Fronius state 240/241 arc detection: what it means and what to do

Common causes

• Poorly connected plug connections on a solar panel.
• Poor or defective cable connections on the panel side.
• A defective panel, for example a problem in its junction box or a high-resistance solder connection in a cell.
• Cables incorrectly connected to the inverter's input terminals.
• Storm damage or another problem with the panels, which Fronius names as a possible reason for these codes.

Safe steps to try

1. Leave the system exactly as it is Do not press any buttons to clear the code. Do not open the inverter, a disconnect, a junction box or any conduit, and do not touch the panels, racking or wiring.
2. Note the code and any recent events Write down the state code and whether there was a storm, hail or work on the roof recently. Fronius says these can be the reason for arc detection codes.
3. Contact your installer or a technician This is Fronius's own instruction for codes 240 to 243. The technician checks the panels and DC wiring and resets the code once the cause has been dealt with.

Frequently asked questions

Why can't the inverter restart on its own?

Fronius designed it that way: after a serial arc is detected, the state code must be manually reset before the inverter feeds power again. The manual reset makes sure someone looks at the system first.

My system has optimizers. Does that matter?

It can. Fronius notes that power optimizers and other module-level electronics can affect how well the inverter's arc detection works, and that the installer is responsible for making sure it functions correctly in such systems.

Other Fronius faults

• Fronius state 107 no AC grid detected: what it means and what to do
• Fronius state 307 or 306 PV voltage low: what it means and what to do
• Fronius state 509 no power fed in: what it means and what to do
• Fronius state 475 insulation error: what it means and what to do