Understanding Inverter Error 04: What It Is and How to Fix It – with Sona Solar Zimbabwe

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Everything You Need to Know About Inverter Error 4 – Causes, Solutions, and Prevention with Sona Solar Zimbabwe

Introduction: Why Error 4 Matters for Every Solar User

Solar energy systems are designed to provide clean, uninterrupted power - but like all technology, they require proper maintenance and system understanding. One of the most frequent challenges faced by solar users in Zimbabwe is Error 4, a fault code that appears on many inverters such as Axpert, Must, Growatt, Mecer, Deye, and Sunsynk.

As Sona Solar Zimbabwe, our role is not just to install systems, but to educate our customers, provide sustainable power solutions, and respond professionally when issues like Error 4 arise.

What Is Inverter Error 4 – A Technical Perspective

Error 4 typically signifies a Battery Under Voltage error. This is a protective shutdown mechanism built into your inverter. When the voltage of your battery bank drops below the minimum safe level, the inverter halts operation to prevent deep battery damage.

Here’s what it looks like in numbers:

• 12V battery system - Error 4 usually triggers below 10.5V
• 24V battery system - Triggers below 21V
• 48V battery system - Triggers below 42V

This error is not a failure—it’s a warning and safety feature. The good news? It's fixable. The better news? It’s preventable with the right knowledge and system care.

 

What Causes Error 4? Let’s Get into the Details

1. Deep Battery Discharge

If you’re using more power than your batteries can supply, and the batteries aren’t being recharged sufficiently by solar or grid, the voltage eventually drops too low. This is common during long load shedding hours or cloudy days.

2. Battery Aging and Degradation

All batteries have a lifespan. Lead-acid and GEL batteries degrade faster than lithium. Over time, they lose their ability to hold charge efficiently, and the voltage dips quickly under load.

Understanding Inverter Error 04: What It Is and How to Fix It – With Sona Solar Zimbabwe

Tip from Sona Solar: If your batteries are more than 3 - 5 years old and you’re getting Error 4 frequently, it’s time for a health check, or an upgrade to lithium. 

3. Poor System Configuration

Using lithium batteries but not updating your inverter settings (like charge cut-off, bulk/float voltages, BMS communication) can trigger under-voltage errors, because the system doesn’t know how to manage your batteries correctly.

4. High Load Devices

Appliances like boreholes, geysers, irons, fridges, or microwaves cause sudden power surges. If turned on while batteries are low, they cause the voltage to dip and trigger Error 4.

5. Loose or Rusty Battery Connections

Corrosion or poor-quality wiring increases resistance in the battery circuit. This creates voltage drop, which may falsely signal low battery voltage, even if the batteries are actually fine.

Sona Solar’s Step-by-Step Solution Approach

At Sona Solar Zimbabwe, we don’t guess - we diagnose and resolve. Here's how we typically handle Error 4:

Step 1: Recharge and Reset

We first ensure your battery gets a full charge, either via solar or grid, and then reset the inverter if needed. This sometimes resolves the issue quickly.

Step 2: Battery Performance Testing

Using digital battery testers, we check:

• Voltage under load
• Internal resistance
• Remaining battery capacity
• Number of charge/discharge cycles (especially for lithium)

Step 3: Configuration and Firmware

We verify your inverter’s software version, battery type settings, and charge voltage parameters. For lithium users, we ensure communication between the Battery Management System (BMS) and the inverter is working perfectly. 

Step 4: Upgrade or Replace Components

If necessary, we recommend and supply new, high-efficiency batteries like:

• Dyness Lithium (long-life, low-maintenance)
• PylonTech (BMS-integrated and scalable)
• Felicity Solar (affordable lithium)

We also replace worn-out fuses, cables, or terminals to improve system safety and voltage flow.

Step 5: Educate the Client

We believe in empowering our clients. We show you how to:

• Monitor your battery voltage in real-time
• Avoid overloading your inverter

Use your appliances smartly during peak/off-peak hours 

How to Prevent Error 4 from Returning

• Invest in Lithium Batteries: They discharge deeper without damage and recover faster.
• Use Solar Wisely: Schedule high-consumption appliances when sunlight is strong.
• Install a Monitoring System: Apps or LCD displays help you track battery health.
• Get Regular System Checks: Every 6–12 months, let our team run maintenance diagnostics.

Why Sona Solar Zimbabwe Is Your Best Choice

Choosing Sona Solar means more than just buying solar equipment. It means partnering with a team of energy experts who care about the long-term success of your system.

We provide:

• Professionally sized systems based on your actual energy usage
• High-quality inverters (Must, Growatt, Sunsynk, Deye, Mecer)
• Genuine lithium batteries with warranty
• Full technical support, even if we didn’t install your system

May Promotion – Error 4? No Problem!

This May, enjoy our Winter Readiness Campaign:

• Free fault diagnosis if you’re experiencing Error 4
• Up to 15% off lithium battery upgrades
• Custom-built solar packages to suit home, business, or farm needs

We’ll help you eliminate battery faults for good, and keep you powered through winter. 

Contact Sona Solar Zimbabwe Today

For assistance, repairs, upgrades, or a system health check:

Visit Us: 7 Frank Johnson Avenue Eastlea, Harare
Call or WhatsApp: 078 119 0001
Website: sonasolar.co.zw

Final Thought from the Experts

Error 4 is not the end, it’s a signal that your system needs attention. With the right diagnosis, technical expertise, and component quality, it’s easy to fix and even easier to prevent.

At Sona Solar Zimbabwe, we don’t just sell solar, we provide peace of mind, energy independence, and expert guidance every step of the way.