Inverter setting to cope with a power cut

[MrTWales]

Hi - I wonder if I can ask about this. I have had panels set up for only a few days and yesterday the area had a power cut. This impacted my house as any other, but I want to make sure that I understand what options I have. 

 

Based on a quick search it seems like inverters turn off the solar generation is there is a power cut, so that no current flows out as this may impact on recovery work, but it is likely possible to run on the battery? This would help during the odd random outage but moreso if there is ever a time when power is cut at night (as has been mooted as a possibility).

 

My router is a 6K Luxpower system and I can see a setting via a browser called "Power Backup", which can be enabled or disabled. It sounds like - assuming that this is safe - this would have to be set to "Enable"? The manual sort of suggests this but doesn't give any detail. I have tried to toggle, just to see what happens and one thing that happens is that - according to the graphic - once I set to "Enable" the battery isn't actually used. Eg now the battery has some decent charge but all comes from the grid unless I change this back, though I can click an option to force a discharge. So, I'm confused on how this should be set up! I note that the app has two extra options below this toggle for "Feed-in Grid" and "Feed in Grid Power Percent" so maybe I want those to be zero?

 

One other thing I've noticed is that there is a tiny draw from the grid, even when in theory there shouldn't, and also a tiny feed into the grid, when in theory there shouldn't. I think that this may be just the way this kind of system works? The only connection between the inverter and the meter box is an ethernet cable, that wraps around one of the main cable and I think it detects the magnetism change (or something) so if there is a draw from the grid then it triggers and then the battery is used if there is enough charge. This may be totally wrong but even though the amounts are small it would be nice to reduce them if there is an easy setting option. (I will shortly get a diverter to the immersion heater fitted - they ran out of time on the day - so maybe this helps any feed in to the grid but maybe not if there is always this short change over period?)

[Pocster]

36 minutes ago, MrTWales said:

One other thing I've noticed is that there is a tiny draw from the grid, even when in theory there shouldn't, and also a tiny feed into the grid, when in theory there shouldn't. I think that this may be just the way this kind of system works?

Yes . It’s ‘ checking ‘ the grid is there and adjusts to suit ; perfectly normal .

[Temp]

This really isn't something you should mess with. Get your installer involved.

[MrTWales]

18 hours ago, pocster said:

Yes . It’s ‘ checking ‘ the grid is there and adjusts to suit ; perfectly normal .

 

Thanks - it looks like I'm importing around 0.1kW per day at the moment (with the battery never getting full) - is this amount normal?

[MrTWales]

18 hours ago, Temp said:

This really isn't something you should mess with. Get your installer involved.

Yes sure I will ask but I want to understand how it works if I can.

[Pocster]

1 minute ago, MrTWales said:

 

Thanks - it looks like I'm importing around 0.1kW per day at the moment (with the battery never getting full) - is this amount normal?

Yeah that sounds similar to mine. Also if there's a big change the inverter can't 'swap' quick enough so you can see a large amount taken from the grid ( maybe a few Kw ) but just for a few seconds.

[MrTWales]

6 minutes ago, pocster said:

Yeah that sounds similar to mine. Also if there's a big change the inverter can't 'swap' quick enough so you can see a large amount taken from the grid ( maybe a few Kw ) but just for a few seconds.

 

Thanks. It's no big deal but I just wanted to make sure that there wasn't a setting that could be tweaked. It does make me feel sad though when the diagram thing shows the generation going to the house, to the battery and to the grid at the same time!

[SteamyTea]

9 minutes ago, MrTWales said:

it looks like I'm importing around 0.1kW per day at the moment (with the battery never getting full) - is this amount normal?

Normal for power, it is what I drew, on average, from the grid last week.

It will be 2.4 kWh/day, so at 35p/kWh, 84p/day, before everything else is added.

[MrTWales]

2 minutes ago, SteamyTea said:

Normal for power, it is what I drew, on average, from the grid last week.

It will be 2.4 kWh/day, so at 35p/kWh, 84p/day, before everything else is added.

Oh sorry my post had a typo. I'm importing a fair amount and maybe it is something like 0.1kW that in theory shouldn't be imorted (eg when the battery has charge of the generation is enough). I meant to say 0.1kW per day of export (not import). I get that it may take a while to trigger the battery when the grid is suddenly used but I didn't expect any to be exported when the battery will never get to be full at this time of year.

[Pocster]

8 minutes ago, MrTWales said:

 

Thanks. It's no big deal but I just wanted to make sure that there wasn't a setting that could be tweaked. It does make me feel sad though when the diagram thing shows the generation going to the house, to the battery and to the grid at the same time!

Lol . Same as me . Just seeing that bit go to or from the grid bugs me .

