Warning What does this mean?

Your system is down or running degraded, but this is not an immediate safety danger. Work through the safe steps below.

GoodWe Inverter Errors 18 and 19 — Overheating Causes and Cures

Errors 18 ('Temperature Too High') and 19 ('Over Temperature') are GoodWe's thermal protection codes: the inverter's case or internal temperature has risen past the safe operating limit. The unit protects itself by reducing output (derating) or shutting down, and it restarts automatically once it cools. Almost every case comes down to the installation environment — poor ventilation, direct sun, or blocked heatsink fins. Clear the airflow, add shade with proper clearance, and let it cool. If the errors keep returning on mild days with good ventilation, the internal fan may be failing and you need service.

What should I do first?

Two quick questions — we'll point you to the right starting point.

Is this code still showing on your inverter's display?

What this code means

Think of Errors 18 and 19 as the inverter's sweat response. GoodWe documents them side by side in its error tables: Error 18 as "Temperature Too High" and Error 19 as "Over Temperature — overtemperature on the case." Both mean the same underlying thing: a temperature sensor inside the unit has crossed its protection threshold, and the control board has decided that making full power right now would cook the electronics. The response is graduated — first the inverter quietly trims its output so it generates less internal heat (you might notice lower-than-expected midday production on hot days), and only if temperatures keep climbing does it shut down entirely.

GoodWe's official troubleshooting for overtemperature is refreshingly practical and homeowner-friendly: the internal temperature is higher than the specified normal value, so reduce the ambient temperature and move the inverter to a cooler place — and if the problem persists, contact the local service office. The pattern of when the errors strike tells you most of what you need to know: blazing afternoons only means environment; mild mornings too means something is wrong inside the box.

What is this downtime costing you?

Rough estimate while your system isn't producing. Adjust the numbers to match your setup.

System size (kW) Peak sun hours / day Electricity rate ($/kWh)

–per day

–per week

–per 30 days

≈ – kWh of lost production per day.

Estimate only — assumes ~80% real-world output vs. nameplate. Actual losses depend on weather, shading, panel direction, and your tariff.

Common causes

Poor ventilation at the installation location — the unit tucked into a dead-air corner, boxed in by stored items, or installed without the clearances the manual requires.
Direct sunlight on the casing, worst on west- or north-facing walls (southern hemisphere) catching full afternoon sun, which can push case temperature far above air temperature.
Blocked heatsink fins or air paths: dust buildup, spider webs, leaves, or vegetation grown up against the unit since installation.
Extreme ambient heat during heatwaves, especially in unventilated sheds or garages.
A failing internal cooling fan that can no longer move enough air — often the real story when the errors persist despite good ventilation and mild weather.

Safe steps to try

Work top to bottom, ticking off each step as you complete it. 0 of 5 done.

Clear at least 300 mm of open space around the heatsink fins and the whole unit. Move bins, garden tools, and anything stored against it.
Clean the heatsink fins and air inlets from the outside — brush off dust, webs, and leaves. Work from outside only; never open the casing and never use water.
If the unit bakes in afternoon sun, fit a shade hood or awning above it, mounted with generous clearance so air keeps flowing underneath. Do not enclose the inverter.
Watch the pattern: errors only on 35°C+ afternoons point to environment; errors on mild days point to a possible fan fault — listen for whether the internal fan is running during hot operation.
Let the inverter manage itself. It derates and restarts automatically; there is no need to switch it off manually during a heatwave, and frequent manual power-cycling does not help.

Is your inverter still under warranty?

Before paying for a repair, check — your installer may fix this free.

Brand Year installed

Based on typical standard warranty terms — always confirm with your warranty card or installer paperwork, as terms vary by model, region, and purchase date.

When to call an electrician

Call your installer or GoodWe's local service office if the temperature errors keep appearing after you have fixed ventilation and shade, or if they occur in mild weather — that pattern suggests the internal fan is failing or a temperature sensor is faulty, and both are service jobs. GoodWe's manual gives this exact escalation: if the problem still exists after cooling measures, contact the local service office. Treat it as urgent if you smell hot electronics or see any discoloration of the casing: switch the system off via the external AC and DC switches and get a professional promptly. Never open the unit to inspect or replace the internal fan yourself.

Frequently asked questions

What is the difference between Error 18 and Error 19?

They are two thresholds of the same thermal protection. Error 18 ('Temperature Too High') is the earlier warning stage; Error 19 ('Over Temperature — overtemperature on the case') is the firmer trip. Both are solved the same way: airflow and cooling.

Will the inverter restart by itself?

Yes. Thermal protection is self-recovering: the unit derates first, shuts down if necessary, and resumes normal operation automatically once temperatures fall back into range.

My production dips every hot afternoon but there is no error. Is that related?

Very likely. Derating happens before any error code appears — the inverter quietly trims output to stay within temperature limits. Better ventilation and shade will recover some of that lost afternoon production.

Can I point a fan at the inverter or install extra cooling?

Improving external airflow is fine and helps — a shade hood with good clearance is the classic fix. What you must not do is open the casing to interfere with the internal fan or heatsinks; that is service work and a warranty risk.

Does repeated overheating damage the inverter?

Occasional hot-day derating is within design limits. Chronic overheating shortens the life of capacitors and power electronics, so a pattern of daily temperature errors across a whole summer deserves a proper fix — shade, relocation, or a fan replacement by your installer.

Need a professional?

This fault may need professional diagnosis. Contact a qualified solar electrician in your area.

Sources: meaning and troubleshooting verified against the manufacturer's documentation — GoodWe MT G2 Series Grid-Tied PV Inverter User Manual, Section 5.9 'Error Message Description' — Error 19 'Over Temperature: Overtemperature on the case'; troubleshooting: 'The internal temperature is higher than normal value specified. Reduce ambient temperature. Move the inverter to a cool place. If the problem still exists, contact local service office for help.' Error 18 'Temperature Too High' per GoodWe official error-code reference (goodwe.com).