The main solar inverter types are string inverters, microinverters, power optimisers and hybrid inverters. Most homeowners with a simple, unshaded roof do well with a string inverter or, if battery storage is planned, a hybrid unit. Shaded or complex roofs usually justify the extra cost of microinverters or optimisers, which work at panel level instead of treating the whole array as one unit.
TL;DR:
- String inverters are most cost-effective and suitable for simple, unshaded roofs, but shading can significantly reduce their efficiency.
- Microinverters offer panel-level optimization, ideal for shaded or complex roofs, and have longer warranties but come with higher upfront costs.
- Power optimizers bridge the gap by providing panel-level MPPT at a lower cost than microinverters, but they still rely on a central inverter that can fail.
- Hybrid inverters combine solar and battery management functions, simplifying installation for those with storage plans but limiting future battery brand options.
- Proper site surveys, inverter specifications, and understanding grid connection rules are essential to choosing the most suitable inverter architecture for your roof.
Table of Contents
- Getting to grips with the main inverter types
- String inverters: the simple, established default
- Microinverters: panel-level control for tricky roofs
- Power optimisers: a middle path between string and micro
- Hybrid inverters: built for solar-plus-storage
- The technical specs that actually affect your bills
- How your inverter choice shapes battery pairing
- Grid connection rules you need to check before installing
- A step-by-step checklist for choosing your inverter
- What a proper installation actually involves
- Why the cheapest inverter rarely wins long term
- How Smart Home Technical can help you decide
- Sources
- FAQ
Getting to grips with the main inverter types
Every solar system needs an inverter to turn the direct current your panels produce into the alternating current your home actually uses. The four types differ mainly in where that conversion happens and how much of the array each device controls.
- String inverter: one central box converts power from a whole “string” of panels wired together, best for simple, unshaded roofs on a budget.
- Microinverter: a small inverter fitted to each panel, best for shaded or complex roofs where every bit of yield matters.
- Power optimiser: a panel-level device that conditions the current before sending it to a central inverter, a middle ground between string and micro systems.
- Hybrid inverter: manages solar generation and battery charging in one unit, best for homeowners planning storage now or soon.
Domestic systems are almost always single-phase in the UK, though larger commercial or some newer detached homes may use three-phase equipment. Power ratings for typical homes usually fall in the 3 to 6 kilowatt range, matched closely to the size of the panel array. How you plan to add batteries and which grid connection rules apply both shape which type makes sense, and both get proper treatment further down this article.
String inverters: the simple, established default
A string inverter sits centrally, often in a garage or utility room, and takes the combined DC output from one or more strings of panels wired in series. It performs maximum power point tracking, or MPPT, across the whole string, then converts that to AC for the home. It’s the layout that has powered the majority of domestic solar installations for years, largely because it’s straightforward to design, install and maintain.
The appeal is cost and simplicity. A single inverter is cheaper to buy than an equivalent number of microinverters, easier to access for servicing, and its failure mode is obvious: if it stops working, you’ll know, because the whole system stops producing.
- Lower cost: fewer components mean a lower price per installed kilowatt.
- Simple design: one box to install, wire and maintain.
- Easy replacement: swapping a faulty unit is a contained, well-understood job.
- Shading sensitivity: one shaded panel can drag down the output of the entire string.
- Single point of failure: if the inverter fails, the whole array stops generating until it’s fixed.
String inverters suit a south or south-west facing roof with no chimneys, dormers or overhanging trees casting shadows across panels at different times of day. They pair happily with AC-coupled battery systems added later, and most manufacturers offer optional monitoring add-ons, though these tend to be less granular than the panel-by-panel data you get with microinverters.
Microinverters: panel-level control for tricky roofs
A microinverter is fitted directly behind each panel and performs MPPT and DC-to-AC conversion at that single panel, rather than across a whole string. That means each panel operates independently: if one is shaded, dirty or facing a slightly different direction, it doesn’t drag down its neighbours.
This independence is the main selling point. On a roof with a dormer window, a chimney or a nearby tree that shades part of the array for a few hours a day, microinverters can recover output that a string system would lose across the whole string. They also remove the single-point-failure risk: one failed microinverter affects only that panel, and the rest of the array keeps producing.
- Per-panel optimisation: each panel is tracked and converted independently, reducing shading losses.
- Resilience: a single unit failing takes out one panel, not the whole system.
- Easier expansion: adding panels later is simpler because each one is a self-contained unit.
- Higher upfront cost: more individual components mean a higher price per installed kilowatt.
- Servicing complexity: accessing a microinverter mounted under a panel can mean working at height, unlike a garage-mounted string inverter.
Warranty terms often run longer than for string inverters, which is worth factoring into lifetime cost even though the sticker price is higher. Microinverters make most sense on roofs with partial shading, mixed orientations (an east-west split roof, for example) or where you expect to add panels in stages rather than fit the whole array at once.
