Diagnosing Fronius Symo inverter

My friend has a Fronius Symo 12.0-3 208-240 inverter (3 phase power onsite), hooked up to 56 (!) ground-mount 255W Trinasolar TSM-255PD05.05 solar panels ~= 14,280 DC Watts.

It recently stopped working, so I looked at its LCD and it reports “error code 317: Unbalanced intermediate circuit voltage. Submit a maintenance service request to your installer.” I found ONE reference to “intermediate circuit voltage” and it implies that the power between the DC and AC PCBs is at fault.

I opened it up and I see no physical abnormalities (no bulging caps, no thermal discoloration of the PCB), but the power ICs (i.e. FETs) are hidden behind what I can see.

System is visible here: https://www.google.com/maps/place/Ligara+Farms/@37.131566,-121.6205428,173m/data=!3m1!1e3!4m6!3m5!1s0x8091df787ff49091:0xbd7f1f440dbab6f5!8m2!3d37.1304206!4d-121.6200103!16s%2Fg%2F1tk63c6x?entry=ttu

Photos: https://photos.app.goo.gl/BhfforLEdin4RmrX9

The original installer is gone, so I found 3 Fronius factory reps “nearby” (one is as far as 4-5 hour drive away), and two of them have already suggested emailing the company themselves for debugging/diagnosing.

I’ll be emailing them later today, but I thought I’d start with this opening post, and keep y’all updated with the saga.

Worst case, looks like about a $3000 inverter to swap out.

Fronius typically offer a 10 year warrentee so if it’s within that period and the original installer is gone I’d contact them directly.

Two of the three “local” Fronius factory reps responded and suggested I email support. After half a dozen emails with added pictures (interior, error 317, serial number), they are sending me a whole inverter! I just need to transplant the display / control board, and then clip the entire inverter into place. No wiring required!

Hopefully we’ll be back online in a few days!

That is the advantage of there clip-on approach to inverters.

Did the replacement inverter fix the problems?

Sorry for the delay. I only visit the site about once a week, so things don’t happen too quickly.

A week ago we installed the replacement. It took a little reconfiguring, but it’s up and running now, generating a hair over 12 kW AC!

Interestingly, the feed may be 3 phase power, but from neutral, I measure 120, 120, and 240v. Not your typical 3*120v, which seems weird to me. Shrug. Configured for 208, it refused to start. Measured, saw the above, reconfigured for 240, and it was happy.

Ridiculously detailed instructions: Turn off AC disconnect. Turn off dc disconnect. Wait 5 minutes (i.e. go fetch replacement; it’s 110 lbs!). Unscrew lower panel. Unplug rj45 data cable. Unscrew main cover. Unscrew two screws at bottom attaching inverter to mounting plate. Pulling on the bottom swivels it off the connectors. Two person lift to swivel it out say 20 degrees, then lift off the pivot built into the top of the unit. Reverse process, but also swap the covers; the replacement came with a “shipping only cover”. Main menu, press the “Esc” button 5 times. Access code 73887, select country setup, (eventually) chose the 240V with neutral. Wait 5 minutes, and presto, sunlight becomes AC energy!

TBH, I’m surprised they didn’t try to save shipping by only sending me boards (the metal cover alone weighs a bunch, as does the “empty” (no pcb, just the steel) mounting bracket they shipped, but it would’ve been an ordeal to remove all the boards, upgrade the firmware, and reinstall everything properly (read: they have torque specs, I’m sure!). 110 lbs costs a pretty penny these days. for a warranty swap, no less. Aside from my time, this is basically costing nothing (aside from high PG&E bills, about $1k/mo!)

Compare this with Enphase who requires that warranty be processed through a registered dealer. My mom pays $165/hr for this privilege. However, neither she nor I are going to be climbing on the roof and lifting panels to replace inverters, so we’d be hiring them anyways. Her place has lightning, rain, wind, and a slippery metal roof.

Maybe High-leg delta - Wikipedia wiring for the interconnect?