Plug in balcony solar UK , just a Lidl question

[denso13]

but I'm still a bit confused

Me too

However, perhaps what you are implying......

I never thought that you were 'implying' anything.....

 

[ericmark]

The battery box can discharge at maximum rate for battery through the socket on the front and supplement the deficit by drawing direct from the mains, so say 1 kW from battery and 1 kW from mains so a 2 kW output, and long as the output is less than 1 kW when mains is disconnected it will operate like an UPS, but since it will allow a mixture of mains and battery as it has grid tied, it can allow you to use part solar generated and part from grid.

The problem I have is the English, both types are tied to the grid, but one type back feeds the other type does not, I don't know of a phrase to differentiate between the two. They both grid tie.

As to feed into grid, as far as I am aware, my solar does not have an option to reduce its output so it does not feed into the grid, if my battery state of charge is below 100% then that will be charged first, and if my immersion heater calls for heat, that will also happen before and feed into the grid, but I have no way other than turning it off, or for the grid to be out of range, to turn the output off, at the moment 1 kW is going into the grid.

Only way not to feed into the grid is with say a 300 watts panel and a 350 watts back ground load.

 

[JohnW2]

Me too

My goodness, we do seem to have confused one another

This exchange started when you asked (in response to my statement about 'if export never occurred'):

Is that technically possible though?

... and I responded ....

It would be difficult, if not impossible, to ensure, 'technologically', that there would never be any export ....

Which, as I've said, seemed to be an answer to your question - but in the same post, I then went on to explain that I doubted that these didy PV things would produce enough for their to be significant export but neverless went on to repeat/reinforce the answer I thought I'd just given to your question, when I wrote: ...

.... However, perhaps what you are implying, there could not be a guarantee that export wouldn't happen sometimes (sunny days with low electrical loads)

... but you responded to that with:

I'm wondering the opposite really, I think, the new product standard has yet yo be released. Could they be designed with a guarantee not to export.

...which seemed to me the same question which I thought I had already answered, at least twice

So, just to be absolutely sure, what I've been trying to say is that (rightly or wrongly), then I would struggle to see how it would be possible to ('technologically') design a 'plug-in' system which was guaranteed never to export.

I am, of course, talking about what I would regard as being a 'plug-in' system - i.e. a PV inverter that could be plugged into an 'ordinary BS1363 socket in any installation. In that situation, if the voltage output of the inverter is high enough to be able to supply local loads (i.e. slightly higher than grid voltage) then I think that it would inevitably also do at least a little exporting (since the inverter voltage had to be slightly above grid voltage) ... per 'the Laws of Physics'

Kind Regards, John

 

[denso13]

All noted and I did, I think, understand from the beginning. I was just thrown by "perhaps what you are implying", when I don't think, or didn't mean to, imply anything in anything I said/asked.

No problem though, I've maybe misunderstood that bit.

 

[JohnW2]

All noted and I did, I think, understand from the beginning. I was just thrown by "perhaps what you are implying", when I don't think, or didn't mean to, imply anything in anything I said/asked. ... No problem though, I've maybe misunderstood that bit.

Yes, on reflection, I probably didn't choose my words as well as I could have done. Rather than "perhaps what you are implying ...", I probably should have written something like "perhaps as you have already assumed/suspected..."

Kind Regards, John

 

[martygturner]

The battery box can discharge at maximum rate for battery through the socket on the front and supplement the deficit by drawing direct from the mains, so say 1 kW from battery and 1 kW from mains so a 2 kW output, and long as the output is less than 1 kW when mains is disconnected it will operate like an UPS, but since it will allow a mixture of mains and battery as it has grid tied, it can allow you to use part solar generated and part from grid.

The problem I have is the English, both types are tied to the grid, but one type back feeds the other type does not, I don't know of a phrase to differentiate between the two. They both grid tie.

As to feed into grid, as far as I am aware, my solar does not have an option to reduce its output so it does not feed into the grid, if my battery state of charge is below 100% then that will be charged first, and if my immersion heater calls for heat, that will also happen before and feed into the grid, but I have no way other than turning it off, or for the grid to be out of range, to turn the output off, at the moment 1 kW is going into the grid.

