Batteries no longer discharging to 20%, staying about 67%
(March 2024 - I have added an update at the end of this post) I have not changed the system mode settings since they were satisfactorily set in April 2023.
Screen snips taken shortly after showed correct performance, with charging up to SOC 80% during each of three off-peak periods and discharging to SOC 20% as required at peak times.
Puzzled why electricity bills have rocketed, I see that over the last few weeks (I can't get detail further back) the SOC was not going down to 20%. A month ago, it plateau-ed at 55%, next day 56%, then 57%, 58% etc., until yesterday 67%.
Here are the system mode settings I have not changed:
This was part of a typical day last year when everything seemed fine:
Then here is yesterday's crazy situation with SOC never going below 67%
I have contacted our installer, who said they'd contact Sunsynk, but so far no response. A system that cost thousands but which had theoretical pay-back within a year is no longer achieving savings on grid input. How does this get resolved, bearing in mind that I have not altered settings?
UPDATE: 2nd March. From 5th January, the system went steadily erratic, and at one stage, a Sunsynk employee set the sytsem to charge during a peak tariff period and left it like that for a week. More Sunsynk involvement was helpful, with firmware upgrades to inverter and all three batteries as well as WIFI dongle. Then an attempt to charge at 100 amp limit probably caused the Givenergy 100a DC breaker to deteriorate and showed more than 2v pd across the contactor poles, which was enough difference between v-bat and BMS voltage to shut down the inverter operation and it stayed at 62% SOC for a whole month before help resulted in the mcb being replaced, after which we forced charge to 100% and everything seemed to work fine with two charging cycles to 100% until less than a day later, the inverter has gone offline, it now being a weekend and nobody at installers or Sunsynk contactable.
FURTHER UPDATE: 2nd March. It looks like many UK users have similar OFFLINE problem and a Sunsynk tech post says that they are working to resolve the issue, so to try again in 24 hours.
Every day or so, the discharge settled at 1% higher than before. We worked with Sunsynk and the installers to get upgrades to software for dongle, inverter and batteries but it did not upgrade for the two slaves, so everything was reconfigured to isolate the master and use slave 1 as master and request fresh upate. Then master plus two slaves were wired back as before. After that, another change was made to system mode settings. It had been set by installers to charge to 80% and discharge to 20%. This was changed to charge to 100% and discharge to 25%, on the basis that the batteries will never recalibate and balance until the BMS sees 100% SOC. All seemed well for a few days, except our off-peak periods were not long enough to ever get above 98% SOC, so I elevated the previous discharge to a 27% setting and stretched the next charge period by half an hour of peak electricity, to try to get to 100%. Later, ours plateaued to 62% SOC and has been stuck at 62% for over a week and not charging or discharging. Master battery shows 3 solid green LEDs, both slavesshow 4 solid green LEDs, and Sunsynk say more than a 2v dc difference between battery voltage and BMS voltage will stop system from charging. Their latest interest is in the DC breaker between master battery and inverter. Ours is a GIVENERGY PEBS-L 100a. Sunsynk have said these can be a problem and suggest a different make and model. They suggested I use that breaker to power off and back on "according to installers instructions". I have relayed this to installers and await their "installers instructions". If this does not cure things, then they suggest replacing the breaker.