4.6 kW Goodwe with backed up and non-backed up circuits.
Now, this morning the grid is on, the sun is shining, demand is currently 3.17 kW and everything sails along nicely. The bulk of that demand is on the non-backed up circuits.
When does the 4.6 kW limit kick in? Does that apply to total load, or to demand on the backed up circuits?
My guess is that it’s total load, and when the grid goes down then the inverter sheds the non-backed up circuits which will reduce the load.
Which means I can only ever draw 4.6 kW in my house. Which means the guest geyser (which I am testing today) is only useable as long as nobody wants to use the kettle or the microwave.
20A on the backup side. The non-essentials don’t go through the inverter, so they are unlimited. (But the inverter can only assist them up to 4600W for the total backup+non-essential)
If your panels can max out the inverter, and your non-backup side goes lets say up to 10kW. The inverter will send as much as it can to the non-backup side.
eg.
Panels can max out the 4.6kW on panels, backup use lets say 1kW, and non-backup is at 10kW, so total should be 11kW. The inverter will send 1kW to backup and 3.6kW to non-backup, and the non-backup will then get the remaining 6.4kW from the grid.
Nothing will be sent to battery for charging, theoretically, because the load is taking up all the generation. However, in practice, the mppt can generate a bit more than 4.6kW. 4.6kW is the invertion limit. Then a bit more can be used from panels to do some battery charging. So it is not uncommon to see panel/generation going over 4.6kW. I have personally seen it go just over 5.5kW if there is max invertion used and battery can take a charge.
Yes, the MPPTs can go up to 6.4kW. In that case only 4.6kW can go to AC, the rest will go to the battery (if it can take charge). But it can only do that if the backup+non-essentials use less than 4.6kW. If the total load goes over 4.6kW, it won’t charge the battery and will again cap at 4.6kW.
Not really (it’s the geyser that gets it from the grid)
A better way of thinking about it is that everything on the non-essential side is only connected to the grid. What the inverter does is to export all the excess it has. This offsets what is used from the grid. It can do this because it knows what you are using from the grid because there is a CT to measure.
In your case it’s slightly different because you can export, so the inverter will always export all the excess (up to the limit if there is a limit set). But when solar is unavailable it will export from the battery to try and match your use on non-essentials.
Without reading this in too much detail, the inverters most commonly used by people here are grid-interactive. While connected to the grid, all loads (whether on the input or output) essentially run from grid power, and the inverter itself acts like a grid-tied PV-inverter which just offsets the load by as much as it can, using either solar or battery. If you have more loads, nothing trips, nothing switches off… the remainder just comes from the grid.
If the grid fails, then the picture changes. If the output loads exceed the maximum capacity, it overloads and switches off.
Most of that is true, but the backup side is connected to the grid via a relay or something else that would have a limit too. So I dont think the backup side can use unlimited amounts of power even while connected to the grid.
Pretty certain, my goodwe es 4.6kW inverter reboot (basically trip the backup side) if the backup side exceed 4.6kW for longer than 10 seconds, regardless of whether the grid is available or not.
True. In my experience this relay is sized larger than the inverter though, so that for many people it will translate into “as much as you want as long as the grid is up”. For the most popular Victron unit (the 5kVA), the transfer switch is 50A, and most single-phase houses have a 63A breaker. That’s close enough
I would expect it to only report such overload warnings when the grid is disconnected. Perhaps there should be a severity level below “warning”, under which such notifications should fall.
Mine doesn’t do this exactly. It is possible to trip the inverter whilst we have grid power (indeed, if a trip were to occur during load shedding and when there’s no PV, then we would have problems because there would be no way for the inverter to restart itself).
So, it’s nice sunny morning, grid is up but if the total backed up loads go over 20A, the system will trip (and then reset itelf). This requires people to turn on lots of things in the kitchen. It does still happen occasionally.
A recent test was to turn on the guest geyser (not backed up) on a nice sunny day when I knew that there were going to no appliances in use bar occasional use of the kettle. The grid was up, otherwise I could not have done the test. The total load got high. This includes the guest geyser and the pool pump which are not backed up. At one time, for about 20 minutes, the system was running very close to the 20A limit. But a good chunk of that was not backed up - guest geyser (2kW) and pool up (about 800W). During that 20 minute peak I made a cup of coffee, so TOTAL load would have exceeded 20A at that time
Nothing tripped. So the non-backed up loads do not contribute (if that’s the right word) to the 20A limit on the inverter.
But what puzzles me is that during that 20 minute spell the load exceeded PV, but the inverter did not draw from the grid, it used the battery. So now that means inversion, and now the non-backed up loads are counting towards the inverter limit. When I turned the kettle on, as already stated, total load (and the demand on the inverter) would have exceeded 20A surely?
Or… the Goodwe SEMS portal only shows data at 5 minute intervals. The increase in load caused by the kettle is not shown on the graph, I presume it fell between the two intervals. Could it be that there was a brief draw from the grid as well, also falling neatly between the two intervals?
It seems that certainly with my system the backed up loads are ring fenced and are always being fed via inversion. So if you exceed 20A on those loads then the inverter will always trip. Irrespective of grid presence and irrespective of the amount of PV available. Always. Every time.
Hmmm… I would be interested to know if your inverter is on the CoCT list of approved inverters. Their reason for the inverters they have given the nod to are grid tie as described by Plonk. These will give little trouble for the user (and consequently for the utility) since they don’t trip…
If there’s anything I have gathered from CoCTs list it is this point!
It is on the list. If it trips because it’s overloaded it won’t cause them any trouble. My connection to the grid stays up, it is the inverter that trips.
Nope. While the inverter will try to power the non-backed up circuit, it will go to the limit but not over and trip. It essentially will use what is available between PV 1st, battery 2nd, and grid is always the lowest priority, even for the non-backed up circuit.
Another point here, this inverter is actually lazy, to be safe for itself. When I turn on my kettle, which is on the backed up side, that initial demand spike, is off-loaded on to the grid. The inverter then slowly move that load over to PV or battery. PV can be pretty quick if the battery was busy charging, but if the PV available is less than the new demand, the inverter really slowly move demand to the battery. I suspect this has something to do with the BMS on the batteries I have that also protect themself. I see this happen with both charging and discharging, where it essentially ramps up the charge/discharge rate. Anyways, you can see this, if you use something better than SEMS (see point below).
SEMS portal is totally useless for real time details. I’ve set my home assistant to get an update every 5 seconds. Gives you far better idea what is going on.
Not true. See my top most point in this post. This inverter send spikes in demand to the grid when the grid is available. I suspect, this type of behaviour should allow the inverter to last a bit longer.
Something else about the Goodwe 5048ES. While it is rated at 4.6kW, it can spike up to 6.7kW for 10 seconds (per documentation).
It only trips after 10 seconds if the load is above 4.6kW.
So my Home Assistant, since it gets updates every 5 seconds, I have set up an automation that can drop certain loads when this happen. Has reduced our annoyance trips by 99%. Things like a kettle, can wait temporarily if something else is turned on, like the microwave, or the dishwasher happens to spike at that time, or the washing machine etc.
It definitely was on the list, at the time of installation for me. Sadly, my install happened before the now popular Sunsynk inverters were added to the list, that was 2019/2020 list. I remember the Sunsynks got on to the list around end 2020 beginning 2021.
I do know that inverters also get removed from this list from time to time, so it might have been removed after my installed was signed off, but I remember checking 2022/2023 list and it was still on there. No idea if there is a newer list now.
It is certainly on whatever list COJ uses. My system is registered with the City, and the engineer who did the registration for me did all the required checks, including whether or not the inverter is on the approved list.