[Carrerahill]

20 hours ago, MrTWales said:

Hi - I wonder if I can ask about this. I have had panels set up for only a few days and yesterday the area had a power cut. This impacted my house as any other, but I want to make sure that I understand what options I have. 

 

Based on a quick search it seems like inverters turn off the solar generation is there is a power cut, so that no current flows out as this may impact on recovery work, but it is likely possible to run on the battery? This would help during the odd random outage but moreso if there is ever a time when power is cut at night (as has been mooted as a possibility).

 

My router is a 6K Luxpower system and I can see a setting via a browser called "Power Backup", which can be enabled or disabled. It sounds like - assuming that this is safe - this would have to be set to "Enable"? The manual sort of suggests this but doesn't give any detail. I have tried to toggle, just to see what happens and one thing that happens is that - according to the graphic - once I set to "Enable" the battery isn't actually used. Eg now the battery has some decent charge but all comes from the grid unless I change this back, though I can click an option to force a discharge. So, I'm confused on how this should be set up! I note that the app has two extra options below this toggle for "Feed-in Grid" and "Feed in Grid Power Percent" so maybe I want those to be zero?

 

One other thing I've noticed is that there is a tiny draw from the grid, even when in theory there shouldn't, and also a tiny feed into the grid, when in theory there shouldn't. I think that this may be just the way this kind of system works? The only connection between the inverter and the meter box is an ethernet cable, that wraps around one of the main cable and I think it detects the magnetism change (or something) so if there is a draw from the grid then it triggers and then the battery is used if there is enough charge. This may be totally wrong but even though the amounts are small it would be nice to reduce them if there is an easy setting option. (I will shortly get a diverter to the immersion heater fitted - they ran out of time on the day - so maybe this helps any feed in to the grid but maybe not if there is always this short change over period?)

Is the Luxpower a hybrid islanding inverter? 

 

If you set your inverter to some sort of "backup" mode (which I would be interested to know just exactly what it does in this mode) then with the power out, your inverter would be back feeding your house and the rest of the local grid, so it would need to sit between the grid and the house to work. If not, then It would fall flat because your inverter would also be trying to pickup the load of anyone else connected to the same, isolated due to power cut, grid infrastructure as you. That could be a whole village or street in a city.

 

If your inverter just connects to your consumer unit via one of the outgoing MCB's then it cannot work as a hybrid, well at least not safely. 

 

How inverters that can allow this off grid operation work is that they have an AC output, and an AC input, on failure of the AC input it still allows the output to work via solar and usually stored power in batteries. But this is designed so that none of the locally generated power can be sent out onto the grid and zap a linesman.

 

All grid-tied inverters sold in the UK must shutdown immediately after they lose grid connection - within about 0.02s which is 1 cycle enough for it to monitor the dropout in one cycle of the AC. 

 

It is possible to create a reference voltage within your house when isolated from the grid, to get the inverter to work, I know someone who does this with a generator. He kills the main isolator into his house, fires up a diesel generator which runs his essentials, but it also allows his inverter to restart and the PV and generator will run the house. 

 

Edited October 31, 2022 by Carrerahill

[MrTWales]

18 minutes ago, Carrerahill said:

Is the Luxpower a hybrid islanding inverter? 

 

If you set your inverter to some sort of "backup" mode (which I would be interested to know just exactly what it does in this mode) then with the power out, your inverter would be back feeding your house and the rest of the local grid, so it would need to sit between the grid and the house to work. If not, then It would fall flat because your inverter would also be trying to pickup the load of anyone else connected to the same, isolated due to power cut, grid infrastructure as you. That could be a whole village or street in a city.

 

If your inverter just connects to your consumer unit via one of the outgoing MCB's then it cannot work as a hybrid, well at least not safely. 

 

How inverters that can allow this off grid operation work is that they have an AC output, and an AC input, on failure of the AC input it still allows the output to work via solar and usually stored power in batteries. But this is designed so that none of the locally generated power can be sent out onto the grid and zap a linesman.

 

All grid-tied inverters sold in the UK must shutdown immediately after they lose grid connection - within about 0.02s which is 1 cycle enough for it to monitor the dropout in one cycle of the AC. 

 

It is possible to create a reference voltage within your house when isolated from the grid, to get the inverter to work, I know someone who does this with a generator. He kills the main isolator into his house, fires up a diesel generator which runs his essentials, but it also allows his inverter to restart and the PV and generator will run the house. 

 

Thanks, that's very useful. Everytime I read something like this I realise that I really have almost no real understanding of how these systems work.

 

The manual just says "LXP Hybrid Inverter". The set up is unusual, maybe, as the battery and inverter sit in a garden build which is connected to the meter by a cable through to it's own little box in the meter box. There is this little box and other that says "House".

 

I'll have to ask the installer but I'm not too confident now 😞