Rooftop Solar on the Australian Grid

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
8,432
And grid management isn't just about supply, there is smart demand management as well.

This is practically the most important. It is so large scale and easy to deploy.
Many distributed loads with low-level control signals already available (especially A/C systems) Those can disconnect instantly at any time. In the case of A/C and refrigeration, it can come back online on request, after a delay. Water pumping into holding tanks can also be controlled. Lighting can be dimmed. With a bit more invasive control, computers can vary their power consumption by slowing performance.

To the extent loads can be controlled to use available power, cost per kWh goes down. The grid becomes more resilient.
During times of major production loss (power plant failure), turning off A/C and keeping it off would be preferable to shutting down the grid.

In California, a new law requires rooftop solar on all new homes (or sharing in community arrays). Of course, rooftop costs more per kW, like 2x or 3x what large scale does, so we only get 1/2 or 1/3 as much production for our money.
Natural gas hookups are prohibited for new homes, must use electric heat.
If engineers not bureaucrats made the decisions, we would connect natural gas and have hybrid gas/electric heating appliances. Then they could be commanded to switch energy source for grid resiliency and support a higher percentage of renewable utilization. (Similarly, hybrid cars enable a higher percentage electric miles driven compared to a fleet of electric-only cars plus ICE-only cars.)
 

mrzed001

Voice of reason
Joined
Apr 10, 2020
Messages
721
Location
Hungary - EU
you are from poland correct ?

Nope. Hungary (it is on my profile)

then you of all people should know what happens when nuclear ( for what ever reason) goes south ( chernobyl ? ) , that is not even mentioning storing the waste material..

And I know. May 1st is a national holiday here. The celebration of work.
At that day at may 1st 1986 when the nuclear cloud reached Hungary most of the Hungarians were on streets, on bazaars and on street festivals all over the country.
And as usually in this day there was a lot of sunshine, a light rain, then a lot of sunshine again.
Nobody warned us. We also were on a street festival eating hot dog ... and we also get some of the radioactive rain, eat later the radioactive salads, etc ...

But the cause of the meltdown was human error and poor design. Since then more hundreds nuclear power plants work flawlessly.
In France 56, in USA 94 reactors ... overall 440.

Just because a Boeing 747 fell from the sky (pilot error) does not mean that we should ban all 747 ... or flight all together.


while "clean" in co2 , not so clean in other ways.
You know that if you put the used cells into a pool (they do) ... you can literally swim in it without getting exposed to radiation?

And do you know how many is the radioactive waste material?

For one block, yearly raw / processed:
- high active : 0,5 m3 / 5 capsule
- middle active : 11 m3 / 20 barrel
- low active : 70 m3 / 140 barrel

Do you know how many people premature death is caused by the coal plants air pollution?

need i remind you a part of robbert oppenheimers speach " now i have become death, the destroyer of worlds" ?

Oppenheimer was the project leader for the nuclear bomb ... and had nothing to do with the nuclear power plants.
If you want to quote someone who made the nuclear power plants possible why do not quote Leo Szilárd (Hungarian) or Enrico Fermi (Italian) for example?
Also the Manhattan project was Leó Szilárd's initiative with Albert Einstein's support.
Or you could cite Ede (Edward) Teller (Hungarian) who made the hydrogen bomb.
He also ban the Chernobyl type reactors already in 1950 in the USA.
36 years later everyone understand that he was right.

Until fusion reactors are made (at least 30 years) we have to use fission reactors.
Of course we could burn coal instead and suffocate the planet and let global warming rage all over the globe.
But that would be a bad solution.
 

houseofancients

Solar Addict
Joined
Nov 29, 2019
Messages
559
Nope. Hungary (it is on my profile)



And I know. May 1st is a national holiday here. The celebration of work.
At that day at may 1st 1986 when the nuclear cloud reached Hungary most of the Hungarians were on streets, on bazaars and on street festivals all over the country.
And as usually in this day there was a lot of sunshine, a light rain, then a lot of sunshine again.
Nobody warned us. We also were on a street festival eating hot dog ... and we also get some of the radioactive rain, eat later the radioactive salads, etc ...

But the cause of the meltdown was human error and poor design. Since then more hundreds nuclear power plants work flawlessly.
In France 56, in USA 94 reactors ... overall 440.

Just because a Boeing 747 fell from the sky (pilot error) does not mean that we should ban all 747 ... or flight all together.



