Best Brands for String Inverter Monitoring in the UK

How we scored them

Monitoring quality is the bit of an inverter quote nobody interrogates, and it’s the bit you’ll touch every week for a decade. So we ranked each platform on seven things: how much granularity you actually get (system, per-string/MPPT, or per-panel); app stability when you open it at 7am with a coffee; whether export and battery flows are clearly drawn; how intelligible the alerts and fault codes are; whether there’s open local access for tinkerers; whether anything sits behind a paywall; and — new for 2026 — whether the brand behind it will still be supporting UK customers in five years’ time. That last criterion did more damage to the leaderboard than any app-store rating.

The 2026 string inverter monitoring leaderboard

*SolarEdge is technically a string inverter plus per-panel optimisers, which is exactly why it’s here — more on that below. User-reported satisfaction from our best monitoring apps guide puts mySolarEdge at 7.5/10, FusionSolar and the all-in-one Sigenergy tied at 7.0, and SolisCloud and FoxESS Cloud both at 6.5; Fronius and SMA weren’t scored there because so few new UK quotes carried them until recently.

Brand-by-brand verdicts

Fronius Solar.web — the data nerd’s champion

Free basic monitoring, a paid premium tier if you want every last decimal, and — the killer feature — an open, local JSON API that Home Assistant integrates with natively. Installer-grade analytics without an installer-grade attitude. If your quote includes a Fronius Primo GEN24, the monitoring question is answered.

SMA Sunny Portal (powered by ennexOS) — the dependable one

Less pretty than Fronius, utterly reliable, and its alert workflows are the reason installers love it. SMA has been migrating Sunny Portal Classic systems across to ennexOS in stages for several years now, working through Sunny Home Manager 2.0 setups country by country — so check which portal your quote assumes before you commit.

Solis Cloud & Sungrow iSolarCloud — the value pair

SolisCloud is simple, steady and better on a desktop than on a phone; exactly what a budget string system needs — our Solis inverter review has the full hardware breakdown if you’re weighing it up. iSolarCloud is the more feature-rich of the two — fault management, smart push alerts, a redesigned “energy cockpit” — though user feedback consistently rates it very good rather than excellent. Either is a fine answer at value pricing.

Fox Cloud, ShinePhone, SEMS — functional, with caveats

Fox ESS’s cloud gives a clear battery-and-grid flow view, but user reviews split hard between “clear and reliable” and connectivity-drop complaints. Growatt’s ShinePhone tracks everything including tariff-based scheduling, yet feels slow and a generation old in the hand. GoodWe’s SEMS is the weakest of the bunch in user feedback — crashes and missing consumption data come up too often. None is a reason to reject a good cheap system; all are a reason to weigh the app before you weigh the price.

The optimiser exception: SolarEdge

SolarEdge runs a string inverter on your wall but hangs a power optimiser — roughly £40 a panel in hardware — behind every panel, so mySolarEdge shows you per-panel production that no plain string platform can match. The trade-offs are a cloud API rate-limited to around a 15-minute refresh (local Modbus TCP is sometimes enableable if you ask at install), and a 12-year inverter warranty against the optimisers’ 25. Our SolarEdge vs Enphase monitoring comparison goes deeper, and the microinverters vs string inverters guide has the lifetime cost maths.

The Huawei question

Let’s be plain, because this catches people out: Huawei withdrew its residential FusionSolar range from the UK in January 2026. Existing owners keep valid warranties and a still-excellent app — FusionSolar’s live flow view and LUNA2000 integration are why it scores 7.0 in our apps guide — and local Modbus TCP access keeps the Home Assistant crowd happy, albeit with a one-connection-at-a-time quirk. But if you’re being quoted a “new” SUN2000 today, something’s wrong. The replacements UK installers actually fit now are SolarEdge’s SE-H series, the Solis S6 hybrid, Fronius Primo GEN24 and Sunsynk hybrids, as we covered in our Huawei SUN2000 review.

What string monitoring can’t see

A string inverter measures what arrives at the unit, nothing more. Panels wired in series share current like old Christmas lights — one shaded or failing panel drags its whole string down, and the app just shows a slightly dull day. That blindness has a price: a single silently underperforming panel can cost 200–600 kWh a year, roughly £150 at current cap rates, with no alarm to tell you — our solar panels underperforming guide covers how to actually catch this. On a clean south-facing roof that risk is small and string-level data is genuinely enough. On a roof with chimneys, dormers or trees, per-panel visibility from optimisers or microinverters earns its premium — our complete monitoring systems guide walks through which architecture suits which roof.

The whole argument in one diagram: granularity is decided on the roof, not in the app store.

Open APIs and Home Assistant

If you run home automation, monitoring brand becomes a hardware decision. Fronius is the gold standard: an open local REST API plus a Solar.web Query API, and a native Home Assistant integration. Huawei exposes Modbus TCP locally (one session at a time, mind). SolarEdge’s cloud API is the slow lane unless your installer enables local Modbus at commissioning. Solis, Sungrow, Growatt, GoodWe and Fox are cloud-led, which is fine for glancing at a phone and frustrating for automating a house. Whichever you pick, third-party tools like Home Assistant’s energy dashboard, Bright and PVOutput can layer on top — our apps guide covers those in full.

Alerts worth having

The day monitoring earns its keep is the day it pings you. The best platforms separate trivial warnings from lockout faults, and speak plainly when the UK’s favourite non-fault — grid overvoltage past 253V under G99 rules — trips the system on a bright weekday. Brand dialects differ wildly (Fronius’s State 102 family, SMA’s “Grid overvoltage”, Growatt’s “PV Isolation Low”), so whichever platform you land on, bookmark our fault codes explainer — it translates the lot.

Export, SEG and checking you’re paid properly

Monitoring is also your receipts folder for the Smart Export Guarantee. Your supplier pays from half-hourly smart-meter export readings, not from your app — but your app is how you spot a mismatch. Log monthly export kWh, compare it against what your supplier credits, and if the gap is wide, query it. With fixed SEG rates spanning roughly 3p to 25p/kWh and time-of-use peaks higher still, tariff choice alone swings over £150 a year on a typical 4kW system; our SEG tariff comparison tracks who pays what right now. For eligibility rules and the official licensed-supplier list, the government’s Smart Export Guarantee overview is the source of truth.

Our quick picks by household