@dmajwool I’m advised that in my case, I can’t use a negative value since my grid company doesn’t allow export at all. They don’t penalize me or even monitor for any exports. A little feed in is fine by me but I’m not sure what it does to a worker maintaining the grid. For the sake of the workers and to maintain the integrity of the grid, I want to now run off-grid as much as feasible.
I don’t think that danger to the linesmen would arise : the feed-in would stop as soon as the grid connection was cut.
Nothing. Anti-Islanding safety is given by the grid code in combination with an MP2/Quattro2 (or by using an external inti-islanding relay in case of MP1/Quattro1), not by the power you are regularly feeding back.
That’s reassuring.
Under the grid code, each system has LOM detection enabled - this is a requirement for certification.
The older units and most quattros only have a single input relay, so technically one could fail closed and be a safety risk, hence the need for an external contactor with dual relays.
The MP2’s and Q2’s etc all have dual input relays so that cannot happen.
The multiple clicks you hear on grid recovery is all the relay testing happening. The system will fail to offline if any relay fails.
I’m using some sort of external relay though I don’t trust it fully. I plan to replace ít with the recommended one later. It’s not locally available. I had to make a special order to import it.
I myself used multiplus without ESS assistant and controlled ignore grid signal via nodered depending on soc and load. When overloaded I allowed to take grid power with shore limit set in a way that max power was taken from multiplus. When low soc I also stopped ignoring grid so that multiplus switches to bypass. This approach has one advantage - nice clean and stable 230v in inverter mode, but also one huge drawback - no grid feed-in. I have a possibility to take some of energy fed back to grid back for free when needed. In winter this is very important as there is very little solar power during that season. If this is not your concern, this might work just fine for you. More battery would even better optimize your setup as with 14kWp on a sunny day batteries get immediately full and you are practicaly wasting energy that later you need to buy from grid… good managed ESS might be a better solution for you, especially to shift power between seasons. Get friends with nodered…
@BartVic I see what you mean about the drawback of not exporting to grid, but the OP has specifically ruled out that possibility.
We are indeed fortunate that we can use the grid like an “interseasonal battery” exporting in summer and importing in winter.
If feed in is strictly prohibited there is also a possibility to make pure island installation with no connection to grid and no ESS (ESS means grid parallel) and add one more multiplus or even a simple 48v charger to simply charge the 48v battery from grid when there is too low SoC. In such setup your circuits stay 100% isolated from grid while having an option to charge battery if not enough sun. Such charging can be from grid or even genset and your voltage will stay stable. Without ESS such working setup is also possible but in order to charge from grid the unit will have to close relay connecting your loads with grid as the inverter is being used either to convert dc to ac OR to convert ac to dc for the charging function. That more or less are your options. And yes, if feed in is prohibited ESS is not really an option for you.
Sorry but that is way off the mark.
ESS means battery storage and self-consumption using PV.
It has many different capabilities, more when you consider customisation.
Exporting power is only one feature and many ESS systems are in use to manage solar and battery consumption while never feeding back.
Grid parallel is just another architecture, favoured in European regions due to the ease of wiring. There are also many, many systems with all loads on AC OUT, treated as critical loads, especially in poor grid areas or where any form of outage is undesired.
You can use ESS pretty much anywhere, the reason off-grid is not encouraged, is the interaction between ESS and generators and the chance of having shore connections being live, momentarily.
ESS works brilliantly in AC-ignore configurations, where an installation conditionally connects to grid to deal with shortfalls.