You know that if you put the used cells into a pool (they do) ... you can literally swim in it without getting exposed to radiation?

And do you know how many is the radioactive waste material?

For one block, yearly raw / processed:
- high active : 0,5 m3 / 5 capsule
- middle active : 11 m3 / 20 barrel
- low active : 70 m3 / 140 barrel

Do you know how many people premature death is caused by the coal plants air pollution?


Oppenheimer was the project leader for the nuclear bomb ... and had nothing to do with the nuclear power plants.
If you want to quote someone who made the nuclear power plants possible why do not quote Leo Szilárd (Hungarian) or Enrico Fermi (Italian) for example?
Also the Manhattan project was Leó Szilárd's initiative with Albert Einstein's support.
Or you could cite Ede (Edward) Teller (Hungarian) who made the hydrogen bomb.
He also ban the Chernobyl type reactors already in 1950 in the USA.
36 years later everyone understand that he was right.

Until fusion reactors are made (at least 30 years) we have to use fission reactors.
Of course we could burn coal instead and suffocate the planet and let global warming rage all over the globe.
But that would be a bad solution.
the reason i quoted oppenheimer, is that he first made it very clear to the world that some tech simply should not be used.

i understand there are a lot of nukes active, and have been for many years without incident, however , it just takes 1 catastroph to ruin a complete continent, or worse, the planet.

i'm quite principal on nuclear, the good simply doesnt outweight the potential for disaster
 

mrzed001

Voice of reason
Joined
Apr 10, 2020
Messages
721
Location
Hungary - EU
Coal production is relatively slow to ramp up/down. Some are better than others.
I was speaking about the coal based power production :)
That can be scaled and turned up/down fast as you need it.


Meanwhile renewables can be curtailed or brought back online pretty darn quickly
Not so fast.
Grid-tie systems have a required time to wait after a power loss.
The IEEE 1547 specified grid reconnect delay is 300 seconds (5 min).
In some inverters in some special cases it can be set lower, even to 30 sec. But usually it is the factory set 300 sec.

(that's the thing with having more renewable capacity than is needed at any time - something you can do when it's so bloody cheap and fast to build), while batteries are responding within milliseconds with their FCAS activity.
And we love them for that :)


Gas peaker plants have lost a significant amount of earnings to batteries and can no longer extract exorbitant fees for rapid response any more. The batteries are doing it better, faster, more reliably and for much lower cost.
Yes if enough battery then not as much gas is needed (maybe none). But it will be years later that such a huge amount of battery capacity is available.

And grid management isn't just about supply, there is smart demand management as well. e.g. in NSW the Tomago aluminium smelter (which currently draws ~ 850MW) is moving away from steady state coal supply to entirely renewable electricity supply as they rework their plant to produce based on when the energy is available. No longer will it be "baseload demand". That alone is one massive customer at 10-15% of the state's total electricity demand.
I wrote about the event when the European grid separated into north and south part ... and almost collapsed both.
Then in the north like France big loads big companies have been shut down to stabilize and reconnect the two grid parts.
There was a bit of an indignation later saying we are not a communist country so how do you dare to shut down our facilities :)
Usually this is the last utility makes ... to shut down someone's power.
(but of course they have a disaster plan what to shut down, at which order ... and only the last is the residential)

South Australia's grid is now at 61% renewables over a full year. There is zero hydro and zero coal. Battery discharging (including Hornsdale) only represented 0.6% of grid supply. Yes they have their contingency gas (and the odd diesel) plants in place if/when needed but it's affordable because the cost of renewables is so good now. Natural gas is their fill in fuel but it's contribution to their grid is dropping like a stone. Amazingly the amount of firming storage capacity required to get to 60% renewables has been bugger all. Their only real reliability problem was caused when major transmission infrastructure got taken out by storms. Much more storage is coming as gas's contribution will continue to decline.
You know at least there is a lot of sun and wind. In the middle of Europe there is almost no wind.
Solar is like the mood: sometimes great, sometimes bad (changing even more times in a day)
 

mrzed001

Voice of reason
Joined
Apr 10, 2020
Messages
721
Location
Hungary - EU
the reason i quoted oppenheimer, is that he first made it very clear to the world that some tech simply should not be used.

i understand there are a lot of nukes active, and have been for many years without incident, however , it just takes 1 catastroph to ruin a complete continent, or worse, the planet.

