Grid voltage has remained persistently above the G98/G99 upper limit (253V). Unlike Error 300 which may be intermittent, Error 305 indicates a sustained condition.
Common causes
DNO supply voltage chronically high (common in rural UK areas)Voltage rise from nearby large PV exports on a weak networkExport limit set too high for local grid capacity
What to check
STEP 1
Log grid voltage over 24 hours using ShinePhone or a power quality logger. Note peak voltage and time correlation with solar generation
STEP 2
Enable Active Power Control in ShinePhone to reduce export and lower voltage rise. Set an appropriate export limit for the site
Escalate if
Supply voltage consistently above 253V at times of zero solar export -- this is a DNO supply quality issue, report and log all events
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