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.

Solis Inverter CAN Fail Alarm — Restoring Lost Battery Communication

“CAN Fail” on your Solis hybrid inverter means the CAN-bus communication link between the inverter and the battery has gone silent. The battery’s management system (BMS) normally streams voltage, current, temperature, and charge limits to the inverter over this cable — without that live data the inverter refuses to charge or discharge the battery, because operating a lithium battery blind is unsafe. The cause is usually mundane: the battery is switched off, the CAN cable has worked loose, the wrong cable type is fitted, or the wrong battery model is selected in the inverter’s menu.

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

CAN (Controller Area Network) is the same rugged communication standard cars use to let dozens of modules talk reliably in an electrically noisy environment. In your solar setup it carries a continuous conversation between two partners: the battery’s BMS, which knows the cells’ state of charge, temperature, and safe operating limits, and the inverter, which needs that information to decide how hard to charge or discharge.

When the manual says “CAN failure is a failure of communication between inverter and battery,” it means that conversation has stopped — the inverter is shouting into a dead line. Its response is conservative and correct: battery operation is suspended. Your panels will typically keep feeding the house and the grid, but anything involving the battery — charging from solar, discharging in the evening, backup power — stops until the link is restored.

Don’t confuse CAN Fail with BatName-FAIL: the latter means the link works but the wrong battery brand is selected, while CAN Fail means no link at all — a physical or power problem.

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

The battery is switched off, in standby, or its breaker is open — no power, no BMS, no communication; the official service FAQ names this first.
The CAN cable is unplugged, loose, or not seated in the CAN ports at the inverter and battery ends.
The wrong cable type is fitted — some batteries require a special communication cable supplied by the battery manufacturer, and a standard network cable won’t establish the link.
A damaged CAN cable — crushed, chewed, UV-degraded, or with a broken locking tab that lets it creep out of the socket.
The battery model selected in the inverter menu doesn’t match the actual battery — the handshake can fail if the inverter is listening with the wrong protocol.
The battery’s BMS is itself in alarm or protection and has stopped transmitting.

Safe steps to try

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

Check that the battery is actually powered on — look for its status lights or display, and make sure its breaker or power switch is on. (A battery deliberately switched off will raise CAN Fail; that’s expected, not a fault.)
Visually confirm the CAN cable is plugged into the CAN port at both the inverter and the battery — look, don’t rewire; if a plug has clearly walked out of its socket you may push it firmly home until it clicks.
Check the inverter menu under Battery Setting → Battery Model and confirm the selected model matches your battery’s nameplate exactly.
If you recently added or replaced the battery, check with your installer whether that battery needs its manufacturer’s special CAN cable — this is a documented gotcha in the Solis manual.
Restart the system once in the proper order (battery off, inverter off, wait a few minutes, battery on, then inverter on) and see whether the alarm clears.

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 if the alarm survives a proper restart with the correct battery model selected, if the CAN cable is visibly damaged, or if the battery itself shows an alarm or refuses to power up. Sourcing the correct manufacturer-specific CAN cable, testing cable continuity, and diagnosing a silent BMS are all installer jobs — and if the battery’s own management system is in protection, the battery manufacturer may need to be involved too. Solis’s service guidance is blunt on this one: check the cable is correctly connected and the battery is powered on; beyond that, it’s a service call. As always, never open the inverter casing — communication ports are on the outside for a reason.

Frequently asked questions

Will my solar panels still work while CAN Fail is showing?

Usually yes — PV generation and grid feed-in don’t need the battery link. What stops is everything battery-related: no charging, no discharging, no backup. You’re effectively running as a batteryless system until the link returns.

What’s the difference between CAN Fail and BatName-FAIL?

CAN Fail means no communication at all between inverter and battery — a dead link. BatName-FAIL means they’re talking but you selected the wrong battery brand in the settings. Fix the first with cable and power checks; fix the second in the Battery Model menu.

Can I just use any network cable for the CAN link?

No. Use the cable specified for your battery — the Solis manual explicitly warns that some batteries require a special cable from the battery manufacturer. The wrong cable is a known cause of exactly this alarm.

Is CAN Fail dangerous?

No. It’s the inverter refusing to operate the battery without supervision data, which is the safe behaviour. The risk would be in the opposite design — an inverter that charged a battery it couldn’t monitor.

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 — Solis S6-EA3P(5-10)KAA-NV-ND-H User Manual (solisinverters.com), §7 Troubleshooting — “CAN Fail: Can failure is a failure of communication between inverter and battery. Check cable conditions. Check to ensure you have it plugged in on the CAN port of the battery and inverter. Check that you are using the right cable. Some batteries require a special cable from the battery manufacturer.”; Solis official service FAQ — “‘CAN Fail’ indicates the CAN communication between inverter and battery is lost. Please double check if your CAN cable is correctly connected and if your battery is powered on.”