Power optimisers: a middle path between string and micro
Power optimisers sit between the two approaches above. Each panel gets its own optimiser, which performs panel-level MPPT and conditions the DC output, but the actual DC-to-AC conversion still happens at a central inverter, much like a string system. You get most of the shading resilience of microinverters without paying for a full inverter at every panel.
- Architecture: one optimiser per panel feeds a shared central inverter, splitting the difference between string and micro designs.
- Cost and performance: typically cheaper than a full microinverter setup, while outperforming a plain string system on shaded or mixed-orientation roofs.
- Central point of conversion: the main inverter can still fail as a single unit, though panel-level monitoring survives even then.
Optimisers are a pragmatic choice for a roof that’s mostly clear but has one or two problem panels, letting you address the shaded spots without redesigning the whole system around microinverters.
Hybrid inverters: built for solar-plus-storage
A hybrid inverter combines solar inverter and battery management functions in a single unit. It handles DC power from the panels, charges and discharges a battery, and converts everything to AC for the home, and many models can also provide islanding, keeping essential circuits running during a grid outage.
The main benefit is integration: one unit, one set of firmware, one monitoring app, rather than juggling a separate solar inverter and battery inverter with their own settings and warranties. That simplicity can mean a tidier installation and fewer points where two systems need to talk to each other correctly.
- Battery management: charge and discharge cycles are handled by the same unit that runs the solar side.
- Islanding capability: many hybrid units can power the home during a grid outage where the battery has charge.
- Integration: fewer components to install, wire and monitor compared with separate solar and battery inverters.
- Vendor lock-in: batteries from a different manufacturer may not be compatible, limiting future choices.
Hybrid inverters reduce installation complexity when you know you want a battery from the outset, or plan to add one within the inverter’s working life. If you’re not sure about storage, or want the flexibility to choose any battery brand later, a separate string or micro system paired with a standalone battery inverter down the line keeps your options open, at the cost of a slightly more complex installation.
The technical specs that actually affect your bills
Beyond the four broad types, a handful of specifications determine how much electricity your system actually produces and how long it lasts.
MPPT quality varies between inverters. Conventional perturb-and-observe algorithms are the industry standard because they’re cheap and reliable, but benchmarked research on MPPT algorithms shows that more advanced intelligent methods, such as artificial neural networks, can reach higher theoretical tracking efficiencies, reported around 98.6% in that review, at the cost of greater complexity. That gap matters most on roofs with partial shading or unusual layouts, where a conventional algorithm loses more potential yield.
Sizing matters too. Installers commonly size the inverter’s rated power slightly below the array’s peak DC capacity, a practice called oversizing the array or undersizing the inverter, because panels rarely hit their rated output simultaneously. Push this too far and you get clipping, where the inverter caps output during the sunniest hours, so ask your installer to explain the ratio they’ve chosen for your roof.
- MPPT approach: conventional methods are cheaper; advanced methods help more on shaded or complex arrays.
- Power rating and phase: match the inverter’s AC output to your home’s single-phase or three-phase supply.
- Monitoring: look for an app or platform that shows panel-level or string-level data, not just a single daily total.
- Warranty length: terms vary significantly by manufacturer and inverter type, so compare like for like.
Panel efficiency and inverter sizing interact closely, and it’s worth reading up on how panel efficiency affects real-world output before settling on an inverter rating.
Pro Tip: Ask any installer to show you the manufacturer’s datasheet for the specific inverter model they’re quoting, not just a brochure figure, since real-world efficiency can differ from headline numbers.
How your inverter choice shapes battery pairing
Batteries connect to a solar system in one of two ways. AC-coupled setups use a separate battery inverter that talks to your existing solar inverter over the home’s AC wiring, useful for retrofitting a battery onto a system you already own. DC-coupled setups, typically built around a hybrid inverter, keep the battery on the DC side, which can be slightly more efficient because power is converted fewer times.
- AC-coupled: flexible, works with almost any existing inverter, simple to retrofit later.
- DC-coupled: usually via a hybrid inverter, marginally more efficient, but ties the battery to that inverter’s ecosystem.
- Sizing: the battery’s charge and discharge power should be matched to typical household demand, not just its total storage capacity.
Adding a battery raises self-consumption and cuts reliance on daytime export, though the Energy Saving Trust notes that the financial case depends heavily on household demand and export tariffs, and works out best in homes with high demand or a heat pump. Homes planning a staged upgrade, solar now and a battery later, often do well choosing an inverter that’s explicitly battery-ready from the outset rather than retrofitting compatibility afterwards, a point covered in more detail in guidance on how solar and battery pairing cuts night-time import costs.
Grid connection rules you need to check before installing
Every UK domestic solar or battery installation has to connect to the network under one of two engineering recommendations. EREC G98 applies to fully type-tested micro-generators up to 16A per phase, which covers most typical domestic solar and battery combinations. Systems above that threshold, or larger generation and storage setups, fall under EREC G99, which carries more detailed connection and testing procedures.