i'm quite principal on nuclear, the good simply doesnt outweight the potential for disaster

I think if we did not use nuclear power plants in the last 50 years then we would be suffocating right now.

https://www.ucsusa.org/resources/coal-and-air-pollution
There is so much data in this article that I can not decide what to highlight ...
US coal power plants emitted (2014)
- 197,286 tons of small airborne particles (measured as 10 micrometers or less in diameter)
- 41.2 tons of lead
- 9,332 pounds of cadmium, and other toxic heavy metals.
- 576,185 tons of carbon monoxide, which causes headaches and places additional stress on people with heart disease.
- 22,124 tons of volatile organic compounds (VOC), which form ozone.
- 77,108 pounds of arsenic. For scale, arsenic causes cancer in one out of 100 people who drink water containing 50 parts per billion
 

wattmatters

Solar Addict
Joined
Apr 16, 2021
Messages
879
You know at least there is a lot of sun and wind.
Well this is a thread about rooftop solar PV on the Australian grid. ;)

As an aside, South Australia have introduced new rooftop solar inverter standards to help with this rapid change in supply dynamics.

In SA new (or upgraded) rooftop solar will need to meet the new standard and I expect in the other states will follow.

Essentially all new grid tied inverters must have the ability for solar export to be curtailed by the central authority during times of need. These are those peak production hours during massive oversupply days. Mild Spring Sundays are classic examples. Great for production but no one is using their air con and being a Sunday industry/commercial demand is down.

The trade off for this is you will now be permitted to install a much larger solar PV system and have a much higher export limit.

It's a smart move because it enables way more solar PV to be available for most of the time (and significantly increase PV output when conditions are less favourable, e.g. Winter, cloudy days) but provides a smart mechanism to help ensure grid stability when needed. You may also opt out of the centralised control option but you will be saddled with a very small export limit, much lower than previously permitted.

In SA their off-peak tariff is 10am to 3pm. Loads are shifting. Water storage heating is moving to daytime. etc.

I think the new regulations are a bit late and this needs to comes to other states heading down the same renewable growth curve. 1 in 3 homes in SA already have a rooftop solar PV system.

In Western Australia they just put hard limits on systems size and exports and have reduced feed in tariffs to 3c/kWh. Rooftop solar PV is also big over there - brilliant solar PV conditions.
 
Last edited:

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
8,432
Not so fast.
Grid-tie systems have a required time to wait after a power loss.
The IEEE 1547 specified grid reconnect delay is 300 seconds (5 min).
In some inverters in some special cases it can be set lower, even to 30 sec. But usually it is the factory set 300 sec.

Only takes a stroke of a pen, to eliminate problems caused by the stroke of a pen.

UL-1741 SA (US, Calif) provides for some degree of ride-through grid voltage/frequency excursions, and support of stability.
The right parameters should make the grid more stable.
Having excess PV with some of it curtailed all the time would allow it to pick up load additions, and to keep working during times of partially obscured sun. That's how my home system works when grid is down (100% PV, small battery backup). Could work with lots of PV, some amount of hydro or other rotating generators.
 

mrzed001

Voice of reason
Joined
Apr 10, 2020
Messages
721
Location
Hungary - EU
Well this is a thread about rooftop solar PV on the Australian grid. ;)
Of course, you are right :) I just want to add a wider, a global perspective. You know the motto: thing globally act locally.

As an aside, South Australia have introduced new rooftop solar inverter standards to help with this rapid change in supply dynamics.

In SA new (or upgraded) rooftop solar will need to meet the new standard and I expect in the other states will follow.

Essentially all new grid tied inverters must have the ability for solar export to be curtailed by the central authority during times of need. These are those peak production hours during massive oversupply days. Mild Spring Sundays are classic examples. Great for production but no one is using their air con and being a Sunday industry/commercial demand is down.

The trade off for this is you will now be permitted to install a much larger solar PV system and have a much higher export limit.

It's a smart move because it enables way more solar PV to be available for most of the time (and significantly increase PV output when conditions are less favourable, e.g. Winter, cloudy days) but provides a smart mechanism to help ensure grid stability when needed. You may also opt out of the centralised control option but you will be saddled with a very small export limit, much lower than previously permitted.

In SA their off-peak tariff is 10am to 3pm. Loads are shifting. Water storage heating is moving to daytime. etc.

