A red light on an inverter almost never means the inverter is broken. It usually means the inverter has detected a condition outside its safe operating window — in the array, in the grid, or in the battery — and has disconnected on purpose.
Your display shows a numeric fault code. Read the code in the manual for your unit rather than trusting a code list on a web page, including this one: codes differ between models and firmware versions, and acting on the wrong one at a live board is how people get hurt. What follows is the category the code will fall into.
DC over-voltage — the array is producing more than the input accepts
String voltage rises as the cells get colder. A bright, freezing morning is when this appears, which is why it is nearly always a winter fault on a system that ran fine all summer.
Clears itself? Usually, as the day warms. Recurring? The string is likely too long for the inverter's input window and wants restringing. That is a design fault, not a maintenance one, and it should be fixed rather than tolerated.
Grid out of range — voltage or frequency outside limits
The inverter continuously measures the supply and disconnects if it drifts outside statutory limits. It is protecting your house from the grid and protecting anyone working on the network from your inverter.
Clears itself? Yes, after the supply has been stable for a settling period, typically around a minute. Recurring? Persistent high voltage at the origin is a network operator matter and they will investigate it if you report it. Log the times before you call — the pattern is the evidence.
Battery communication lost — the BMS link has dropped
The inverter and the battery talk over a cable, usually RJ45. If that link drops, the inverter stops charging rather than guess at a safe current.
Clears itself? No. First check: the cable at both ends. Push each connector until it clicks. This is the most common single fault in the whole system and the least serious.
Over-temperature — the unit is derating or has stopped
Inverters are specified for an ambient range and shed output above it. An inverter in direct afternoon sun on a south wall, or boxed into a cupboard, will meet that limit every summer.
Clears itself? Yes, on cooling. Recurring? It wants shade or airflow, and both are cheaper than the capacity you are losing each summer.
Before you call
Have three things ready and most faults are answered without a visit:
- A photograph of the display showing the code.
- What the weather and time of day were when it appeared.
- Whether it has happened before, and how often.
Send those through the portal or by email. If the board is showing signs of heat, or you can smell burning, isolate the supply if it is safe to do so from outside the enclosure and call us before doing anything else.