LuxPower - emergency backup enabling

[Stinsy]

The problem is that if the solar inverter is producing more than the house load and the battery is full the LUX has to be able to tell the PV inverter to throttle back. If it can't then you have problems. I don't believe it has that facility and can't accept power in on the output..

You may be able to do it but would have to have automatic loads come on.

The solar is curtailed in this situation. I have this occur on my Lux inverter because I have 5kWp of panels so on sunny days the battery can become full and the inverter is limited to 3.6kW (you can set it to a different figure or limit export if you like which curtails the solar further).

[Kommando]

On grid that works with G98/G99 where your export limit is 3.68kw, ie the grid is an extra battery but if you have gone off grid and islanding then your inverter needs to only make what the load is on the house and no more once the battery is full and the sun is out. In my case my Battery Inverter Sunny Island raises the frequency over 50htz in a controlled manner and the SMA Sunny Boy inverters throttle back their output even to the point of nil by 52htz. This is a special off grid mode in the SMA settings so that Sunny Boys can be used off grid with a Sunny Island. I have tweaked it by using a Pi to monitor the frequency and turn loads on and off to keep the inverter output up but if that was to fail the SB's would revert to full SMA control by the SI. So how does the Luxpower handle this when off grid.

[Stinsy]

On grid that works with G98/G99 where your export limit is 3.68kw, ie the grid is an extra battery but if you have gone off grid and islanding then your inverter needs to only make what the load is on the house and no more once the battery is full and the sun is out. In my case my Battery Inverter Sunny Island raises the frequency over 50htz in a controlled manner and the SMA Sunny Boy inverters throttle back their output even to the point of nil by 52htz. This is a special off grid mode in the SMA settings so that Sunny Boys can be used off grid with a Sunny Island. I have tweaked it by using a Pi to monitor the frequency and turn loads on and off to keep the inverter output up but if that was to fail the SB's would revert to full SMA control by the SI. So how does the Luxpower handle this when off grid.

Because it is all in one box there is no need to communicate by changing the frequency.

[Tinbum]

The problem is that if the solar inverter is producing more than the house load and the battery is full the LUX has to be able to tell the PV inverter to throttle back. If it can't then you have problems. I don't believe it has that facility and can't accept power in on the output..

You may be able to do it but would have to have automatic loads come on.

The solar is curtailed in this situation. I have this occur on my Lux inverter because I have 5kWp of panels so on sunny days the battery can become full and the inverter is limited to 3.6kW (you can set it to a different figure or limit export if you like which curtails the solar further).

How- it's not controlling the growatt inverter?

[Tinbum]

On grid that works with G98/G99 where your export limit is 3.68kw, ie the grid is an extra battery but if you have gone off grid and islanding then your inverter needs to only make what the load is on the house and no more once the battery is full and the sun is out. In my case my Battery Inverter Sunny Island raises the frequency over 50htz in a controlled manner and the SMA Sunny Boy inverters throttle back their output even to the point of nil by 52htz. This is a special off grid mode in the SMA settings so that Sunny Boys can be used off grid with a Sunny Island. I have tweaked it by using a Pi to monitor the frequency and turn loads on and off to keep the inverter output up but if that was to fail the SB's would revert to full SMA control by the SI. So how does the Luxpower handle this when off grid.

Because it is all in one box there is no need to communicate by changing the frequency.

It's two boxes, a Growatt and a LUX so they need to communicate as Kommando says.

[stevevoller]

So am I basically screwed with what I have? (Growatt min 6000 with PV + Luxpower ACS 3600 with batteries)

In an extended power-cut I can run the UPS load until the battery expires and then everything is off.

Is there a solution that will let me keep the batteries, PV and preferably the inverters, or do I need a different solution to work in an extended power cut?

[Joeboy]

So am I basically screwed with what I have? (Growatt min 6000 with PV + Luxpower ACS 3600 with batteries)

In an extended power-cut I can run the UPS load until the battery expires and then everything is off.

Is there a solution that will let me keep the batteries, PV and preferably the inverters, or do I need a different solution to work in an extended power cut?

