The inverter flags that the grid impedance at its connection point is above its limit. On the Conext CL125 this shows as event code 015, and on Solis inverters it shows as the alarm G- IMP. On SMA units the same grid incident covers either too high a grid voltage or too high an impedance, and the inverter disconnects from the utility grid, so AC output drops to zero. In monitoring data, a weak grid shows up as grid voltage rising with exported PV power. The inverter can trip when the voltage reaches the threshold at high yield, and hourly averages may hide these trips. On the CL125, first check that the AC cable type and size and the transformer impedance match the CL125 Solution Guide or local regulations. Then let the inverter recover automatically. For plants with many paralleled inverters, Schneider recommends limiting AC cable impedance and transformer impedance. It also recommends calculating grid impedance at the point of common coupling before design, and avoiding weak, high-impedance grids. On Solis units, the protection limit can be adjusted through the user-defined settings, but only if the electrical company allows it.
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- sentence 2: support check: partial - SMA text states voltage or impedance too high and disconnection from the grid, but AC output dropping to zero is only implied.
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c1 verified · fact
Inverter fault code display
Conext CL125 reports event/alarm code 015 (hex 0x000F), described as grid impedance above the inverter's limit; Solis inverters show the alarm G- IMP, described as high grid impedance.
verified by: review-workflowverified on: 2026-10-23
c2 verified · fact
Grid voltage rise with power
Plotting grid voltage against PV feed-in gives a positive slope, and linear regression of that slope estimates the equivalent grid impedance. On a weak grid the voltage approaches the trip threshold of 1.1 p.u. at high yield, and the inverter trips. Hourly averages can hide these trips.
verified by: review-workflowverified on: 2026-10-23review note: support check: partial - Positive slope, regression for impedance, 1.1 p.u. trip and hourly averages hiding trips are stated, but the passages don't link high impedance to specific phase voltage/W signal patterns, and nothing is said about approaching the overvoltage limit at 'high output' with W 'sudden trip to zero' beyond the immediate trip.