- G98: fully type-tested equipment up to 16A per phase, the pathway most single-property solar and battery jobs use.
- G99: required above that threshold or for larger combined generation and storage capacity.
- MCS certification: an MCS-certified installer handles the paperwork correctly and ensures equipment meets the type-testing standards these recommendations require.
Regulation in this area keeps evolving. Ofgem and the Energy Networks Association have introduced changes requiring storage systems to support Limited Frequency Sensitive Mode, Underfrequency, known as LFSM-U, alongside updates to how micro-generation and storage connections are processed together. It’s worth asking any installer directly whether the inverter and battery combination they’re proposing already meets current LFSM-U and connection requirements, since firmware and settings, not just hardware, can be affected. Homeowners near the 16A threshold, particularly once storage capacity is added to solar capacity, should ask specifically which pathway applies, a distinction covered in more depth in guidance on G98 versus G99 for domestic installs.
A step-by-step checklist for choosing your inverter
Working through inverter choice in order, rather than picking a type first, tends to produce a better-fitted system.
- Get a proper site survey: shading, roof orientation and available space all affect which architecture makes sense.
- Decide your battery plan: know now, soon or never shapes whether a hybrid inverter earns its keep.
- Match architecture to your roof: simple, unshaded roofs suit string inverters; shaded or mixed-orientation roofs suit micro or optimiser systems.
- Check warranties and monitoring: compare terms across the specific models quoted, not just the inverter type.
- Compare quotes on the same basis: ask each installer to specify inverter make, model and rated power so you’re comparing like for like.
When you’re talking to installers, ask directly about their MCS certification, how they’ll handle earthing and cut-out checks, what yield they expect from your specific roof, and how warranty claims are handled if something fails. Be wary of any quote that arrives without a site visit, or that makes no mention of G98, G99 or MCS certification at all, since that usually signals a generic estimate rather than a design suited to your roof.
What a proper installation actually involves
A competent installer starts with a site survey covering roof orientation, shading and existing electrical capacity, then designs the string layout or panel-level architecture around what that survey reveals. Earthing arrangements and cut-out checks come next, followed by the paperwork needed for G98 or G99 notification, which an MCS-certified installer handles as a matter of course.
Common constraints, a shaded chimney, an odd roof pitch, limited loft space for cabling, usually have a straightforward fix once they’re spotted early, whether that’s repositioning a string, adding an optimiser to one problem panel, or choosing a different inverter mounting location. When comparing installers, checking for MCS and NICEIC accreditation and asking how they’ve handled similar roof layouts before gives a realistic sense of what to expect.
Why the cheapest inverter rarely wins long term
The inverter market rewards low headline prices, but the unit that costs least upfront often isn’t the one that earns its keep over 20 or more years on a roof. Homeowners underestimate how much their electricity habits will change: an EV charger or a heat pump added in three years’ time can shift a system from comfortably sized to undersized overnight.
Choosing hybrid-ready hardware now, even before a battery is bought, tends to cost little extra and keeps options open. Reliability and installer competence matter more than shaving a small amount off the initial quote, because a failed inverter or a badly documented connection causes far more disruption than the saving was ever worth.
— Simon
How Smart Home Technical can help you decide
Working out which inverter architecture suits your roof is easier with a proper site survey rather than guesswork from a brochure. Professional electricians can carry out solar panel installation, battery storage integration and EV charger installation, and walk you through string, micro, optimiser and hybrid options against your actual roof, shading and future plans, whether that includes an EV or a heat pump.
If you already have a system and want ongoing peace of mind, the Solar & Battery Service & Maintenance Plan costs £175 per year and covers scheduled checks on installed solar and battery equipment. For a new installation, get in touch through the solar installations page to arrange a survey and a quote based on your roof, not a generic estimate.
Sources
FAQ
What are the different types of solar inverters?
The main types are string inverters, microinverters, power optimisers and hybrid inverters. String inverters convert power from a whole array centrally, microinverters and optimisers work at panel level, and hybrid inverters add battery management to the solar conversion function.
What are the three main types of inverters?
When people say “three main types,” they usually mean string inverters, microinverters and power optimisers, treating hybrid inverters as a variant built around one of these architectures. Each differs mainly in whether MPPT and conversion happen centrally, per panel, or at a panel-level device feeding a central inverter.
Which type of solar inverter is better, PWM or MPPT?
MPPT controllers track the panel’s maximum power point continuously and generally deliver more usable energy than simpler PWM controllers, which is why MPPT is the standard for grid-connected home solar systems. PWM technology is mostly found in smaller off-grid or specialist setups rather than typical rooftop installations.
What type of inverter is best for solar panels?
There isn’t one best type for every roof: a string inverter suits a simple, unshaded roof on a budget, while microinverters or optimisers suit shaded or complex roofs, and a hybrid inverter suits homeowners planning battery storage. The right choice depends on your roof’s shading, your budget and whether storage is part of the plan.
