What G98 actually requires at 253 V, and why an EU kit drops out first
1. The G98 protection settings
These are the settings a single-phase unit was type tested to under Engineering Recommendation G98/1-4:2019. They come from certificate of compliance U20-0161, issued on 18 March 2020 by Bureau Veritas Consumer Products Services Germany GmbH under DIN EN ISO/IEC 17065, report 16TH0371-G98/1_4, covering the SolarEdge SE2200H, SE3000H, SE3500H and SE3680H.
| Protection | Setting | Trip time |
|---|---|---|
| Over voltage, stage 1 | 262,2 V | 1,0 s |
| Over voltage, stage 2 | 273,7 V | 0,5 s |
| Under voltage | 184 V | 2,5 s |
| Under frequency, stage 1 | 47,5 Hz | 20 s |
| Under frequency, stage 2 | 47 Hz | 0,5 s |
| Over frequency, stage 2 | 52 Hz | 0,5 s |
Values are reproduced with the decimal comma the certificate itself uses. The second over voltage stage, 273.7 V, is the one that trips in half a second; the first allows a full second.
The certificate also records what happens after a trip: “At 266,2V — Confirmation that the Generating Unit does not re-connect: No reconnection”. A unit that has dropped out does not come straight back while the voltage is still high.
2. The test nobody quotes
Trip points are the part everyone repeats. The operating range test is the part that matters to a reader whose inverter keeps cutting out, and we have not seen it quoted anywhere. From the same certificate, verbatim:
Test 2 — Voltage = 110% of nominal (253 V), Frequency = 51,5 Hz, Period of test 90 minutes. Connection: Always connected. Limit: Always connected.
Read the limit column. The requirement is not that the unit survives 253 V. It is that it stays connected at 253 V, for an hour and a half, without interruption. 253 V is the top of the range the law allows — see the voltage section of our legal page for where that number comes from.
3. Where the EU device stops
The APsystems EZ1-M and EZ1-H are common in balcony kits. The European edition of the datasheet publishes the output range as:
Nominal Output Voltage / Range — 230 V / 184 V – 253 V
The range ends at the number a G98-certified unit has to keep working at for 90 minutes. That is the whole point of this page: the EU device stops where G98 requires a UK device to keep going. Whether that produces a problem for any given household depends on the supply, and that is the next section.
4. What this does not prove
Four limits on the above, stated plainly.
- We have not read Engineering Recommendation G98 itself. The ENA does not publish it openly. What we read is a type test certificate issued against it by an accredited body, which lists the settings the unit was tested to. That is one step removed from the standard.
- The certificate is dated 2020 and covers string inverters, not a balcony kit. G98 settings are a property of the recommendation rather than of the product, but that is an inference on our part, not something we read.
- The EZ1-M is one device. We use it because its range is published, not because it is the only one or because it is the one you own.
- Continental European standards set their own limits, and we have not verified those against a primary document. We are not quoting a number we cannot show you.
5. If your inverter keeps dropping out
If an inverter keeps disconnecting, two things can be true at once. The device may be configured to a range that ends lower than G98 allows. And the supply may genuinely be running high: the Energy Networks Association says so itself, and is consulting on lowering the statutory lower limit from 216 V to 207 V to give operators room below the 253 V ceiling. Establish the actual voltage at the socket across a day before blaming either.
The 800W ceiling is a separate question from the voltage one — see the 800W limit explained. If you have not yet told your network operator the unit exists, that is the G98 notification route.