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.
Deye Inverter Error F02/F24 — DC Insulation Impedance Fault Explained
F02 and F24 both mean your Deye inverter measured dangerously low insulation resistance between the solar array and earth — current may be leaking where it should not. The inverter refuses to start, which is exactly the safe response. Do not touch the equipment; this fault belongs to your installer.
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?
Is your system producing power right now?
What this code means
Your solar array operates at hundreds of volts DC, and every part of it — panels, cables, connectors — is supposed to be electrically isolated from earth. Your Deye inverter continuously measures that isolation as “insulation impedance.” If the resistance between the DC conductors and ground drops too low, current has a path to leak out, which is a shock hazard and a fire risk.
F02 (“DC insulation impedance permanent fault”) and F24 (“DC insulation impedance failure”) are two labels for this same condition on different Deye model families — F02 appears in the string-inverter manuals, F24 on the hybrid and newer lines. The word “permanent” in F02 does not mean the damage is permanent; it means the fault latches and will not clear until the underlying problem is fixed.
When the impedance drops below the safety limit, the inverter will not connect to the grid — full stop. Deye’s own notes say this problem is “caused by the PV side usually,” meaning the culprit is almost always out on the roof or in the wiring: a damaged panel, a wet connector, abraded cable insulation, or a compromised ground connection. Moisture is the classic trigger, which is why these codes love to appear after rain.
What is this downtime costing you?
Rough estimate while your system isn't producing. Adjust the numbers to match your setup.
≈ – 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 in connectors, junction boxes, or cable runs — the single most common trigger. Water lowers insulation resistance dramatically, which is why the fault often appears after rain and clears as things dry.
- A damaged solar panel — cracked glass, delamination, or a failed backsheet can create a leakage path from the cells to the panel frame.
- Abraded or pinched DC cable insulation — cables rubbing against mounting rails or the roof can wear through to bare conductor.
- A compromised grounding connection — Deye’s own remedy starts with checking the inverter’s grounding cable, plus the panel frames’ ground path. A loose or corroded ground makes a small leak look worse and removes a layer of protection.
- Deteriorated connectors — UV-aged or poorly crimped MC4 connectors that let water in.
Safe steps to try
Work top to bottom, ticking off each step as you complete it. 0 of 5 done.
Is your inverter still under warranty?
Before paying for a repair, check — your installer may fix this free.
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 solar installer if F02/F24 persists in dry weather, returns repeatedly, or never clears after a restart. Your installer needs to insulation-test each string (a “megger” test), locate the damaged panel, cable, or connector, and verify every grounding connection — work that involves live DC at lethal voltages. Treat it as urgent — same day — if you notice a burning smell, see visible damage or arcing, or feel any tingling when near the equipment: shut the system down using the manual’s stop procedure, keep everyone away, and call a professional immediately.
Frequently asked questions
What is the difference between F02 and F24?
The underlying condition is the same — low insulation resistance between the array and earth. F02 is the label used in Deye’s string-inverter manuals (“permanent fault” meaning it latches until fixed), while F24 is the label on hybrid and newer models (“impedance failure”). Different display text, same problem, same response: call your installer.
Why did this appear right after it rained?
Water is the classic trigger. Moisture inside a connector, a junction box, or a hairline crack in a panel creates a conductive path to earth that was not there when dry, dropping the insulation resistance below the trip point. Morning dew and heavy rain are the two most common accomplices.
Can I just wait for it to dry out and ignore it?
A one-time trip that clears in dry weather and never returns is usually just moisture. But if it happens more than once, something is letting water in — a cracked panel, a failing connector seal, damaged cable insulation — and that degrades over time. Report every occurrence to your installer.
Is it safe to touch the inverter while F02 is showing?
No. The whole point of the fault is that current may be leaking to parts of the system that should be safe to touch. Treat the inverter, cables, and mounting hardware as potentially live until a professional has verified otherwise.
Will F02/F24 damage my panels?
The fault itself does not damage anything — the inverter caught the problem and refused to operate. But the underlying cause, like a cracked panel or chafed cable, will get worse if ignored and can eventually become a fire or shock hazard. That is why the code deserves a prompt installer visit.
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 — Deye SUN-(20-35)K-G02-LV User Manual Ver 2.0 (deyeinverter.com): F02 — DC insulation impedance permanent fault, remedy: check the grounding cable of inverter. Deye SUN-(7.5-10)K-G User Manual Ver 2.0 (deyeinverter.com): F24 — DC insulation impedance failure, remedy: check PV panel connections and restart inverter; notes the problem is usually caused by the PV side. Deye SUN-(40-50)K-G-LV User Manual Ver 2.0 (deyeinverter.com): F24 detail — check panel frame grounding, inverter grounding, and AC/DC cables for shorts to ground or damaged insulation.