Plug in balcony solar UK , just a Lidl question

[ericmark]

when the switch contacts are changing

That I suppose it the point, with the generators I put online, it was a physical switch, so needed to be synced only just before I throw the switch.

So with a UPS the supply has to be in sync with the mains, so at any time the connection can be made or broken.

I see where it is part inverter and part mains, there must be a possibility that there is some reverse flow, but I don't know how the battery packs work, with some battery packs the inverter is rated well over the rating of the battery, as one can up the output by adding more batteries.

So I have to admit not sure how exactly the battery packs work, I know the pack plugs into the mains, and it supplies an output to its built in sockets, and it is classed as an EPS supply, and EPS differs from UPS due to switching time. But exactly how it works I don't know.

They have however been sold in the UK for many years now, and do allow mains and solar to supply items, I looked at one, and came to the conclusion to use on mains and solar, I would need a time switch, to turn on mains 00:30 to 05:30 and then turn the mains off, so it would have discharged enough to use the solar during the day. But each model seems to vary, so not 100% sure if they can allow a back feed in some cases, even if that back feed is not intentional.

 

[JohnW2]

That I suppose it the point, with the generators I put online, it was a physical switch, so needed to be synced only just before I throw the switch.

If it is a physical break-before-make switch, then there is no need for 'synch' at any point in time,

I would imagine that one can probably make electronic break-before-make switching almost as 'foolproof' as mechanical switching - and, indeed, I suppose that the electronics could actually feed an electromechanical b-b-m contactor/relay.

So with a UPS the supply has to be in sync with the mains, so at any time the connection can be made or broken.

That depends upon what you mean by a "UPS", of which there are several variants. With the small ones that I've used, the load is never powered directly from 'the mains', so there is no need for anything to be 'synched' with anything else .... the load is powered by a battery-powered inverter, and that battery is kept charged up by 'the mains', when present.

 

[bernardgreen]

A UPS ( Un-interruptable Power Supply ) suppies the load continuiusly with an AC supply produced by an invertor in the UPS. The invertor is fed from a DC supply from a battery that is float charged from the grid supply. If the grid fails then the invertor continues to provide AC power to the load without any interruption.

When a an SPS ( Standby Power Supply ) detects grid failure it will power up it's invertor and switch the load from grid to invertor when the invertor has stabiilised

 

[JohnW2]

A UPS ( Un-interruptable Power Supply ) suppies the load continuiusly with an AC supply produced by an invertor in the UPS. The invertor is fed from a DC supply from a battery that is float charged from the grid supply. If the grid fails then the invertor continues to provide AC power to the load without any interruption.

Quite so. As I wrote, that's exactly what all the UPSs I have, and have ever had, have done - so there is no question of them needing to be 'grid tied'

 

[ebee]

If it is a physical break-before-make switch, then there is no need for 'synch' at any point in time,

Even so, old habits etc etc and best being on the safe side unneededly than risk forgeting then dash! Belts/braces or/both kind of habit.

 

[JohnW2]

Even so, old habits etc etc and best being on the safe side unneededly than risk forgeting then dash! Belts/braces or/both kind of habit.

I really don't think that's applicable in relation to what I'm saying. If there is essentially no way in which the grid supply and a locally-generated one (PV, genny, batter+inverter, PV or whatever) can 'become connected', it really makes little sense (at least, to me) to worry about whether the two are 'synched'.

 

[ericmark]

efixx have done another video

claiming that bidirectional RCDs/RCBOs are not required for plug in solar.

Not sure if I agree, but neither can I show their claims are wrong, it talks about tiny signature to tell other inverters that is in an island, which seems great, but it would need some standard so that all inverters use the same system, so until a standard is published we can't know if any inverter complies with what at the moment is an unpublished standard.

By September the solar panel output is reducing, last year May was the best month, in 2024 it was June, so May last year I got 900 kWh by September 500 kWh and the 10th, 11th, and 12th months were dropping 250 to 125 kWh, and it did not raise by any significant amount until March. This is with 6 kW of panels.

So we are running out of time for any announcement, by the end of this month, it will be too late for manufacturers to produce units to comply with any new standard and get them into the shops before the season is over.

 

[ericmark]

And yet another one

it does not say anything new, so why.

Problems are still the same, will a reverse power shut off fast enough to stop damage, and two not all units with in/out marked are uni-direction and third how do you know if marked in/out without removing the CU cover.