Only way not to feed into the grid is with say a 300 watts panel and a 350 watts back ground load.

oh come on thats rubbish... the only way to not feed the grid is to match the supply to the load... All inverters have export limitation - which can be set to ZERO or self consume mode with no export... its one of the standards for grid tied inverters to have a registration for grid connection they HAVE to have it, I would suggest you read the manual.

Tell me you inverter and I will tell you the settings... different manufactures call it different things - backflow, export limit, offgrid etc etc.

 

[ericmark]

oh come on thats rubbish...

Grid tie can mean two completely different things, the first grid tie inverters I saw were designed for canal narrow boats, as typical shore outlet was rated at 6 amps, and to run a washing machine needed 13 amps, so the inverter went between the shore supply and the narrow boat sockets, plus connected to battery, so it could draw 6 amps from shore, and rest from the battery, and once load reduced, it would recharge the battery.

We also see the standard UPS supply, same idea, it does sync to the grid so is grid tied, but no way can it back feed.

We also see EPS units which do the same, but slightly slower changing over mains to battery. Non of the above can put energy back into the mains supply.

But we also have grid tie inverters which can back feed, and use the existing sockets to supply the house, unlike the above, when mains fails, the output also has to fail in the main.

There are versions with two outputs, mine is one of those, so I have 4 sockets and a FCU which will remain powered with a mains failure, but most sockets in the house will fail with the mains.

While we have mains, the 4 sockets and FCU are in sync with the mains, so are grid tied, but not in the same way as rest of sockets in the house.

Problem is, quick glance they look the same, this one

does not back feed, and this one does

and one has to read the spec very carefully to work out which is which.

 

[ericmark]

Is this going a bit OTT? Hope not all plug in solar.

 

[JohnW2]

We also see the standard UPS supply, same idea, it does sync to the grid so is grid tied, but no way can it back feed. .... We also see EPS units which do the same, but slightly slower changing over mains to battery. Non of the above can put energy back into the mains supply.

If some box cannot "back feed" ("put energy back into the mains supply", "export") then there surely is no reason on earth why it needs to be 'grid tied', is there.

"Grid tying" is all about getting the inverters output to match the frequency, phase and (approximately) voltage to that of the grid supply - so that there is not a 'big bang' when the two are connected, isn't it?

 

[ebee]

"Grid tying" is all about getting the inverters output to match the frequency, phase and (approximately) voltage to that of the grid supply - so that there is not a 'big bang' when the two are connected, isn't it?

That`s what I thought although I have not delved into it in a big way as such.

 

[JohnW2]

That`s what I thought although I have not delved into it in a big way as such.

Quite. Maybe some people (like eric) have come up with some different/additional meaning of "grid tied" but what I've just descibed is what (all) I have always taken it to mean!

 

[ericmark]

"Grid tying" is all about getting the inverters output to match the frequency, phase and (approximately) voltage to that of the grid supply - so that there is not a 'big bang' when the two are connected, isn't it?

Correct, you must remember like I do, putting a generator on line, watching the three lamps and waiting for the centre green at which point throwing in the breaker, then increasing the revs so to take up the load. Being careful not to over do it, or a generator would trip out on reverse power.

Including looking at the quartz clock and the frequency clock and adjusting the output, so all frequency clocks showed the right time.

But the national grid is not quite the same. And the inverter grid ties just so it can switch between grid and inverter at any time, it does not need to back feed even 1 watt, it is like just holding the spectroscope at the point when the lever can be put in, without actually throwing the switch.

 

[JohnW2]

But the national grid is not quite the same. And the inverter grid ties just so it can switch between grid and inverter at any time, it does not need to back feed even 1 watt ....

As I said, if grid and inverter output are never going to be connected (grid-tied "just so that it can switch between grid and inverter at any time"), I don't see why the inverter has to be 'grid tied' (with respect to frequency, phase or voltage). What am I missing?

 

[ebee]

Ditto

 

[bernardgreen]

Provided there is no possibity of the change over switch connecting the grid to the invertor output ( even as a transient ) when the switch contacts are changing over I agree with JohnW2