JayMardern

This has been working great thank you - you're right, it was just auth, the rest stayed as-is. I honestly don't mind the cloud reliance as long as it's reliable (it actually has been for the last few months after their infrastructure move) and it doesn't change (like it did in this case). My understanding is that the revised auth process was to improve security - which is fine but only if we know in advance it's coming.

Looks like the whole SunSynk API is down? Authentication no longer succeeding across the board. Any official announcements?

At night we simulate powering-essentials-only-from-battery by specifying 700w (our average essentials load amount) in the time-of-use 'Power' column. That slot also has a 50% SOC target: so at night, the battery is allowed to slowly discharge down to 50%, with a maximum draw of 700w. If a geyser (or other high-power item) gets powered on at night, the balance above 700w simply comes from the grid. This achieves what @Sidewinder mentions above in terms of allowing us to gradually drop down to a battery SOC 'checkpoint' so that there's always left-over-battery for an unexpected outage. (The next slot - until just before sunrise - is set to 30%, again with a 700w battery limit). This also ensures that we consume most of the energy in the battery (which hopefully came from sunshine the day before) - and also makes battery capacity available for spare sunshine the next day; whilst also going easier on the battery (low-ish current drawn over a longer time).

Yeah you can: battery charging doesn't contribute to load, so indeed you can have 4kW going into the batteries while the UPS/load port draws 3kW; the total power into the inverter (from, say, grid) would be 7kW.

@Madone69 could do what we've done and put the heavy loads on the Deye/Sunsynk's Aux port, whilst specifying a minimum Aux battery SOC % - which will keep other essentials running but cut Aux loads if battery drops below the Aux threshold. You can also choose to keep Aux running (regardless of SOC) if grid is up. This protects battery SOC% whilst keeping Aux running during grid outages... saved us from cold showers when the grid's gone down, more than once!

Depends on system size, When I started with a single 5kW unit, geysers/pool pumps/stove remained on non-essentials and were back-fed with Solar by the inverter's ability to zero-export-to-CT through the grid port: this meant I didn't need to worry about the capacity constraints of the inverter since if we exceeded it's limits/production, the balance simply came from the grid. Keeping these non-essentials fed by excess PV like this was critical for return-on-investment on the system, since they're a typical home's biggest power hogs. When we parallel'ed our second unit, we then moved all these non-essentials onto the inverter's Auxiliary port (which is still constrained by the inverter's UPS/load capacity - albeit now double thanks to the second one), to let them run if there's spare battery and/or PV when the grid is down. In retrospect, with our single 5kW we could've probably swapped the one geyser's element down to 2kW and then been OK moving just that geyser to the essentials/aux, for coverage during extended grid-outages; at the cost of slower water heating due to the smaller element. The other possibility is you can put 'non-essentials' onto change-over switches to swap them between non-essentials (for most of the time when you don't want to be bothered by limits) and essentials (when the grid goes down and you need hot water!) for a best-of-both-worlds approach if you don't have tons of spare inverter capacity.

Yeah, I've spent time with hardware from both Deye (colleagues) and Sunsynk (my own) and functionality is the same on-inverter, the only difference is terminology in the menus. And colour scheme! 🙂 My installer mentioned he preferred the Sunsynk app to the Deye solution when he did the second-half of my installation last year; especially with regards to modifying settings from the SS app. Maybe this has changed since, though. Sunsynk also has a nice API which is quite clean and well documented. But indeed, if none of that matters (or you're going Home Assistant or the like) I'd just go for whatever is cheaper at the time. It's not that bad: like Bobster mentioned, 5kW goes further than you think as long as you keep cooking and heating under control. Our household ran 5kW for about a year before adding a second unit in parallel; and we had no idea when there was load shedding unless we needed the stove/oven. And while 5kW limited what high-power items could be done on the UPS side, there's of course no limit on what you do grid-side (ie, on the non-backed-up side) - so if you keep your loads under control, you can still zero-export-to-CT to your non-essentials; since both the Sunsynk and Deye models discussed here can zero-export to the grid port. So even though my geysers weren't on the UPS side, they still got mostly heated from PV when sunshine was available. And when loads exceeded 5kW, the balance just came from grid. So the cost savings were impressive - very impressive - from just the one 5kW unit, mainly thanks to zero-export-to-CT. And load shedding was a non-issue. I might've considered moving the smaller geyser onto the UPS side (with a heating element downgrade to 2kW) if I'd stuck with a single inverter. But in the end we doubled the solar-panel-count and and needed the MPPTs of a second inverter. And with the second unit, all our high-power items could go onto the inverter's Aux port since the backed-up load maximum was now 10kW.

Most welcome, This is indeed unnecessarily cycling the battery: if you need 80% in the morning then why not just swap the 65% timeslots to instead be 80% and leave it at 80%? Dropping lower (and charging afterwards) might make sense if you pay less for electricity at that time though (i.e., if you're on a time-of-use tariff). I've found that even on rainy days we can usually keep the essentials going for our setup (our essential-load during the day is ~650W - less than 10% of our PV capacity), so I leave a reserve of just 30% for morning since even rainy days typically produce more than that. Then if there's LS, the combination of whatever PV's available coupled with that 3kWh of battery storage is OK, even for a 4-hour outage.

