You should replace your inverter if:

• The inverter is faulty and repair is no longer possible or cost-effective.
• Yield decreases noticeably, while the solar panels are still functioning well.
• The inverter is older than 10-15 years, because newer models are often more efficient and offer better monitoring.

Replacement may pay off if you switch to a more energy-efficient or smarter inverter, for example, with battery support.