3 phase Multi RS Solar 6000 A443 error 59 V1.30

Interesting one this — been keeping an eye on similar threads over on the Victron community forum and error 59 (ACIN relay test failure) seems to crop up more than it should on the Multi RS Solar units, particularly after firmware updates.

I'm only running a single-phase setup in my shepherd's hut, so I can't speak directly to the 3-phase headaches, but I had a relay-related fault on my older MultiPlus II that turned out to be nothing more dramatic than a dodgy AC input connection causing intermittent contact resistance. Victron's diagnostics saw it as a relay failure when the hardware itself was actually fine.

For anyone hitting this on v1.30 specifically, worth asking:

• Did the error appear after the firmware flash or a few days/weeks after, as in the case above?
• Is your AC wiring solid — particularly the N-PE connections which can cause relay test failures even when everything looks right?
• Have you tried rolling back to the previous firmware via VRM to see if it's reproducible?

The 3-phase configuration adds another layer of complexity because all three units need to pass the relay test essentially in sync. If one unit has even slightly marginal AC input conditions, it can cascade.

Would be curious whether anyone's had Victron actually replace a unit under warranty for this, or whether a firmware fix eventually sorted it. Seems like it could go either way — hardware fault or a bug in how v1.30 handles the relay test sequence under ESS mode.

Anyone else seeing this on UK installs? Particularly interested if it's happening off-grid with a generator as the AC input rather than grid.

@SaltyHiker had a near-identical situation with my cabin setup last winter — woke up one morning to the Multi RS Solar throwing error 59 and initially assumed it was a duff unit.

Turned out the AC input relay test is extremely sensitive to the quality of the incoming supply. In my case, a dodgy MCB on the distribution board was introducing just enough resistance to flunk the relay test at startup. Swapped it for a decent Hager unit and it cleared immediately.

Worth checking:

• AC cable sizing — undersized cabling causes voltage drop that mimics a relay fault
• Neutral-earth bond at your supply origin
• Whether it's consistently error 59 or only on cold mornings (thermal expansion on corroded terminals is a real culprit)

The Victron community thread is useful but a lot of those installs are 50Hz European rather than proper UK grid arrangements, so some advice doesn't translate directly.

Error 59 on the Multi RS Solar is basically the unit saying "I don't trust your grid connection" — usually worth checking your AC input wiring integrity before blaming the firmware, as loose neutrals are the silent killer on these units.

On my narrowboat setup I've seen relay test failures triggered by a dodgy shore power connector causing micro-interruptions the unit detects during the self-test cycle — swapped the inlet and never saw it again.

That said, V1.30 did have some known quirks; worth cross-referencing with Victron's changelog to see if a newer firmware addresses it before you start pulling terminals apart. The Victron community forum usually has the most current firmware release notes directly from the devs.

Worth noting this can also rear its head on 3-phase setups specifically because the relay test runs across all three phases — if one leg has even slightly marginal wiring (loose terminal, undersized cable run) the unit can fail the test intermittently rather than consistently, which makes it a nightmare to diagnose.

On my boat I had something vaguely similar with a different Victron unit throwing relay faults that only appeared at certain load conditions. Turned out to be a connection that looked fine visually but had high resistance under load.

If you're on V1.30 firmware specifically, worth checking the Victron community forum for any known bugs on that version — I've seen a couple of threads suggesting the relay test parameters got tweaked between minor revisions and some installs that were borderline suddenly started failing.

@OddJobBob60 makes a fair point — had my single-phase setup throw a wobbly last spring and it turned out the neutral-earth voltage was drifting enough to spook the relay test, sorted it by tightening a dodgy connection in the consumer unit that I'd been ignoring since approximately the dawn of time.

@Pete1994 neutral-earth bond issues on Victron kit are like that one dodgy crew member on a narrowboat — everything's fine until you're mid-canal and suddenly nothing works.

Worth adding: if you've already ruled out the wiring, check whether a firmware rollback sorts it — A443 v1.30 has form for being that firmware that breaks things Victron quietly fixed in the next release without mentioning it in the changelog.