I think the new regulations are a bit late and this needs to comes to other states heading down the same renewable growth curve. 1 in 3 homes in SA already have a rooftop solar PV system.

In Western Australia they just put hard limits on systems size and exports and have reduced feed in tariffs to 3c/kWh. Rooftop solar PV is also big over there - brilliant solar PV conditions.

I am not sure to follow but if it is what I think it is then ... we already had a debate about that in the EU and dismissed the idea.
So is it a central/centralized control for grid-tie inverters ?
To one control authority to be able to throttle down solar inverters like residential and solar power plants ?

I try to remember all the things and arguments made against that :

- hackers: all inverters need online internet connection. SPoF is the central system. If hacked ALL solar production can be stopped with a keystroke. Such a huge power loss can not be compensated from other sources. Not even from enormous batteries. So with one keystroke a hacker can bring down the complete grid !

- internet loss: internet providers can have technical problems and internet can be not available for short or longer times (user side). Central authority can give a command having not a clue what will happen. Like issuing an order to all inverters to lower production to 70%. Unknown number of inverters will receive the order and respond to that. This can result in over lowering and not lowering enough (even in the same time)

- localization: Even in a smaller grid can occur local shortages and local surpluses. In an already local shortage line the PV production is lowered then the connecting transfer lines can be overcharged/overused/overdrive and transfer stations will do the safety disconnect. The best power is still the locally made and locally used one.

- localized control: can every inverter with its grid hierarchy registered into a database and localized orders issued. Like only on that substation or city or on that district or on that street. Too complex. The grid hierarchy is not a constant. Criss-cross backup lines providing structural stability to the grid, preventing blackouts if parts of it is destroyed.
This could work, but hell of a job to do it and maintain it.

- money: you earn money by selling power to the grid. Who will compensate you for the lost money? Why you have to pay for the fault of the grid utility company? It is his role to manage the grid. Could have stopped or turned down coal plants. Why you ? (because you are easy to contorol and did not pay for politicians campaign ... they did)

- Security: you have to make your inverter online, put it out to the internet. And in a well known way. Easy to detect. Hybrid inverters also know your consumption so hacker knows when you are home or not.

And finally: There is (at that time) not a single grid-tie inverter that supports this function.
You need a new secure protocol, a new implementation, a new product line ....
Some inverters can be upgraded with a new firmware, some are not.
But for every inverter a separate firmware is needed. It is time, manpower and money.
And you need a big apparatus to control and maintain this whole system.
 

wattmatters

Solar Addict
Joined
Apr 16, 2021
Messages
879
And finally: There is (at that time) not a single grid-tie inverter that supports this function.
That's funny because they've already used it earlier in this year to switch off rooftop solar PV systems in SA during a low grid demand event. About 10MW of rooftop solar PV was turned off via remote network control. Another 30MW was done through local substation voltage control. Grid scale production was also curtailed. All new grid tied rooftop solar PV inverters in SA are required to meet the new standard.

 

wattmatters

Solar Addict
Joined
Apr 16, 2021
Messages
879
money: you earn money by selling power to the grid. Who will compensate you for the lost money?
As part of the quid pro quo, people are now allowed to install much larger systems and export more than ever before. It's only during extreme low grid demand events when such curtailment will take place. It will result in there being much greater capacity available for most of the time (e.g. Winter, cloudy days, days when wind production ain't so good), while the grid can be kept secure during those low demand events.
 

wattmatters

Solar Addict
Joined
Apr 16, 2021
Messages
879
so hacker knows when you are home or not
Not sure what data on the output from a solar PV array says about whether or not someone is home? The array's production isn't dependent on anyone being home. Also every meter on every solar home in SA (pretty much in the whole country and every household in Victoria) has a smart meter continuously sending data via various communication protocols already.

- internet loss: internet providers can have technical problems and internet can be not available for short or longer times (user side).
As explained, there is more than one way to curtail PV production. Controllable substation voltage also exists. It's a bit cruder and less targeted than adjusting production levels via direct control (since it will affect different homes to different degrees) but this isn't an all eggs in one basket approach.
 
Last edited:

mrzed001

Voice of reason
Joined
Apr 10, 2020
Messages
721
Location
Hungary - EU
That's funny because they've already used it earlier in this year to switch off rooftop solar PV systems in SA during a low grid demand event. About 10MW of rooftop solar PV was turned off via remote network control. Another 30MW was done through local substation voltage control. Grid scale production was also curtailed. All new grid tied rooftop solar PV inverters in SA are required to meet the new standard.


