The inverter is the single most consequential component decision in a commercial solar system. It determines monitoring quality, fault tolerance, replacement risk, warranty exposure and — at scale — a meaningful percentage of total capex. The right inverter choice depends on system size, shading, monitoring needs and budget. This page lays out the seven Tier 1 brands we routinely specify (SolarEdge, SMA, Fronius, Huawei, Solis, Sungrow, GoodWe), the string-vs-central trade-off, the DC:AC sizing logic, warranty options and how G98/G99 type-test certification works.
The seven Tier 1 inverter brands we specify
The UK commercial market has narrowed over the last decade to a stable group of high-quality brands. Below is what we specify and where each shines.
SolarEdge — module-level optimisation, premium monitoring
SolarEdge HD-Wave inverters paired with per-panel power optimisers are our default specification on any roof with shading complexity, mixed-orientation panels, or where the customer values granular monitoring. The HD-Wave inverter operates at 99% European efficiency and is materially smaller and lighter than competitors. Power optimisers report at module level, so the SolarEdge Monitoring platform shows generation per panel — invaluable for diagnosing soiling, shading or module faults years into the operating life. Standard warranty 12 years inverter, 25 years optimiser. Premium price point but justified on shaded sites.
SMA — German engineering, long-haul reliability
SMA Sunny Tripower CORE2 (the current commercial line) is the brand we specify when the customer prioritises long-term reliability over feature list. SMA has the longest commercial track record of any Tier 1 brand, German engineering rigour shows in the build quality and the operating life data, Sunny Portal monitoring is solid (though module-level visibility requires Tigo TS4 add-ons). Standard 10-year warranty, extendable to 25. Higher price point than Solis or GoodWe but the operating-life data justifies it on systems where the customer plans to hold the asset for the full 25 years.
Fronius Tauro — Austrian, modular, weather-rated
Fronius Tauro is an Austrian-engineered modular commercial inverter line. The standout features are external IP65 weather-rating (so the inverter can be installed outdoors with no enclosure required) and modular replacement (a faulty power module can be swapped on-site without taking the whole inverter offline). 10-year standard warranty, 25-year extendable. Premium tier — competing directly with SMA on quality positioning.
Huawei FusionSolar — high-efficiency, smart features
Huawei SUN2000 commercial inverters offer some of the highest efficiency figures in the market (98.6% peak European efficiency on the latest generation), strong monitoring through the FusionSolar platform, and smart features including AI-based string-level diagnostics. Pricing is competitive against SMA / Fronius and below SolarEdge. Strong choice for unshaded large-scale projects (above 200 kW) where central or string-multi configurations apply. 10-year standard warranty.
Solis — cost-effective, strong UK distributor support
Solis (Ginlong Technologies) is the value-end Tier 1 brand. Build quality is genuine Tier 1, monitoring is functional through SolisCloud, UK distributor support is strong (Segen, Solar Trade Sales, BHA Solar) which matters for warranty claim turnaround. Pricing per kW is materially lower than SolarEdge or SMA. Right choice for cost-sensitive mid-market commercial projects (50-300 kW) on simple unshaded roofs. 10-year standard warranty extendable.
Sungrow — utility-scale option
Sungrow is the dominant utility-scale inverter brand globally, with significant UK adoption above 500 kW. Central inverter offerings (1500 V DC, 100-300 kW per unit) deliver the lowest per-kW cost on large arrays. String inverters (Sungrow SG series) compete with Huawei at the 50-200 kW band. Strong choice for ground-mount, solar carport, and very large rooftop projects. 10-year standard warranty.
GoodWe — mid-market, broad product range
GoodWe sits between Solis and Huawei on price-quality positioning. Particularly strong in hybrid inverter configurations where battery storage is part of the design. SEMS Portal monitoring is competent. Warranty 10 years standard. Right choice for mid-market commercial projects where a hybrid PV-plus-battery configuration is in scope from day one.
String inverters vs central inverters
Below 200 kW string inverters dominate UK commercial PV. Modern Tier 1 string inverters (SolarEdge HD-Wave, SMA Sunny Tripower CORE2, Fronius Tauro, Huawei SUN2000, Solis, GoodWe) range 30-150 kW per unit. A 250 kW system might use two 125 kW string inverters; a 500 kW system might use four 125 kW units. String inverter advantages: fault tolerance (one inverter failure takes only its share of capacity offline), simpler replacement (swap a single unit, no specialist tooling), better fit for irregular roof layouts (separate inverters per roof segment), no civil works required (wall-mount inside switch room or outside on Fronius IP65).
