SolarMax F07 — Overload Time-Out

What it means: The inverter has been running above 110% of its rating for longer than it will tolerate and has timed out, shutting the output down. SolarMax's troubleshooting table puts it plainly — "overload error, the inverter is overload 110% and time is up; reduce the connected load by switching off some equipment." The same condition while the machine is still coping shows first as warning 07 with one beep every half second. This is not a fault in the inverter; it is the inverter telling you it is being asked for more than it has. Verified against SolarMax's SM-ORION-DUAL-4KW manual (Axpert-class SolarMax hybrids — ORRA, SOLON, ORION, FALCON).

Why does SolarMax show F07?

• Total connected load simply above the inverter's rating — an air conditioner, a pump, an iron and a geyser element on the same backup circuit
• Motor start-up surge from a compressor, water pump or deep freezer arriving on top of an already high base load
• Load sitting near rated power while the inverter is hot, because a hot inverter derates
• A faulty appliance drawing far more than its nameplate
• Non-essential circuits wired onto the backup side when the system was installed
• Low utility voltage. SolarMax's own derating curve shows output power being derated once the AC input drops to 170 V, so on a sagging feeder the same load becomes an overload

The Pakistan factor

F07 is mostly a sizing and sales problem rather than a technical one. Systems get sold on the nameplate — "10 kW runs your whole house" — and the whole house in a Pakistani summer means one or two air conditioners, a borewell or booster pump, and a deep freezer, all of which start under load. The second driver is the feeder. SolarMax's own curve derates output once AC input falls to 170 V, and evening voltages on end-of-line rural and semi-urban feeders in Punjab and interior Sindh routinely sit in that region, so the same load that ran fine at midday overloads at 8 p.m. The third is heat. An inverter already close to F02 has less headroom, which is why F07 and F02 tend to show up in the same week in June.

How to fix it (safe to try yourself)

1. Switch off the heavy items before you restart — air conditioner, water pump, iron, geyser, washing-machine heater, welding set. This is the manufacturer's own remedy, word for word.
2. Restart the inverter and bring the loads back one at a time, biggest last, watching the load bar and the load-watt figure on the LCD as you go.
3. Add up what you genuinely run at the same time and compare it against your model's rating. If your worst case is above the rating, no setting will fix it. Either move loads off the backup side or fit a larger inverter.
4. Watch for motor starts specifically. A pump or compressor can draw several times its running current for a second or two. If F07 only fires the instant the pump kicks in, that is your answer — stagger those loads, or have an installer fit a soft starter.
5. Leave program 06, auto restart when overload occurs, on its factory setting of Restart disable unless your installer has a specific reason to change it. Enabling it hides a real capacity problem behind repeated restarts into the same overload.
6. Check the grid voltage on the display at the times F07 happens. If it is sitting near or below 170 V the inverter is derating and the fault is partly the feeder's. Log it and report persistent low voltage to your DISCO in writing.
7. If F07 fires with a small, known load such as a few fans and lights, stop treating it as an overload. Have an installer measure the actual current, because at that point either an appliance is faulty or the inverter is misreading.
8. Do not remove, bypass or uprate the output breaker to keep the load connected. The overload protection is what stops the wiring behind the wall from becoming the fuse.