Growatt Error 203: PV Isolation Low
Error 203 (PV Isolation Low) means the Growatt measured low insulation resistance between the DC (solar panel) wiring and ground. In plain terms, it suspects a ground fault: current that could leak to earth. It is a safety check, so the inverter stops. A brief Error 203 in damp weather is often moisture; a stubborn one points to a real insulation problem.
What usually causes Error 203
- Moisture or condensation in a DC connector, junction box or cable gland, common early morning or after rain. (A wet DC isolator is a classic cause.)
- Damaged or aged cable insulation letting current leak to ground.
- A grounding (PE) problem in the array or system earth.
- A faulty panel or junction with degraded insulation.
What to do, safely
Inspection is for the pros Measuring insulation and working on DC wiring is an installer job, and PV strings are live in daylight. Your safe role is to note the pattern and let it self-clear once.
- Note the pattern. Does it mainly show in the morning, after rain or in humid weather, then clear as things dry? That points to moisture and is common.
- Let it self-clear or power-cycle once. AC off, then the DC isolator, wait 5 minutes, restart. A moisture-driven Error 203 often clears as the day warms.
- If it persists, especially in dry weather, stop. A steady Error 203 is a genuine insulation or grounding fault. Don't keep resetting it.
- Call your installer. They measure the impedance between PV(+), PV(-) and ground, check the panel and inverter grounding, find the wet or damaged point, and fix it.
Quick decision flowchart
Error 203 appears
↓ does it clear as it dries, mostly in damp conditions?
✅ Yes → likely moisture. Keep an eye on it; mention at next service.
❌ No, persists or shows in dry weather → real insulation / ground fault.
↓
Persistent Error 203 needs an installer to measure insulation resistance and inspect the DC wiring and grounding.
When to bring in a professional
Insulation faults are a safety matter (leakage to ground). A persistent or dry-weather Error 203 should be inspected by a licensed installer, not cleared and ignored.
Related Growatt codes
FAQ
Error 203 shows every morning then clears. Is it serious?
That pattern usually means overnight moisture on the DC wiring that dries off. Worth reporting at your next service, but a brief morning Error 203 that clears is commonly moisture rather than a failing part.
Can I dry it out myself?
No. Locating and sealing a damp or damaged DC connection is qualified work on live DC wiring. Note the pattern and have your installer handle it.
Sources
- Growatt inverter user manual and error-code reference (Error 203 = PV isolation low; check grounding, measure impedance between PV(+)/PV(-) and ground).
- Growatt installer documentation.
⚠️ Safety disclaimer. A DC insulation fault is an electrical-safety issue. PV wiring is live in daylight. This guide covers noting the pattern and a single safe power cycle only. Inspection and repair must be done by a licensed installer or electrician.