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.
Growatt Inverter Error 04 — Low Battery Voltage, Causes and Safe Steps
Error 04 on a Growatt SPF off-grid inverter means the battery voltage has fallen too low for the inverter to keep running. The inverter stops its output to protect both itself and the battery. It is most common after heavy overnight use or a run of cloudy days — once the battery recharges, the inverter resumes normally.
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?
Is your system producing power right now?
What this code means
This code belongs to Growatt’s SPF off-grid inverter range (models like the SPF 3500/5000ES and SPF TL HVM series), which run your home from batteries charged by solar. Growatt’s manual lists fault code 04 plainly: ‘Battery voltage is too low.’ When the battery voltage sags below the inverter’s cut-off point, the unit shuts down its output rather than draining the battery into damage — deep-discharging batteries, especially lead-acid types, shortens their life dramatically.
You’ll typically meet 04 in the morning after a night of heavy loads, or during a stretch of gloomy weather when solar charging can’t keep up. The inverter usually announces it with a buzzer beeping once per second and a flashing red LED. For lithium batteries, the manual also points you to the state-of-charge reading on the LCD — a low SOC confirms the battery is simply empty rather than faulty.
Sometimes 04 is a symptom rather than the story: aging batteries that have lost capacity will hit the cut-off much earlier than they used to, and a lithium battery whose BMS (battery management system) has disconnected itself can read as very low voltage. If 04 appears daily despite good sunshine, the battery bank — not the inverter — is the prime suspect.
Recovery is straightforward: reduce the load and let the battery recharge from solar (or from utility/generator if your system is set up for it). The inverter will come back on its own once voltage recovers. Growatt’s documented checks are to measure the battery voltage at the DC input, check the SOC on the LCD for lithium batteries, and recharge the battery.
What is this downtime costing you?
Rough estimate while your system isn't producing. Adjust the numbers to match your setup.
≈ – 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
- Overnight loads drained the battery below the cut-off voltage.
- Several cloudy days with too little solar charging.
- Battery bank undersized for the household loads.
- Aging batteries with reduced capacity reaching cut-off earlier than before.
- Lithium BMS disconnected the battery (protection trip), reading as very low voltage.
- Battery breaker/isolator off, or a loose battery cable (visual check only).
Safe steps to try
Work top to bottom, ticking off each step as you complete it. 0 of 5 done.
Is your inverter still under warranty?
Before paying for a repair, check — your installer may fix this free.
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 battery voltage doesn’t rise while charging, if batteries are swollen, leaking, unusually hot, or smelling, if the BMS shows errors, or if 04 has become a daily event. Never open the battery bank or the inverter, and never attempt to jump-start or rewire batteries yourself.
Frequently asked questions
Is error 04 dangerous?
Not by itself — it’s a protection response. The inverter shuts down to prevent the battery from being damaged by over-discharge. The underlying cause (a deeply drained battery bank) deserves attention, but the code itself is the system protecting itself.
How long does it take to clear?
As long as the battery needs to recharge past the cut-off point — anywhere from an hour of strong sun to most of a day, depending on how empty the bank is and how much solar is available. Reduce loads to speed it up.
Why does 04 happen every night now when it didn’t before?
That’s the classic sign of aging batteries losing capacity, or of loads creeping up over time. A bank that once sailed through the night now hits the cut-off before dawn. Ask your installer to test the batteries’ health.
Can I still use power while 04 is showing?
If your system has a utility or generator bypass, those loads may still work — but the inverter won’t produce from battery until it recharges. Don’t try to force it; let the battery recover.
Does 04 mean my batteries are dead?
Not necessarily. One occurrence after heavy use or bad weather is normal. It’s only when 04 becomes routine — daily, despite decent charging — that the batteries are likely worn out and need professional testing.
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 — Growatt SPF series User Manual — Fault Reference Code: ‘04 Battery voltage is too low’; Troubleshooting: ‘Warning code 04 — The battery voltage/SOC is too low: 1. Measure battery voltage in DC input. 2. Check battery SOC in LCD when use Li battery. 3. Recharge the battery.’ (official Growatt manuals, africa.growatt.com and hg.growatt.com; content confirmed from the official documents as indexed — direct PDF fetch timed out).