As you also know there is only 2 way today to shut down Grid-Tie inverters or lower its production utility side:
- High Hz
- High Voltage
This is the only two solution for the grid utility.
None of them is really "good" or "safe".
Hz deviations can even more easily kill user equipments than raised Voltage.

The only real control solution would be the direct inverter communication through internet. And I wrote a lot about its dangers and needs.


Yeah well they are just doing it in SA. No debate. One state, one jurisdiction, one power network company.
We are doing ... something like it (silently). Like transformers with limited backfeed capabilities. And then if there is a lot solar production on load side then that raises Voltage there ... and that automatically shuts down some inverters. So not centralised, not controllable from central ... a simple local automatism.



As part of the quid pro quo, people are now allowed to install much larger systems and export more than ever before. It's only during extreme low grid demand events when such curtailment will take place. It will result in there being much greater capacity available for most of the time (e.g. Winter, cloudy days, days when wind production ain't so good), while the grid can be kept secure during those low demand events.
I still do not know what type of control they want to use over the inverters ?
The plan is good but the devil is still in the details and in the implementation.


Not sure what data on the output from a solar PV array says about whether or not someone is home? The array's production isn't dependent on anyone being home. Also every meter on every solar home in SA (pretty much in the whole country and every household in Victoria) has a smart meter continuously sending data via various communication protocols already.
I wrote Hybrid inverter. You know the single unit grid-tie + off-grid inverters (like Voltronic Infinisolar or SAJ H1).
All your house load is going through that inverter. A real house UPS. If you have to put that out to the internet and someone hacks into it then they will know how much is your actual used W (you are home or not).
They also can shut down all your power in the house anytime they want (simple setting as you can do, no hacking needed).
In worst case can change higher battery charge V and Amps and release the magic smoke (LFP) ... or blow it up if it is an NMC or LiPo or Lead battery.
So not one IT auditor will say this is a safe solution.

As explained, there is more than one way to curtail PV production. Controllable substation voltage also exists. It's a bit cruder and less targeted than adjusting production levels via direct control (since it will affect different homes to different degrees) but this isn't an all eggs in one basket approach.
I think I listed all the possibilities.
Yep I forgot the 4th possible way to control Solar inverters production ... or really how to stop them.
There is a bad habit utility started ... when overload (or overvoltage) then substation/transformer makes a fast off-on-off-on ... cycle.
And yes the power loss shuts down the solar inverters and they do not start for the next 5 minutes.
But this (1-1-1-1 sec) on-off-on-off-... (3-10) cycles do huge damages (spikes). Users equipments die because of that.
So I really do not recommend using this method.
 

sunshine

Solar Addict
Joined
Apr 24, 2020
Messages
456
The plan is good but the devil is still in the details and in the implementation.
The South Australian power distribution network is owned by a consortium of Chinese and Nth American interests.
KKR Hedge Fund is behind the Nth American interests. Guess which Australian State consumer pays the highest electricity bill?
 

wattmatters

Solar Addict
Joined
Apr 16, 2021
Messages
879
As you also know there is only 2 way today to shut down Grid-Tie inverters or lower its production utility side:
I can adjust the output of my Fronius inverter to the grid through a control interface. It's a simple setting. Either in % of output capacity terms or to an absolute kW limit.

Some people here are putting in place dynamically controlled systems because they are on wholesale price pass through plans. Dynamic control of their export and/or production enables them to avoid having to pay to export when prices go negative, and they are also dynamically controlling loads as well so as to import as much as they can at such times and be paid to consume. They are doing it now.

There are also quite a number of VPPs operating (virtual power plants) which are remotely controlling home battery systems such that they can operate together as a distributed grid scale battery to provide fast response services to the grid. Even Tesla operates one here but there are quite a number of them in operation.

I still do not know what type of control they want to use over the inverters ?
The plan is good but the devil is still in the details and in the implementation.
That's why they have started with pockets of the installed base, so they can test all the various options. As you say, some of the grid options (voltage/frequency signalling etc) can be a bit brutal and indiscriminate. That's why I'd much prefer a simple signal was sent to my inverter which can then control it's own ramp down.

