Fronius inverter status code: what it means and what to do

Safety first

Don't open the inverter, don't touch cables or plugs and don't turn any switch on the equipment. If you smell burning, see smoke or find the inverter very hot, step away and ask for help; if there is fire, call 112.

Where to find the code

• On the inverter display or in Solar.web, in the event list, which shows the number and the status name. On GEN24 models, codes are read in the inverter's web interface and in Solar.web.
• On the side label, the full model. You need the model to read the right manual.
• Photograph the display and the lights without touching.

Where the maker's lists are

The codes below are summed up, in our own words, from the diagnostics chapters of the Fronius operating instructions, read on 2026-10-22: A, Primo 3.0-1 to 8.2-1; B, Symo and Eco; C, Primo GEN24; D, Symo GEN24. The numbers and names are the manufacturer's.

Manuals A and B group the codes by class: grid, short interruptions, faults that usually need a trained technician, and warnings where feed-in normally continues. Names differ a little from one manual to another, so the model matters. Each code below says which manuals list it.

Grid, sun and temperature: what you can check

These codes point to the electricity grid, to daylight or to where the inverter is. As a rule, the inverter feeds in again by itself when the cause passes. If they repeat, ask for help.

• 102, AC voltage too high, and 103, AC voltage too low: grid voltage went outside the set range and the inverter disconnects and waits. It comes back by itself when the grid normalises; if it is frequent, it is a matter for the installer (A, B).
• 107, No AC grid: the inverter does not detect the grid. You can check whether there is a power cut at home or in the area. If the solar breaker is off, don't simply switch it back on: ask for help (A, B).
• 108, Stand-alone operation detected: the inverter thinks the grid was disconnected (islanding protection). It returns when the grid comes back; if it repeats, ask for help (A, B).
• 306, PV output too low, and 307, PV voltage too low (names differ slightly between Primo and Symo): not enough panel power or voltage to feed in. This is normal at dawn and dusk. It is only worth asking for help if it shows in good sun (A, B).
• 509, No energy fed into the grid in the past 24 hours: nothing was fed in for a whole day. It may be snow, shade or another fault. Look from the ground for snow or shade on the panels, without going up on the roof, and look for other codes (A, B).
• 517, Power derating caused by too high a temperature: the inverter reduces output because it is hot. You can check whether anything covers the inverter or whether it is in direct sun, without touching it. If it repeats, ask for help (A, B).

Codes that are installer or technician work

For these, the cause may be in the panels, the cables, the insulation or inside the equipment. They are not for the owner: note the code, take a photo and ask for help.

• 112, RCMU error: residual-current monitoring tripped. The inverter tries again; if it repeats, there may be an insulation or wiring problem (A, B).
• 447, Insulation fault: low insulation resistance between the panels and earth. The DC side can carry dangerous voltage in daylight. Don't touch; the check is installer work (A, B).
• 448, Neutral conductor not connected: the neutral conductor is missing at the AC connection. It is work for an electrician or installer (A, B).
• 457, grid relay sticking (Primo) or grid voltage relay fault (Symo): the grid relay does not switch properly and the inverter stops feeding in. Ask a trained technician (A, B).
• 1030, WSD Open: the wired shutdown chain was interrupted, for example because a surge protection device tripped. On GEN24 models it is a repair for a specialist (C, D).
• 1173, ArcContinuousFault: an arc was detected and the 24-hour limit of automatic reconnections was reached. The whole panel system has to be checked for damage, and damaged parts are repaired by specialists (C).

What to send when you ask for help

• The full model, from the label.
• The number and name of the code, as shown.
• A photo of the display and the lights.
• When it started, whether it repeats and whether there was a power cut, snow or building work at home.

We reply within 48 h, assess the case remotely and, if needed, with a visit, and send a written quote with the price stated before you go ahead. See also the Fronius page and equipment repair.

About this information

These are general points and don't replace the manual for your model, which prevails. The manuals give short remedies, often 'clears itself' or 'contact your installer'; electrical checks are installer work. The manual pages carry no issue date. Fronius is a trademark of its owner. Sol de Volta is a company independent of the manufacturer and does not speak for the brand.