Steve,
My solution to grid loss and keeping access to the DC power in the batteries is a DC to AC inverter with 3 pin plug built in, T'd off of the battery stack. Its not particularly fancy or expensive and it is simple although i am restricted to an extension reel to where i need the power. I also have the benefit of half the PV running through a charge controller directly to the batteries rather than through a grid tied inverter. The result is an offgrid reliable 2kW supply that can spike to 3kW for short moments fed from 5kWp.

Something like this.
https://www.amazon.co.uk/FENGSSLL-Effic ... 02&sr=8-18

Basic though this solution is I can cook, heat my HWT, run PC, TV, lights etc if the grid fails. Although not all at once! I have run the washing machine on the inverter as a test, no problem. I could also charge the EV through the granny charger. My point being that for not too much outlay a reasonable facsimile of normal life can take place in extended power outages. Preferably in the March to Sept window.

[stevevoller]

With that small inverter would I need to disconnect the PV from the Growatt inverter and then connect it to that small inverter and then take the AC from it on an extension lead to use in the house to try and reduce the load on the batteries ?

But would not be able to charge the main batteries in any way.

(Are the input connectors for that small inverter standard, or am I hoping for too much that manufacturers have the same connectors?)

As an idea though is it possible to have a second inverter (off grid) that can be connected with a transfer switch to run during extended power cuts?
Short Power cuts , key things can be on the UPS output on the Luxpower.


Is this possible?
So switch the breaker on the grid to to isolate the house
Use the isolator on the PV to temporarily disconnect the PV.
Use a transfer switch to swap the PV in to a "parallel" off-grid PV inverter and another transfer switch to switch to change the connection from the consumer unit to the new off grid inverter instead of the Growatt?

[nowty]

If you want to be more power cut resilient your choices are,

1) Use the UPS on the Lux you have and DC Couple some solar via charge controllers to the DC battery side, thats what Joeboy partly uses as his grid tie solar will still trip out. DC coupling will still work in a power cut, you can even re-wire stuff to do this in an extended power cut situation. Most charge controllers don't like high voltages so you could parallel up some of your solar to be compatible with them.

2) Change your hardware to a single large On/Off grid hybrid inverter which takes both solar and batts, thats what Stinsy was on about. That is effectively an OffGrid capable inverter with DC coupling built in as in (1) above.

3) As Tinbum says you can do it with controlled loads but its complicated.

4) Change your hardware to SMA gear like Kommando and myself have and you can have what you want for a price !

[Joeboy]

With that small inverter would I need to disconnect the PV from the Growatt inverter and then connect it to that small inverter and then take the AC from it on an extension lead to use in the house to try and reduce the load on the batteries ?

But would not be able to charge the main batteries in any way.

(Are the input connectors for that small inverter standard, or am I hoping for too much that manufacturers have the same connectors?)

As an idea though is it possible to have a second inverter (off grid) that can be connected with a transfer switch to run during extended power cuts?
Short Power cuts , key things can be on the UPS output on the Luxpower.


Is this possible?
So switch the breaker on the grid to to isolate the house
Use the isolator on the PV to temporarily disconnect the PV.
Use a transfer switch to swap the PV in to a "parallel" off-grid PV inverter and another transfer switch to switch to change the connection from the consumer unit to the new off grid inverter instead of the Growatt?

I assume all your PV runs through grid tied inverter? Can't offer a solution for that but can say that a small inverter as linked will make a simple solution. The connections on the inverter are generally threaded posts so you'd need to make up cables to connect to your growatt unit. It's not that hard to do. Supply photos and I'm sure we can help if it's new to you.

As to change over switches etc, I didn't go down that route as I like as simple as possible. I am sure someone will be along who can help there. All I do is flick a switch to turn the offgrid inverter on and plug in a 230vac reel.

The added benefit is that my family know this and its easy. I have some other 12vdc lighting ran in to the garage so nobody has to stumble about in the dark. You can really make it however you wish but worth keeping an eye on the likelihood/cost financial balance.

Personally I'd add some more panels running through a charge controller. That way you create an offgrid back up system that operates in normal conditions anyway but does its offgrid thing when you need it to without touching a single thing.