We're currently experiencing limitations on our inverter output that are a direct result of grid voltage variations that are our lines company's doing.
To background our situation we are located in a rural area so grid anomalies are an expected part of life. We installed an upgrade to our system in August 2023 and soon found that the inverter (an 8.2kW Fronius Primo single phase) was shutting down intermittently due to its detecting grid voltage variations. The inverter monitors export levels and throttles to comply with our 5kW export cap. As a result of the issues we had our installer increase the inverter's operating grid voltage parameters on Fronius's instruction. Problem solved.
In the last couple of months our lines company, Powerco, installed upgraded transformers and voltage regulating equipment in our area. Since then we have noticed that the inverter spends most of the day displaying a "Notice: State 567" which indicates a grid frequency issue. In addition I have noted that the inverter isn't reaching its maximum output capacity of 8.2kW but only ~7.5kW. We have 9.5kW of panels on it and an 8.2kW output was a near constant last summer. Also the export cap isn't being reached and is typically ~4kW despite 5kW being potentially available. Also the inverter output is falling short even when we're charging an EV which leaves only small residual generation for export.
The word from our installer and Fronius Australia who can both see our inverter data is that the unit is reducing its output due to excessive grid voltage (up to 246.5V) in order to prevent contributing to a problem there. This diagnosis fits exactly with the behaviour I'm seeing on the inverter. I'm currently waiting for a callback from Powerco as the staff member was in a meeting when I rang them earlier today.
From what our installer is saying I expect to be flicked off by Powerco but the light at the end of the tunnel is that upcoming changes in NZS4777 will permit us to widen our inverter's grid voltage parameters when that occurs to +/-10% rather than the current +/-5% which will solve the problem. In the meantime our peak generation period over summer will be clipped by Powerco's issues.
So, in essence we're suffering output restrictions due to the malfunctioning of Powerco's infrastructure despite having to comply with their export cap and other installation regulations. Is there anybody else out there that are experiencing similar issues in their (rural?) location?