Yeah that thread I link discusses the real-world pros and cons of each method based on members that have tried both. Aux seems to be preferred where possible since it gives a bit more control/automation; but even in my own case, if I ever wanted to add a generator I'd have to use Grid input since in my setup, Aux is in-use as an output.

You use the Aux/Gen input "peak shaving" setting to limit power from the generator on the Sunsynk. See if this helps:

I don't think this is exactly possible (stand to be corrected!) but I achieve something similar by setting the 'Power' column value for those evening timeslots equal to my average Essentials Load at night, with a lower-than-100% Batt SOC target. The inverter then limits the load on the battery to that Power value; down to that SOC. (i.e. in my setup, the 'Power' column limits battery drain, but doesn't change charging speeds). I use this to gently step the battery down overnight, powering a load roughly equal to my essentials, whilst leaving some SOC as reserve in the event of a power failure. The closer to morning (and hence sunshine) we get, the lower that timeslot's percentage is.

Note that the 5kW Sunsynk's do still have an internal fan (and it does turn on under high load/PV), but it's much quieter than the externally-vented 8kW fans. (To me, it sounds more like transformer hum than moving/'wooshing' air, pretty quiet.)

Have you checked the LiBMS info screen to verify that power is actually entering/exiting the battery? I ask because the battery bus actually doubles as a PV DC bus for parallel inverters when production is mis-matched, See if this is happening your side:

I did something similar to this. I have both of my own geysers on Aux. (Though their combined rating is still significantly lower than my inverter's: Aux is governed by the same maximum power that limits UPS/Load). My installer did change-over switches to allow us to (manually) swap them over between Aux and Non-Essential. (But in all cases, they're fed by excess PV through zero-export-to-CT). So be safe, by default I just leave the main (most frequently-used) Geyser on Aux in case of a power outage. But if it's sunny and the power is out for an extended period, we leave them both changed-over to Aux because there's no risk of them tripping the inverter if both were to turn on simultaneously. Our 'Aux On When Grid Up' setting is ticked - so Aux stays running regardless of battery SOC when the grid is up, and when the grid goes down, Aux is set to be only on above 90% to protect the SOC in case it's an extended outage. If it's load shedding we might drop this to 50% to allow us to to use the stove (also on Aux). Further to your diagram, we adopted a software approach to do this (using the standard CBI Astute timers that my electrician installed onto the geysers), to achieve round-robin' ing like you're suggesting, where if a geyser is idle (Powered On = Yes and Power Consumption = 0), then we power it off and try the next one. We only do this when the battery is close-to-full (if it's under 80%, we fail over to regular timers). Regarding Aux, think of it as an extension to UPS separated by a relay/switch. So if you want to allow the geysers to turn on only when the battery is above 80% (regardless of Grid), you'd need to set Aux On to 80%; but if you want to be able to fail over to grid, you'd need to combine this with your System Mode Timer to force the battery (from grid) to 80% if PV is insufficient; that way you can still get some geyser heating on cloudy days. So in our case, we just: Have the Aux set to be on whenever grid is up (and on at above 90% SOC when grid is down) Use timers for all our basic heating. We know that our one geyser needs 3 hours to get to full temp and the other needs 2 hours, so they're governed by CBI Astute times to switch them on and off accordingly. To boost their stored-energy capacity, we've cranked the thermostat of the one up to maximum. This means we can heat it beyond our regular requirements (essentially treating it like a battery). Then, in the event that the day is sunny and the battery hits 80%, in between these geyser timeslots, we do additional load-searching ( IF (Powered On = Yes and Power Consumption = 0) THEN Turn-Off-And-Try-Next-Geyser). Because the timers will already give us the hot water we need daily, this load-searching essentially dumps spare PV energy into the geyser which might be useful the next day if it's cloudy; or if hot-water demand is higher than expected that evening. Since we always need hot water (more important than full battery!), we leave Aux on whenever the grid is up, and the battery instead charges from whatever is left over. On a day when we can't heat our water from PV (and need to dip into grid), we usually can't get the batteries charged anyway, which is why (for us at least) waiting for a full battery before heating water didn't make sense. I feel like the most important take-away, in my experience, is that doing a Geyser round-robin only makes sense if you have spare sunshine - so like you suggest (with Aux), Battery SOC % does need to be brought into this equation. If you don't have spare sun, it's more efficient to do the 'minimum' heating your house requires via timers. Or you could perhaps measure kWh consumed by each geyser (against your average daily requirements) and use that as a cut-off when it's not sunny. (If the hardware/wiring route doesn't work out, Home Assistant might be a good software solution for both of these requirements, since it can integrate with both the inverter and your geyser timers.)

My findings were similar to yours, inverter estimate was within about ~5% of the BMS reading, for the few weeks I ran like this.