Off-grid when grid voltage is too high

Been thinking about this a lot lately after chatting to a neighbour who's on the grid and keeps seeing his SolarEdge cut out on bright summer days.

His street voltage was sitting at 257V last July — measured it myself with a clamp meter out of curiosity. That's above the EN 50160 upper limit of 253V, and sure enough his grid-tie inverter was tripping out precisely when he should have been generating the most.

It got me wondering — is this becoming more common in rural UK areas as more neighbours add solar? The DNO infrastructure clearly wasn't designed for this level of distributed generation.

For those of us who've gone full off-grid (or hybrid), this is actually one of the unsung benefits nobody talks about. My Victron Multiplus-II on the static caravan doesn't care what the grid is doing — it just cracks on with whatever the Pylontechs and the panels are providing. No voltage trip-outs, no lost generation windows.

If you're running a hybrid setup though, it's worth knowing your inverter-charger's tolerance thresholds. Victron lets you tweak the AC input voltage range, which is handy if you want to stay grid-connected but only on your terms.

Curious whether anyone here has actually measured their grid voltage and found it creeping high during summer? Particularly interested if you're in a rural area with lots of solar installations nearby — I suspect the problem is worse than people realise.

Worth considering for anyone still on the fence about cutting the cord entirely. Sometimes the grid isn't the reliable backstop it's cracked up to be. 🔌

@Pylontech_Queen this is more common than people realise, especially in suburban areas with lots of solar exports pushing voltage up.

Worth knowing that G98/G99 compliance means grid-tied inverters must disconnect above 253V (nominal 230V +10%). It's a legal requirement, not a fault.

The fix your neighbour probably needs is to contact his DNO — they're actually obligated to investigate and resolve high voltage complaints. Keep a log with timestamps first though, makes the complaint much stronger.

For those of us with off-grid or hybrid setups (my Victron Multiplus handles this brilliantly), you can set a wide AC input acceptance window and the battery just picks up the slack when grid drops out. Makes high-voltage events almost invisible operationally.

Has your neighbour checked whether his SolarEdge settings allow any voltage tolerance adjustment? Some installers leave headroom on the thresholds.

What @ExTrucker73 says rings true — I saw exactly this in my garden office setup last summer. My Victron Multiplus was tripping out on over-voltage protection repeatedly on sunny afternoons, logging 256-258V before it disconnected.

The fix that actually worked for me was tightening the AC-in high voltage threshold down rather than up — essentially forcing the Multiplus to island sooner and lean harder on the battery/solar rather than importing. Counterintuitive but it meant the grid became a last resort rather than first call.

Worth your neighbour checking whether his SolarEdge has adjustable trip thresholds too — some firmware versions allow it, though the DNO settings are often locked. Ultimately though, a proper off-grid or hybrid setup sidesteps this entirely. The grid's voltage management in areas with heavy rooftop solar genuinely hasn't kept pace with the rollout.

Good thread this. Worth mentioning that the DNO actually has an obligation under Engineering Recommendation G5/5 to keep supply voltage within ±10% of 230V, so 257V is technically within spec but only just. If your neighbour's seeing regular dropouts it's worth formally logging complaints with his DNO — they're often more responsive than people expect once there's a paper trail.

From an off-grid angle, one genuinely underappreciated benefit of going fully islanded is that your inverter sets its own reference voltage. My Victron runs a rock-solid 230V regardless of what the street's doing. No curtailment, no nuisance tripping.

@AndyButler — did your Multiplus eventually settle after a firmware update or did you end up adjusting the upper voltage threshold manually? Curious whether the defaults have improved lately.

Great thread. My narrowboat spends winters on the towpath in a marina with genuinely terrible shore power — voltages swinging between 253V and 261V some evenings when everyone plugs their kettles in simultaneously.

My Victron Multiplus-II has a configurable upper voltage threshold (adjustable via VE.Configure) and I've set mine to disconnect at 255V. Saved me more than once.

The often-overlooked trick: once you've disconnected from grid, your battery and solar can carry the load seamlessly if your system's properly sized. Effectively becomes an unintentional islanding test, which is rather good practice for genuine emergency backup scenarios.

@PeteGreen84 is right about DNO obligations — worth actually logging your high voltage events with a simple data logger and formally complaining. DNOs tend to act faster once there's documented evidence rather than just a phone call from an irritated homeowner waving their arms.

Decent thread this. Got similar grief on my boat last summer — marina shore power sitting at 261V on a hot afternoon and the Victron just said "no thanks" and switched to inverter mode. Frustrating at the time but actually it behaved exactly as it should.

What I want to know is: does anyone actually bother logging their grid voltage properly over time, or just rely on what the Cerbo GX captures when something goes wrong?

Also — @PeteGreen84 mentions the DNO obligation, but in practice how do you actually force them to do something? Complained to my DNO twice and got precisely nowhere. Is there a formal escalation route that actually works, or is it just Ofgem and good luck to you?