If you own an older solar system with a single central string inverter and it’s starting to fail, you have more options than just a straight swap. Here’s how to think through the decision.

Why Older String Inverters Fail More Often

String inverters were the dominant residential technology through roughly 2015, and a single unit handles the entire system’s DC-to-AC conversion. That centralization means more electrical stress running through one set of components — and it’s why string inverters typically show their first major failure between years 8 and 12, well before the panels themselves show any meaningful degradation. If you’re seeing error codes or reduced output, start with our Inverter Errors & Failures Troubleshooting Guide to identify what you’re dealing with, or find your specific brand: SolarEdge, SMA, Fronius, ABB/Fimer, Aurora, PVI, or SunPower.

Option 1: Repair

Viable when the inverter is a supported, actively-manufactured platform (SolarEdge, SMA, Fronius) and the fault is component-level — a fan, capacitor, or communication board — rather than a full internal failure. Repair is usually the lowest-cost path but makes less sense on discontinued platforms like Aurora or PVI, where parts are scarce.

Option 2: Direct Replacement (Like-for-Like)

Swapping in a new string inverter of similar specification is often the fastest and most cost-effective option when the rest of the system — panels, racking, wiring — is in good condition and you don’t need panel-level monitoring or added resilience.

Option 3: Upgrade to Microinverters

Replacing a failed string inverter with a microinverter setup (one small inverter per panel) means a single component failure only affects one panel instead of your entire system, and you gain panel-level production monitoring you likely didn’t have before. This is a larger project than a direct swap, but for homeowners already facing a full inverter replacement, it’s often the point where upgrading makes the most financial sense — you’re paying for labor either way.

Option 4: Upgrade to a Hybrid Inverter with Battery Storage

If you’ve been considering battery backup, a failed string inverter is a natural trigger point to move to a hybrid inverter that supports both grid-tied solar and battery storage in one unit, rather than replacing the failed inverter now and adding a separate battery inverter later. See our home battery storage page for what this involves.

How to Decide

  • System under 8 years old, single fault, supported platform → Repair
  • System 8-15 years old, out of warranty, straightforward failure → Direct replacement
  • Ready to add panel-level monitoring or expand the system later → Microinverter upgrade
  • Considering battery backup or already planning for one → Hybrid inverter upgrade

A proper diagnostic visit will tell you which category your situation falls into — and whether your existing wiring, panels, and roof-mounted components are in good enough condition to support whichever path you choose.

Related Reading

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Sources & Further Reading