I wrote Hybrid inverter. You know the single unit grid-tie + off-grid inverters (like Voltronic Infinisolar or SAJ H1).
All your house load is going through that inverter. A real house UPS. If you have to put that out to the internet and someone hacks into it then they will know how much is your actual used W (you are home or not).
The requirements only apply to grid-tied inverters capable of pushing power into the grid. This is 99% of rooftop PV inverters in Australia.

The sort of inverters you refer to are set up to operate as an off-grid set up only.

Anything connected to the grid which operates as a small scale generator (SSG is defined as something which supplies power to the grid) requires power distribution authority approval and is required to meet specific standards (including any set limits on capacity and export controls).

An inverter operating off-grid which does not back-feed power to the grid (even one that can pass through the grid power and operate like a UPS) is not subject to the same requirements that grid tied inverters are. As far as the grid is concerned such inverters are just a load. If the grid goes off-line, then as far as the grid is concerned that entire load has been removed from the grid (if it wasn't already sourcing power from off-grid supply).

I have both such set ups at home:
- A grid tied Fronius inverter which can pump power into to the grid. It operates in parallel with the grid supply. If grid goes down, so it does too.
- An AIO unit which operates with a separate PV array and battery. This supplies power to off-grid AC outlets plus provides backup to my home via a transfer switch, meaning those backed up circuits are completely isolated from the grid and so become an extension of the off-grid outlets. It can operate in the manner you describe, i.e. accept grid power in and pass through to output, and cut over like a UPS if grid power is cut. These operate in series with grid power and as such connected loads are limited to the output capacity of the inverter (there is no parallel supplementation of power from the grid). Provided they cannot supply power into the grid, then they are not subject to the same grid control requirements.


As to the risk hacking presents to grid stability, I see little difference between the risk of distributed rooftop solar supply being hacked and any one of the large grid power stations being hacked. They are all connected by networks and are all hackable.
 

wattmatters

Solar Addict
Joined
Apr 16, 2021
Messages
879
Guess which Australian State consumer pays the highest electricity bill?
Their retail tariffs have been fairly high in the past, but that is changing. They also have some of the cheapest retail electricity. There is a retail plan now (Globird) where the daytime tariff is just 5.5c/kWh (US4.0c/kWh). Off peak 11c and peak 29c.

Wholesale electricity prices in SA have now fallen below that in other states, driven by cheaper renewable supply.
 

mrzed001

Voice of reason
Joined
Apr 10, 2020
Messages
721
Location
Hungary - EU
I can adjust the output of my Fronius inverter to the grid through a control interface. It's a simple setting. Either in % of output capacity terms or to an absolute kW limit.
After you log in into its settings page. You do not want to give some company your login info for your own inverter ....
And as many inverter as many login page ... not easy to make it automatic.
So first you would need it developed. In a small scale allow only one inverter with this special remote control protocol.

Also it is only good for you if you have a limiter (smart meter).
Because that would be hilarious if you charge your EVs from solar, and then the utility limits your production and you have to buy the power (that you would made for yourself). :LOL:

Some people here are putting in place dynamically controlled systems because they are on wholesale price pass through plans. Dynamic control of their export and/or production enables them to avoid having to pay to export when prices go negative, and they are also dynamically controlling loads as well so as to import as much as they can at such times and be paid to consume. They are doing it now.

There are also quite a number of VPPs operating (virtual power plants) which are remotely controlling home battery systems such that they can operate together as a distributed grid scale battery to provide fast response services to the grid. Even Tesla operates one here but there are quite a number of them in operation.
I read about a Tesla pilot project ... but later nothing. It was big news: rent your battery, do nothing and earn money.
But as I read it was in US and only a pilot. Never heard about this put out live.
If you have info about it, share please :)
(also Tesla developed the protocol to be able to remotely control his own inverter ... and it was easy for them because they made both part of the communication)

That's why they have started with pockets of the installed base, so they can test all the various options. As you say, some of the grid options (voltage/frequency signalling etc) can be a bit brutal and indiscriminate. That's why I'd much prefer a simple signal was sent to my inverter which can then control it's own ramp down.
As I said this could be done. But for this they need the support of the manufacturers.
It is a development. Someone has to organize and pay for it. And nobody will do it for free.

The requirements only apply to grid-tied inverters capable of pushing power into the grid. This is 99% of rooftop PV inverters in Australia.

