Check & restart

Deye F20: DC Overcurrent Fault (Hardware)

Updated June 2026 · Reviewed for technical accuracy · ~3 min read

F20 means the inverter sensed too much current on its DC side (the solar panel and battery side) and shut down to protect the hardware. It's the DC cousin of F18. Common triggers are a wiring issue on the PV or battery input, or, in off-grid mode, demanding more power than the system can deliver at once.

Is it the panels, the battery, or the load?

A PV or battery connection problem. A loose, wrong, or reversed DC connection on the input side.
Too much demand in off-grid mode. The load is pulling more than the battery/inverter can supply, spiking DC current.
A one-time surge that the protection caught.
Rarely, an internal hardware fault if F20 keeps returning with everything correct.

The safe fix, step by step

Before you start Don't open the inverter or handle DC power terminals. Checking whether something was recently changed and reducing load are safe; physical DC wiring work is for your installer.

Reduce the load (off-grid mode). If you're running on battery/off-grid, switch off heavy appliances so the system isn't being pushed past its limit.
Note any recent changes. Did F20 start after new panels, a new battery, or wiring work? That points to a connection issue introduced then.
Power-cycle safely. Turn off the AC breaker, then the DC isolator, wait 5 minutes, then restart both.
Watch what happens. If F20 clears and stays gone with a sensible load, you're good. If it returns, stop and get the DC connections checked.

Quick decision flowchart

F20 appears

↓ reduce load (off-grid) & power-cycle

✅ Clears and stays off with sensible load → likely a transient or overload. Keep load within limits.

❌ Returns, especially with normal load → DC wiring issue or internal fault.

↓

If it keeps returning, have your installer check the PV and battery connections.

When to call a professional If F20 comes back after a proper restart, or you suspect a reversed or loose DC connection, that's an installer job. DC inputs are live and must be checked by a qualified person, don't keep resetting a returning DC overcurrent fault.

Related Deye codes

F18, AC overcurrent F26, DC busbar unbalanced F56, DC bus voltage low

FAQ

F20 happens when I turn on a big appliance off-grid. Why?

That's a classic overload trigger. A high-draw appliance spikes the DC current beyond the limit. Stagger heavy loads or check that your appliance demand is within the inverter and battery rating.

Could F20 mean my panels are wired wrong?

If F20 started right after install or panel work, a reversed or loose DC connection is a real possibility. Don't probe the DC wiring yourself; have the installer verify polarity and connections.

Is F20 the same as F18?

They're siblings: F18 is overcurrent on the AC (output) side, F20 is overcurrent on the DC (panel/battery) side. The mindset is similar: reduce stress, restart once, and if it returns, get it checked.

Sources

Deye Hybrid Inverter User Manual (F20 = "DC over current fault of hardware"; check PV and battery connections, reduce load in off-grid mode, power-cycle).
Deye dealer technical references for DC-side fault codes.

⚠️ Safety disclaimer. Solar inverters carry lethal DC and AC voltage even when "off", and PV inputs are live in daylight. This guide covers reducing load and a single safe power cycle only. DC wiring checks must be done by a licensed installer or electrician.