self-generated energy.
Questions worth asking before you choose
A clear proposal should explain why a particular inverter has been specified for your roof. Ask how shading has been assessed, whether panels are on more than one roof aspect, what monitoring is included and how the design supports a future battery or additional panels.
It is also worth asking about warranties, likely maintenance access and who will handle commissioning, testing, certification and aftercare. The inverter is a critical part of your solar installation, so it should be specified with the same care as the panels, mounting system and electrical protection.
At Evolve Electrical Contractors, solar designs are based on a proper survey and your expected electricity use, not a standard package. MCS-certified installation, compliant electrical work and clear handover information help ensure the system is done right the first time.
Choose the design that suits the roof
For many homes, a quality string inverter is the sensible, cost-effective choice. For a roof with frequent partial shade, varied orientations or a need for detailed panel monitoring, microinverters may earn their additional cost. In between, a string inverter with separate MPPTs or optimisers can be the right compromise.
The best solar system is the one that fits the property, your budget and the way you use electricity. A careful survey and honest design conversation will give you a far better result than choosing an inverter type from a headline claim alone.