Above 200-500 kW central inverters become cost-competitive. A single 500 kW central inverter (Huawei, Sungrow) costs less per kW than four 125 kW string inverters and occupies less space, but takes the whole system offline if it fails. Central inverters are typical for ground-mount, solar carport and utility-scale rooftop above 1 MW. We default to string-multi configurations (multiple parallel string inverters) up to about 1 MW, with central inverters for larger arrays.
DC:AC sizing ratio
The DC:AC ratio is the array DC nameplate divided by the inverter AC output. A 110 kW DC array on a 100 kW AC inverter is 1.10; a 130 kW DC array on the same inverter is 1.30. Why oversize? Because PV arrays only briefly hit nameplate output — most of the time they run well below rated. Oversizing the array against the inverter captures more morning and evening generation (when DC output is above zero but well below peak) at the cost of clipping peak summer midday output (when DC briefly exceeds inverter AC capacity, the inverter caps output and the surplus is lost).
For UK climate the sweet spot is 1.15-1.25. Below 1.10 ratio you are under-using the inverter (paying for capacity you rarely use). Above 1.30 ratio summer clipping becomes meaningful and starts to erode IRR. Inverter manufacturers typically allow up to 1.5 ratio in spec — but allowable does not mean optimal. We model PVSyst against multiple ratios and pick the one that maximises lifetime IRR.
Inverter warranty options
Standard commercial inverter warranty is 10 years across most Tier 1 brands. SolarEdge offers 12 years standard. Extended warranty options (typically 15, 20 or 25 years) are available from manufacturer at additional cost — typical 2026 pricing is £150-£400 per kW for a 25-year extension. We model the financial case on every project: extension cost vs probability of warranted failure inside the extension period vs replacement cost at year 12-15 if not extended. The answer varies by site — generally extension makes sense on premium SolarEdge and SMA installations, less often on Solis and GoodWe where the price differential is materially smaller and a planned year-12 replacement is the rational baseline.
G98 and G99 type-test approval
Every UK commercial inverter must hold a current G99 type-test certificate (or G98 for under 17 kW per phase systems) issued under EREC G99 Issue 1 Amendment 9 — the 2026 standard. The certificate confirms the inverter has been tested by an accredited test laboratory against UK protection requirements: voltage and frequency trip envelopes, anti-islanding response, ROCOF and vector shift detection. Without current type-test certification, the inverter cannot be specified on a UK commercial PV install — DNO applications are rejected immediately.
Every brand we specify (SolarEdge, SMA, Fronius, Huawei, Solis, Sungrow, GoodWe) holds current type-test certification across their commercial product range. We check the Energy Networks Association type-test register at design stage to confirm the specific model proposed has current certification. Older inverter models sometimes drop off the register when the manufacturer moves to a new generation — the same model that was certified two years ago may no longer be approved today.
Inverter monitoring platforms compared
SolarEdge Monitoring is the strongest commercial monitoring platform — module-level data through the optimisers, granular fault diagnostics, mature mobile app, public API for integration with energy management systems. SMA Sunny Portal is solid for inverter-level data but module-level visibility requires Tigo TS4 add-ons. Fronius Solar.web is competent and increasingly feature-rich. Huawei FusionSolar is the most feature-rich behind SolarEdge — granular diagnostics, AI-based string-level alerts. Solis SolisCloud and GoodWe SEMS are functional and meet baseline monitoring needs but lack the depth of premium platforms. We weight monitoring quality heavily in inverter selection on systems where downtime cost is high (cold storage, data centres, manufacturing).
Battery hybrid considerations
Where battery storage is in scope, the inverter selection narrows. Hybrid inverters (single unit handling both PV and battery) include GoodWe ET, SolarEdge StorEdge, Solis Hybrid, Huawei LUNA. AC-coupled architectures (separate PV inverter + battery inverter) work with any PV inverter brand and offer more flexibility but at higher capex. We discuss the architecture choice at design stage. See our battery storage service page for the broader battery storage decision logic.
