Solar optimiser questions, answered.
Straight answers about solar optimisers on UK roofs: what they do, how the Archai iOPT 800W and GT gateway work, which inverters they're certified with, and how to install them safely. Each answer links to the page or datasheet behind it.
The basics.
What is a solar optimiser?
A solar optimiser is a small DC-to-DC converter fitted behind each solar panel. It tracks that panel's maximum power point (MPPT) on its own, so a shaded, dirty or differently angled panel no longer drags down the rest of the string. Archai's optimiser, the iOPT 800W, also reports live per-panel data and supports rapid shutdown.
Do solar optimisers help with shading on UK roofs?
Yes, that is their main job. On a plain string, one shaded panel can pull down the output of every panel on the same string. With an optimiser on each panel, every module runs at its own best point. On a UK residential install in the north-west of England, Archai optimisers on shaded strings gave a 10–15% uplift over the baseline.
Optimisers or microinverters: which is better for a UK home?
Both give panel-level MPPT and monitoring. Optimisers keep a central string inverter, so installers can carry on fitting the inverter brands they already use, such as Solis or Fox ESS. Microinverters convert to AC on the roof instead. Which is better depends on the job; our guide compares the two in detail.
What is MPPT and why does it matter?
MPPT (maximum power point tracking) continually adjusts a panel's voltage and current to the point where it produces the most power. That point moves with light, temperature and shade. Doing it per panel, as the Archai iOPT 800W does at up to 99.7% peak MPPT efficiency, recovers energy a single string-level tracker would lose.
Archai products.
Who makes Archai optimisers?
Archai Power (Archai Powertech Ltd, registered in England & Wales, company no. 15067216) is a UK solar technology company. Its system is the Archai iOPT 800W optimiser, the Archai GT data gateway and the SolarSync monitoring platform, sold through UK installers and distributors and supported by a UK team.
What are the key specifications of the Archai iOPT 800W optimiser?
Max input power 800 W; max input voltage 70 V; MPPT range 12–60 V; max continuous current 21 A; peak MPPT efficiency at least 99.7%; max system voltage 1500 V; output 0 W during shutdown; IP68; operating temperature −40 °C to +65 °C; genuine Stäubli MC4 connectors; 116 × 31.5 × 123 mm and 0.865 kg.
How many optimisers can one Archai gateway handle?
One Archai GT data gateway handles up to 30 iOPT 800W optimisers. It sits in series between the string and the inverter, reads optimiser data over the DC cable (PLC) and sends it to SolarSync over 2.4 GHz Wi-Fi or RS485.
Does Archai monitoring need Wi-Fi on the roof?
No. Optimiser data travels over the existing DC cable using power line communication (PLC), so there is no wireless link on the roof to drop out. Only the gateway, installed near the inverter, connects upstream by Wi-Fi or RS485.
What connectors do Archai optimisers use?
Genuine Stäubli MC4 connectors (PV-KBT4 / PV-KST4), the connector family premium panel makers fit. They are rated 1100 V DC (IEC) / 1500 V DC (UL) and 39 A on 4 mm² cable, with contact resistance below 0.25 mΩ. Mating MC4s from different makers voids their certification and is a leading cause of DC arc faults.
What warranty do Archai optimisers have?
Archai optimisers come with a 25-year replacement warranty, and warranty claims are handled by the team in the UK.
Compatibility and approvals.
Which inverters are Archai optimisers compatible with?
Archai is certified with Solis inverters (official compatibility certificate issued September 2025) and Fox ESS single-phase inverters, with confirmed models H1-6.0-E-G2 and KH8. Fox ESS three-phase is still in testing. For any other inverter, ask the team before specifying.
Do I need to change inverter brand to use Archai optimisers?
No. Because Archai is certified with Solis and Fox ESS, installers can add panel-level optimisation while keeping the inverters they already fit.
Are Archai optimisers approved for ECO4?
Yes. The Archai system is approved by Ofgem under the ECO4 Innovation Measure as IM045 (solar PV, substantial innovation measure), approved on 9 January 2026. ECO4 itself runs until 31 December 2026, and approved Innovation Measure uplifts are honoured until then.
Safety and installation.
Do Archai optimisers provide rapid shutdown?
Yes. Pressing the RSD button on the GT gateway, or removing its AC supply, takes every optimiser to a safe output of about 1 V per panel within 30 seconds. That lowers the DC voltage on the roof for maintenance and emergency access.
How do you install Archai optimisers?
Fit one optimiser behind each panel, MC4 in and out. Wire the GT gateway in series: last OUT+ to the inverter PV+, first OUT− through the GT ring to PV−, and give the gateway a 90–264 V AC supply. Run the 10-minute self-test from the gateway button, then map each optimiser in SolarSync.
How should I design a string with optimisers?
Check each panel's voltage and current against the optimiser's input limits (12–60 V MPPT, 70 V max, 21 A continuous), count no more than 30 optimisers per gateway, and check the string against the inverter's MPPT window. Our worked example walks through a real string.
Where can installers buy Archai optimisers and get training?
Archai sells through UK distributors and stockists, and runs a free Certified Installer programme with about 90 minutes of online training, a listing on the find-an-installer map and a priority technical line.
How does Archai compare with Tigo?
Both offer panel-level optimisation, monitoring and rapid shutdown. Our side-by-side comparison sets the published specifications of the Archai iOPT 800W against the Tigo TS4-A-O, with sources for every figure.
Ask the UK team.
Email hello@archaipower.com or use the contact form. We reply within one working day.