 

[SUNRAY]

A UPS ( Un-interruptable Power Supply ) suppies the load continuiusly with an AC supply produced by an invertor in the UPS. The invertor is fed from a DC supply from a battery that is float charged from the grid supply. If the grid fails then the invertor continues to provide AC power to the load without any interruption.

When a an SPS ( Standby Power Supply ) detects grid failure it will power up it's invertor and switch the load from grid to invertor when the invertor has stabiilised

I think you'll find that's not always the case. I used to have an expensive 1KW UPS which ran on 24V (2*12V 38AH internal batteries) I primarily used it to keep 95AH batteries charged (Multiple pairs simultaneously) which it did very well and included an in-line 8A MI meter (Left over from previous charging system) so I had visible indication of what was happening. Plugging a Henry Hoover load into the UPS made no difference but creating mains fail instantly showed a massive overload of the meter. I'm not convinced the sysstem would be so perfectly built that not the slightest of flicker could be seen on the undamped meter.

 

[bernardgreen]

I think you'll find that's not always the case.

The difference between UPS and SPS has changed over time.

An SPS becomes active and takes over the load when mains failure is detected, This can mean the load has no supply for a few seconds. This is acceptable when the load can tolerate the interruption.

A UPS is necessary when the load cannot tolerate any transient change of mains phase angle.

 

[ericmark]

Yes, my power to freezers is classed as an EPS, not an UPS, and it seems the difference is the milliseconds it takes to change over.

But the UPS units I have worked with, do not run all through the inverter all the time, but take over when the supply drops, and they stay synchronised to the mains supply, so the change over can be rapid. But they don't back feed.

 

[JohnW2]

But the UPS units I have worked with, do not run all through the inverter all the time, but take over when the supply drops, and they stay synchronised to the mains supply ...

If the mains supply 'drops' (fails) there is obviously then no mains supply to which an inverter could be synchronised, even if it would like to be

 

[ericmark]

Exactly, so it needs to be in sync before the power outage to be sure no problem when changing over due to back EMF from motors etc, and also with return it needs to sync before letting the grid supply take over again.

With no sync-scope, I was told to wait 5 minutes for all the ACs to lose pressure before reconnecting the supply. I know my portable AC runs for around 5 minutes before the compressor starts. So either less than 20 mS or at least 3 minutes.

 

[JohnW2]

Exactly, so it needs to be in sync before the power outage to be sure no problem when changing over due to back EMF from motors etc, and also with return it needs to sync before letting the grid supply take over again.

I suspect that you are, again, drifting well away from anything relevant to a domestic electrical installation or domestic electrical equipment/appliances.

 

[ericmark]

I suspect that you are, again, drifting well away from anything relevant to a domestic electrical installation

Today be it industrial or domestic, loads of motors are driven by inverters, I know my washing machine, fridge/freezer and freezer are inverter drives, and it would not matter if the change over is out of sync. But we still do have some single phase motors, and when I was talking about changing over generators, these were supplying an accommodation block, with loads of ACs to keep the rooms cool. If it had not had so many refrigeration units, or if they were inverter drives, it would not have mattered so much.

I have two with inverter drive and two with the old capacitor start, I am not aware of any delay built into the old capacitor start units, I think they would likely stall, and then it would take time for the overload to re-energise and then start with no load.

As to change over in 40 mS rather than 20 mS, yes likely the refrigeration units would not stop. And I know my AC, once powered down, it takes around 5 minutes to restart the compressor, clearly some delay built in.

As to a PC, how many mS the capacitors in the switch mode power supply would last I really don't know, and a stop watch would not be good enough to find out. All I can do is google the difference between UPS and EPS

A UPS (Uninterruptible Power Supply) focuses on protecting sensitive IT equipment and preventing data loss by providing continuous, clean power and instant switching. An EPS (Emergency Power System) focuses on life safety and preventing disasters by supplying heavy-duty, long-lasting backup power for infrastructure like emergency lighting and fire pumps.

Ask difference between UPS and EPS and SPS and

While all three provide backup power, they serve different primary purposes and react to outages at different speeds. A UPS provides instantaneous power for sensitive electronics, an EPS protects life-safety systems with a slight delay, and SPS (depending on the context) refers to either a broad Solar Power Station or a specific type of Solar/Smart Power Supply inverter.

It seems SPS can be as fast as UPS.