FAQ
TL;DR: 30 mA RCDs are 3× more sensitive than 100 mA; "For inverters, a differential with a leakage current of 100 mA is recommended." Recurrent Sofar Grid OVP/UVP/OFP/UFP with RCD trips usually indicates leakage on the inverter circuit. [Elektroda, kosmos99, post #19115414]
Why it matters: This helps Sofar PV owners quickly stop nuisance trips, recover uptime, and fix safety-critical wiring or grounding issues.
Quick Facts
- OVP/UVP/OFP/UFP codes flag out-of-range AC voltage or frequency conditions on the grid. [Elektroda, 3301, post #19116524]
- Sofar may also show these codes when the AC side is disconnected. [Elektroda, prose, post #19116594]
- Use a dedicated RCD for the inverter circuit; avoid mixing with house loads. [Elektroda, kosmos99, post #19115748]
- Typical choice: 100 mA RCD; a 30 mA device is 3× more sensitive. [Elektroda, kosmos99, post #19115414]
- Pull trip data from the inverter’s Export tab to correlate faults with grid values. [Elektroda, 3301, post #20541923]
What do Sofar Grid OVP, UVP, OFP, UFP codes actually mean?
They signal grid voltage or frequency outside allowed limits. OVP/UVP are voltage, and OFP/UFP are frequency. One expert explains, "Grid OVP, UVP, OFP, UFP means too high and too low AC voltage and too high and too low frequency." Check grid conditions when the fault appears. [Elektroda, 3301, post #19116524]
Why does my 30 mA RCD trip whenever these errors pop up?
RCD tripping indicates leakage current on the inverter circuit. A 30 mA device is three times more sensitive than a 100 mA one, so it trips sooner. The thread notes leakage as a likely cause during these faults. Address wiring, insulation, and the inverter’s connection. [Elektroda, kosmos99, post #19115414]
Should the inverter be on its own RCD?
Yes. Put an extra RCD only on the inverter circuit. This isolates inverter leakage from household circuits and reduces nuisance trips. As one expert says, "An extra one should only be added to the inverter circuit." Verify the installation integrity as well. [Elektroda, kosmos99, post #19115748]
Which RCD rating should I choose for a PV inverter, 30 mA or 100 mA?
Many inverters work better with a 100 mA device to avoid nuisance trips from normal leakage currents. "100mA is recommended for some inverters." Always follow the inverter manual and local code before changing protection. [Elektroda, prose, post #19118004]
Where should the inverter connect relative to the main RCD?
Connect the inverter supply before the main residual current device, with proper overcurrent protection. This arrangement helps prevent the house RCD from tripping on inverter events. Confirm compliance with local regulations. [Elektroda, 3301, post #19116524]
How do I use Sofar logs to find why it shut down?
Export and correlate data with the shutdown time.
- Open the inverter’s Export tab and download AC parameters.
- Note the exact time of each shutdown.
- Compare grid voltage and frequency at those times to limits.
This pinpoints a grid versus installation issue. [Elektroda, 3301, post #20541923]
Can a miswired neutral (N) cause nuisance RCD trips?
Yes. Incorrect neutral pairing or mixing neutrals across RCD-protected circuits can cause false trips. Inspect the RCD wiring, especially the neutral path, and correct any cross-connections. This is a common installation error with inverter additions. [Elektroda, Cytro12, post #19118908]
I see Grid OVP/UVP/OFP/UFP when sun bursts through clouds, but no RCD trip. What then?
The inverter is detecting out-of-range grid conditions. Export inverter data and verify the grid voltage and frequency at those moments. Correlate trip time with values to confirm a grid transient. This evidence guides your installer or utility. [Elektroda, 3301, post #20541923]
Could replacing the inverter fix persistent trips and errors?
Sometimes. One user resolved repeated issues by replacing the Sofar unit with a new model running newer firmware. Hardware or software updates can stabilize protection behavior. Verify root cause first to avoid unnecessary swaps. [Elektroda, bobo 44, #19299204]
Will changing RCD sensitivity solve the problem?
Changing the RCD alone can mask an underlying fault, such as insulation damage or N-PE issues. Have the installer confirm your network type and wiring per the inverter manual. Fix the cause before altering protection. [Elektroda, Cytro12, post #19117915]
Two inverters trip different RCDs randomly. What should I check first?
Give each inverter its own RCD and verify the installation. Shared or mixed circuits escalate leakage and trip risks. The advice is clear: add an extra RCD only to the inverter circuit, then validate wiring and the inverter. [Elektroda, kosmos99, post #19115748]
Do these grid error codes also show up if AC is disconnected?
Yes. A user verified that Sofar displays these codes when the AC side is cut. "In Sofar, such errors appear when the AC is disconnected." This is an expected edge case and not necessarily a fault. [Elektroda, prose, post #19116594]
Is a 30 mA RCD acceptable with a PV inverter?
Some systems run fine on 30 mA, provided grounding and wiring are correct. One user reported no issues using 30 mA after checking installation and earthing. If nuisance trips occur, investigate leakage and connections. [Elektroda, Cytro12, post #19115915]
What info should I share to get fast help from installers or forums?
Post clear photos of the AC/DC boxes near the inverter and the switchboard. Include RCD ratings, wiring routes, and the inverter’s error log timestamps. Visuals accelerate diagnosis and reduce guesswork. [Elektroda, noja102, post #19116147]
