Critical What does this mean?

A safety-rated fault — there may be a risk of electric shock, fire, or equipment damage. Do not try to fix this yourself. Call a qualified electrician.

Growatt PV Isolation Low: Meaning, Causes & Safe Fix

PV Isolation Low means the insulation resistance between your solar panels and earth has dropped too low — a potential shock hazard. Treat this seriously and get professional help.

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?

What this code means

Your inverter constantly measures the insulation between the DC solar-panel wiring and earth. 'PV Isolation Low' means that insulation has degraded — current could be leaking where it should not. Because this is a shock-safety system, the inverter shuts down immediately.

What is this downtime costing you?

Rough estimate while your system isn't producing. Adjust the numbers to match your setup.

System size (kW) Peak sun hours / day Electricity rate ($/kWh)

–per day

–per week

–per 30 days

≈ – 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

Moisture or water ingress in panels, connectors, or DC cabling (most common — often appears after rain or on damp mornings)
Damaged or degraded panel or cable insulation
Poor grounding of the panels or the inverter
Aging panels with degraded backsheet insulation

Safe steps to try

Work top to bottom, ticking off each step as you complete it. 0 of 5 done.

Do not touch the panels, DC cabling, or inverter more than necessary.
Note when the error appears — Growatt's manual specifically asks whether it happens in damp conditions.
From a distance, check whether any DC isolator or breaker looks wet or damaged (do not touch it).
Wait for dry conditions and see if it clears — but still report it to your installer.
Keep a record of dates and times for your installer.

Is your inverter still under warranty?

Before paying for a repair, check — your installer may fix this free.

Brand Year installed

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 promptly — this is a shock-safety fault. If it appears in dry conditions, persists, or you see any damage or moisture around the equipment, call immediately. Insulation testing requires a professional with proper test equipment.

Frequently asked questions

Is PV Isolation Low dangerous?

It can be — it means the safety insulation between high-voltage DC wiring and earth is compromised. The inverter shuts down to protect you, but the underlying leak needs professional diagnosis.

Why does it happen after rain?

Moisture is the most common cause. Water in a connector, a cracked panel backsheet, or damp cabling can all drop insulation resistance. It often clears as things dry — but recurring episodes mean something needs fixing.

Can I hose down my panels to check?

No — never spray water on electrical equipment while troubleshooting an insulation fault. Leave wet-condition diagnosis to your installer.

Need a professional?

This fault is a safety risk — do not attempt to fix it yourself. Contact a qualified solar electrician in your area.

Sources: meaning and troubleshooting verified against the manufacturer's documentation — Troubleshooting for Growatt TL&MTL (Ver1.2) 2013-7-15, Growatt New Energy ("The inverter's PV input insulation impedance is too low"); corroborated by GROWATT MIN 7000TL-X User Manual (Error 203: 'Insulation problem')