Useful authority links
The Energy Networks Association maintains the inverter type-test register: energynetworks.org. MCS certification standards include inverter approval criteria: mcscertified.com. Solar Energy UK publishes industry data and brand reviews: solarenergyuk.org.
Related decision pages
For the wider system efficiency picture see solar vs alternatives. For the maintenance approach that protects inverter warranty see commercial solar maintenance contract and our maintenance service. For commissioning that configures the inverter correctly see solar panel commissioning. For the warranty terms see commercial solar warranty. For the DNO type-test certification process see G98 application and G99 application. For the broader system design see commercial solar service and 100 kW solar systems. The hub for everything commercial solar is commercial solar PV.
Commercial solar inverters — common questions
What is the best inverter for commercial solar in the UK 2026?
There is no single best inverter — the right choice depends on system size, shading, monitoring requirements and budget. For shading-heavy or complex roofs we typically specify SolarEdge with HD-Wave inverters and module-level optimisers. For unshaded clean roofs we typically specify SMA Sunny Tripower CORE2 or Fronius Tauro for premium monitoring and longevity. For mid-market price-sensitive projects Solis or GoodWe deliver Tier 1 quality at competitive cost. Above 200 kW we routinely specify Huawei FusionSolar or Sungrow central inverters.
Should I use string inverters or central inverters?
Below 200 kW string inverters dominate — SolarEdge HD-Wave, SMA Sunny Tripower, Fronius Tauro, Huawei SUN2000, Solis, GoodWe. Above 200-500 kW central inverters (Huawei, Sungrow) become cost-competitive due to lower per-kW capex but reduce redundancy (single failure takes more capacity offline). String inverters offer better fault tolerance and simpler replacement; central inverters offer lower cost per kW. For utility-scale (above 1 MW) we typically default to central or string-multi configurations.
What is the right DC:AC sizing ratio for UK commercial solar?
A DC:AC ratio of 1.1-1.3 is standard for UK commercial PV in 2026. The ratio is the array DC nameplate divided by the inverter AC output. A 110 kW DC array with a 100 kW AC inverter is 1.1; a 130 kW DC array with the same inverter is 1.3. Higher ratios capture more morning and evening generation but clip peak summer output (when DC exceeds inverter capacity, the inverter caps output). UK climate makes 1.15-1.25 the typical sweet spot. Above 1.3 ratio significant clipping starts to erode the IRR.
How long is the standard inverter warranty?
Standard commercial inverter warranty is 10 years across most Tier 1 brands. Extended warranties (typically 15, 20 or 25 years) are available at additional cost — usually £150-£400 per kW for a 25-year extension. SolarEdge offers 12 years standard with 25-year extensions; SMA varies by model. We model the financial value of extension on every project — sometimes the answer is yes, often the answer is to budget for a planned year-12-15 replacement instead.
Are microinverters used in commercial solar?
Microinverters (Enphase) are common in residential but rare in commercial above 30 kW. The economics fail at scale — per-kW cost is materially higher than string inverters and central inverters, and the per-panel maintenance overhead at 100+ panels becomes operationally awkward. For shading-heavy commercial roofs, module-level optimisers (SolarEdge, Tigo TS4) deliver most of the microinverter benefit at materially lower cost per kW. We rarely specify microinverters above 30 kW.
Do all Tier 1 inverters hold G98 and G99 type-test certificates?
Yes — every brand we specify (SolarEdge, SMA, Fronius, Huawei, Solis, Sungrow, GoodWe) holds current G98 and G99 type-test certificates under EREC G99 Issue 1 Amendment 9 (the 2026 standard). Type-test certificates are essential for the DNO application — using an inverter without current certification fails the application immediately. We only specify inverters on the current Energy Networks Association type-test register.
How important is the inverter monitoring platform?
Critical. The cloud monitoring platform is how a customer (and us) actually sees that the system is producing what it should. SolarEdge Monitoring is widely regarded as the strongest in commercial PV — module-level data, granular fault diagnostics, mature mobile app. SMA Sunny Portal is solid but module-level visibility requires Tigo TS4 add-ons. Fronius Solar.web is competent. Huawei FusionSolar is feature-rich. Solis SolisCloud and GoodWe SEMS are functional but lighter. We weight monitoring quality heavily in inverter selection for any high-value system where downtime matters.