Solis PV-ISO-PRO: Low PV Insulation
PV-ISO-PRO (low PV insulation protection, code 1033) means the Solis measured low insulation resistance between the DC (solar panel) wiring and ground, in other words a possible ground fault. It is a safety check: if current could leak to earth, the inverter stops. A brief one in damp weather is often moisture; a stubborn one points to a real insulation problem.
What usually causes PV-ISO-PRO
- Moisture or condensation in a DC connector, junction box or cable gland, common early morning or after rain.
- 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 Working on DC wiring and grounding 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 one often clears as the day warms.
- If it persists, especially in dry weather, stop. A steady PV-ISO-PRO is a genuine insulation or grounding fault. Don't keep resetting it.
- Call your installer. They measure the PV-to-ground resistance (it should be well above 20 kΩ), check the AC neutral and ground, and find the wet or damaged point.
When to bring in a professional
Insulation faults are a safety matter (leakage to ground). A persistent or dry-weather PV-ISO-PRO should be inspected by a licensed installer, not cleared and ignored.
Related Solis codes
FAQ
PV-ISO-PRO 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 event that clears is commonly moisture rather than a failing part.
Can I fix the moisture 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.
Helpful guides
Sources
- Solis inverter alarm-code list (PV-ISO-PRO = low PV insulation; measure PV-to-ground resistance, check AC wiring, update firmware).
- Solis 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.