Hoymiles microinverters in the UK: HMS models, G98 and warranty

Hoymiles is worth comparing if you want microinverters under the panels, with each panel tracked and monitored, or a plug-in kit built on Hoymiles units that is on the ENA register. Its HMS range has models for two or four panels, and their outputs, connectors and gateways aren't interchangeable without a design check. The warranty is 12 years, and Hoymiles's European terms let you extend it to 25 years for models without built-in Wi-Fi. Look for the exact model, the DTU gateway and a named person for claims on the quote; "Hoymiles HMS" on its own isn't enough.

Hoymiles at a glance

Two or four panels per unit

A microinverter sits behind the panels and converts each panel's output to mains electricity on the roof. Hoymiles's HMS range comes in several forms:

A four-panel unit means fewer boxes on a large, even roof. With four independent MPPTs (maximum power point trackers), each panel is tracked on its own, which helps when panels see different sun. It doesn't remove shade, and each panel must still suit the input's voltage and current limits. Two-panel units split a small or awkward roof more finely but aren't always cheaper once cabling, accessories and the gateway are added. Compare the predicted kWh and the total price, not the number of boxes.

Hoymiles says models can share one system only if they use the same AC connection and the same way of talking to the DTU, giving the HMS-800-2T and HMS-1600-4T as an example. Keep the codes of every unit, connector and gateway if you might add panels later.

G98: every unit's output adds up

In Great Britain, a system whose inverters together deliver up to 16 A per phase (3.68 kW on a single-phase supply) connects under G98, and the installer tells the network operator within 28 days. Go over it and G99 applies: the network operator has to say yes before the system is switched on. With microinverters, it's the total of all the units that counts, not each one on its own.

Using the rated current at 230 V from Hoymiles's datasheets:

• four HMS-800W-2T units: 4 × 3.48 A = 13.9 A (3.2 kVA), within G98;
• five HMS-800W-2T units: 5 × 3.48 A = 17.4 A (4.0 kVA), so G99;
• two HMS-2000-4T units for eight panels: 2 × 8.70 A = 17.4 A (4.0 kVA), so G99.

Each of these models is listed on its own as compliant on the ENA type-test register; that doesn't make the whole system G98. Check the manufacturer name on the register too: a different company, Suzhou Hypontech, lists models called HMS-800W and HMS-2000W. Northern Ireland uses G98/NI and G99/NI.

What actually comes off the roof

A panel's Wp rating is measured in a lab; a microinverter's VA rating is the most it will send to your wiring. Four 500 Wp panels add up to 2,000 Wp, but an HMS-2000-4T won't deliver 2,000 W all day: weather, angle, heat and losses all cut output. Putting slightly more panel power behind a unit can be a deliberate choice. Ask the installer how much energy would be clipped at midday, because an east–west roof peaks less sharply than a single south face. Our guide to microinverters and string inverters compares the two approaches.

Plug-in kits

Hoymiles's HMS-800W-2T datasheet (Europe edition) describes it as designed for balcony systems, with an optional plug cable fitted with a Schuko (continental) plug. In Great Britain, plug-in solar has been legal since 27 August 2026 only for kits that meet the government's product specification: up to 800 W, no battery, one kit per household for now, and the network operator must be told. The ENA register has a separate plug-in category that lists whole kits, including City Plumbing kits built on Hoymiles HF-800-WB and HMS-800-2WB units (published August and September 2026).

So buy a complete kit that is registered as a plug-in kit, rather than a bare European microinverter. A kit bought without installation carries 20% VAT, and payments for exported power aren't established for plug-in kits. Hoymiles's warranty terms say they apply only to products installed by a qualified professional, so ask the seller in writing how that affects a kit you plug in yourself. Our plug-in solar guide covers the rules and savings.

DTU, S-Miles Cloud and faults

Rooftop HMS units report to a DTU gateway, which sends data to S-Miles Cloud; W models have Wi-Fi built in. The DTU is more than a nice extra: Hoymiles's warranty terms say it is needed for remote fault diagnosis and to start a warranty claim. Make sure the quote names the DTU model and that your internet reaches it.

At handover, set up your own account and check that each panel appears in the right place on the layout. A mix-up makes it hard to find a faulty unit later. A lost connection isn't always a failed microinverter, so ask who receives alerts and how long the installer's monitoring lasts. Our guide to solar panel monitoring explains what to compare through the year.

Warranty and service

Hoymiles publishes warranty terms for the Europe region (updated July 2026), and lists its UK support line with its European support desks. The main points:

• Length: 12 years for all HMS models, including W models and HiFlow. Models without built-in Wi-Fi can be extended to 25 years if you apply through the seller within 36 months of purchase; ask the seller whether there is a charge. Wi-Fi models can't be extended.
• Start: installation, or four months after Hoymiles ships the unit if that is earlier.
• Moving home: the warranty transfers only if the product stays where it was installed.
• What it pays: a replacement unit. It doesn't cover removing the faulty unit and fitting the new one, access equipment for pitched roofs, or travel.
• Claims: go through your installer, who works with the distributor. If no fault is found, Hoymiles can charge an inspection fee of €100 per unit plus shipping.

The terms say they cover products installed to the technical specifications and certifications of the Europe region, without listing countries. Ask your installer to confirm in writing that your UK system is covered.

Because a microinverter sits under the panels, a replacement often means scaffolding or other roof access, which Hoymiles's warranty doesn't pay for. Ask whether the installer's workmanship guarantee pays for that visit, and for how long. If a unit fails early or was badly fitted, the Consumer Rights Act 2015 gives you a claim against the business that sold it to you, and a RECC or HIES member offers a dispute route that MCS certification alone doesn't guarantee.

Before you sign

Get in writing (our guide to comparing solar quotes has the full checklist):

1. the exact HMS code of every unit and its datasheet;
2. which panels go on which input, with voltage and current checked;
3. the combined AC output of all units, and whether that means G98 notice or a G99 application;
4. the predicted yield and any expected clipping;
5. the DTU model, your S-Miles Cloud login and a check at handover;
6. the warranty length, any extension, and who pays for roof access.

Grid-tied microinverters switch off in a power cut, so backup needs a separate, designed system. Panels supplied and installed in your home have 0% VAT until 31 March 2027, then 5% unless the relief is extended, and for a rooftop system in Great Britain, electricity suppliers pay for exports through their own Smart Export Guarantee tariffs once they see an MCS certificate (or equivalent). Our calculator estimates a system size for your roof.

Frequently asked questions

Does an HMS-2000-4T always produce 2,000 W?

No. 2,000 VA is the most it will output. What you get depends on the panels, the sun, the temperature and the design.

Can I add another Hoymiles microinverter later?

Sometimes. Hoymiles allows mixed models only with the same AC connection and the same DTU communication, and the new total output may move you from G98 to G99.

Do Hoymiles microinverters work in a power cut?

No. Grid-tied microinverters shut down when the grid fails. Backup needs a system designed to isolate and power chosen circuits.

Can I use a Hoymiles microinverter as a plug-in kit?

In Great Britain, use a complete kit listed as plug-in solar on the ENA register, up to 800 W and one per household for now. A bare microinverter with a continental plug isn't the legal route. Northern Ireland needs its own rule change first.