Inverter Fault: Symptoms, Costs, and What to Do Next

The inverter is the heart of your photovoltaic (PV) system. If it fails, electricity production comes to a halt, and every sunny day means lost savings. This guide explains how to identify a faulty inverter, what common error codes indicate, which checks you can safely perform yourself, and what you can expect to pay for a repair or replacement.

Is the Inverter Really Faulty? The Most Common Symptoms

Before calling a qualified installer, it’s worth confirming that the inverter is actually the source of the problem. Typical signs include:

• Complete loss of power generation: the system is no longer feeding electricity into the grid.
• Significantly reduced output despite sunny conditions, often developing gradually over several weeks.
• Red or orange warning lights and error codes are displayed on the inverter or in the monitoring app.
• Unusual noises such as humming, clicking, or buzzing.
• Frequent restarts or a permanently blank display.

Understanding Error Codes

Modern inverters display an error code when a fault occurs. Make a note of the code before restarting the unit, as it will help speed up the diagnosis.

Manufacturer	Typical Error Message	Possible Cause
SMA	Riso / Insulation Fault	Moisture or a ground fault on the DC side
Fronius	State 102 / 103, AC Voltage	Grid voltage outside the permitted range
Kostal	Insulation Fault	Insulation issue with the PV modules or cabling
Huawei	Voltage / Input Error	Grid or DC voltage disturbance
SolarEdge	Arc Fault / Error 18xx	Arc fault or wiring issue

Error codes vary by manufacturer. Refer to the user manual or the manufacturer’s support portal for the exact meaning. Insulation faults and arc faults should always be investigated by a qualified electrician.

Immediate Checks You Can Safely Perform

There are a few simple issues you can safely rule out yourself:

• Check the circuit breaker and residual current device (RCD/GFCI) in the electrical distribution board and reset them if necessary.
• Ensure that both the AC and DC isolator switches on the inverter are in the On position.
• Perform a controlled restart: switch off the AC side first, then the DC side, wait a few minutes, and switch the system back on in the reverse order.

Warning: Never open the inverter housing yourself. Dangerous voltages may remain inside even after the unit has been switched off. Repairs must only be carried out by a qualified electrician. Unauthorized work will void the warranty and may pose a serious risk of electric shock.

Why Inverters Fail

Common causes of inverter failure include:

• Wear and ageing of electrolytic capacitors after many years of operation.
• Overheating due to dust buildup, poor ventilation, a hot installation location, or clogged cooling fans.
• Moisture ingress and weather-related damage.
• Power surges, particularly following a lightning strike.
• Less commonly, software issues that can often be resolved with a firmware update or system restart.

Repair or Replacement?

Whether a repair is worthwhile depends primarily on the age of the inverter and the nature of the fault. If the defect is clearly identifiable and the unit is relatively new, repairing it is usually the most cost-effective solution.

However, if repair costs exceed approximately 40% of the price of a new inverter, or if the unit is 12 to 15 years old, replacement is generally the more economical option. Modern inverters are more efficient, come with a new manufacturer’s warranty, and hybrid models can be prepared for the future addition of a battery storage system. If your inverter model has been discontinued, obtaining spare parts may also become difficult, making replacement the better long-term investment.

Repair and Replacement Costs

PV System Size	Inverter Cost	Notes
3–5 kW	Approx. €800–€1,500	Typical residential system
5–10 kW	Approx. €1,200–€2,500	Most common residential size; hybrid inverters approx. €2,000–€4,000
Over 10 kW	From approx. €2,500	Depending on specifications

In addition to the inverter itself, you should budget approximately €400–€800 for removal, installation, and commissioning by a qualified installer. A repair, including inspection and replacement of faulty components, typically costs between €150 and €800.

If you’re considering replacing your entire solar system instead of just the inverter, see our detailed guide on the cost of a 10 kWp solar PV system for a complete investment overview.

Warranty, Statutory Rights, and Insurance

Before authorizing any repair, determine who is responsible for covering the cost:

• Statutory warranty: In many cases, the seller is liable for manufacturing defects during the first two years after purchase (subject to applicable local consumer protection laws).
• Manufacturer’s warranty: Many manufacturers offer warranties of 5, 10, or more years. Covered units are often replaced quickly under warranty.
• Insurance: Damage caused by lightning or power surges is frequently covered by homeowners’ insurance or a dedicated PV insurance policy. Document any resulting damage and report the claim promptly.

Faulty Inverter in Hanover and the Surrounding Area

As a photovoltaic specialist based in Hanover, PVPro Solar provides fast, manufacturer-independent support. We inspect your PV system on site, identify the root cause of the fault, and give honest advice on whether a repair is worthwhile or whether replacing the inverter with a modern model is the better solution. Our goal is to get your solar system back to full performance as quickly as possible.

Visit PVPro Solar, call us on +49 511 3360603, or email us at hallo@pvprosolar.de.

How can I tell if my inverter is faulty?

Common signs include a complete loss of power generation, significantly reduced output, red warning lights or error codes, unusual operating noises, or an inverter that repeatedly restarts or has a blank display.

Can I replace the inverter myself?

No. The installation and electrical connection must be carried out by a qualified electrician. Unauthorized work is dangerous and may void your warranty and insurance coverage.

How much does it cost to replace an inverter?

Depending on the system size, inverter prices typically range from €1,200 to €2,500, with installation costs of approximately €400 to €800.

How long does an inverter repair take?

Minor faults can often be resolved quickly. If replacement components are required, repairs typically take 6 to 9 working days, depending on parts availability.

Will insurance cover damage caused by a lightning strike?

In many cases, lightning and power surge damage are covered by homeowners' insurance or a dedicated photovoltaic insurance policy. Check the terms of your policy and document the damage thoroughly before submitting a claim.