The sort of inverters you refer to are set up to operate as an off-grid set up only.
Nope. Real one unit hybrid inverters are both: off-grid and grid-tie at the same time.
They sell power to the grid and have protected load
(ps this is why I hate that there is no fix definition ... everyone thinks other things when say hybrid ... I am translating to English and expanding my previous "all system type description" article ... but it goes a bit slow).


This is a one unit hybrid system. You have such systems in Australia too. They have all the certificates there and here in EU too.
hibrid.jpg
The hybrid inverter has an
- AC in (connected to grid) where it can sell power to grid or can buy power and put it into battery (charger) or can bypass it to load (house)
- AC out (connected to house) where it outputs only power from PV and/or battery and/or grid.



Anything connected to the grid which operates as a small scale generator (SSG is defined as something which supplies power to the grid) requires power distribution authority approval and is required to meet specific standards (including any set limits on capacity and export controls).
If your utility has an allowed inverter list there will be a Voltronic Infinisolar. AS, VDE, ... it has all certificates.

An inverter operating off-grid which does not back-feed power to the grid (even one that can pass through the grid power and operate like a UPS) is not subject to the same requirements that grid tied inverters are. As far as the grid is concerned such inverters are just a load. If the grid goes off-line, then as far as the grid is concerned that entire load has been removed from the grid (if it wasn't already sourcing power from off-grid supply).
Here is the same.

I have both such set ups at home:
- A grid tied Fronius inverter which can pump power into to the grid. It operates in parallel with the grid supply. If grid goes down, so it does too.
- An AIO unit which operates with a separate PV array and battery. This supplies power to off-grid AC outlets plus provides backup to my home via a transfer switch, meaning those backed up circuits are completely isolated from the grid and so become an extension of the off-grid outlets. It can operate in the manner you describe, i.e. accept grid power in and pass through to output, and cut over like a UPS if grid power is cut. These operate in series with grid power and as such connected loads are limited to the output capacity of the inverter (there is no parallel supplementation of power from the grid). Provided they cannot supply power into the grid, then they are not subject to the same grid control requirements.
This hybrid inverters is like the Fronius and MPP Solar inverters combined in a single unit.
Not new, already sold since around 8 years now

As to the risk hacking presents to grid stability, I see little difference between the risk of distributed rooftop solar supply being hacked and any one of the large grid power stations being hacked. They are all connected by networks and are all hackable.
If your inverter is hacked then only your power generation can be shut down.
If the central command is hacked then it can send shutdown order to all inverters ... and bring down the whole grid.
SPoF (Single Point of Failure)
Also grid controller computers are not online.
 
Last edited:

wattmatters

Solar Addict
Joined
Apr 16, 2021
Messages
879
Nope. Real one unit hybrid inverters are both: off-grid and grid-tie at the same time.
They sell power to the grid and have protected load
And again, any inverter which is capable of pushing power to the grid must be approved for connection to the grid by the power distribution company. You have to submit an application to do that. An inverter with an electrical certification for use, while a necessary pre-requisite, is not alone sufficient to be permitted to push power to the grid.

Most of the inverters to which you are referring, while technically capable of pushing power to the grid, are not used here because it is far more advantageous to have a grid tied inverter which works in parallel with the grid supply, not in series.

Households don't want their supply limited to the output an inverter can supply/pass through. If the grid is available they want their solar to supply whatever it can and for the balance to be drawn from the grid. The sort of inverters you are referring to can't do that. Output is limited to the inverter's output capacity.

IOW those inverters are here, but they are only really used in off-grid set ups or are set up to not push power to the grid.
 

mrzed001

Voice of reason
Joined
Apr 10, 2020
Messages
721
Location
Hungary - EU
And again, any inverter which is capable of pushing power to the grid must be approved for connection to the grid by the power distribution company. You have to submit an application to do that. An inverter with an electrical certification for use, while a necessary pre-requisite, is not alone sufficient to be permitted to push power to the grid.
As the same here :)

Most of the inverters to which you are referring, while technically capable of pushing power to the grid, are not used here because it is far more advantageous to have a grid tied inverter which works in parallel with the grid supply, not in series.

And that is why it is commonly used in this setup
hibrid_panel.jpg
green: not protected load circuit, but gets power from hybrid inverter too
purple: protected load circuit
Green also goes into the house (if you want) ... I was just lazy making a more realistic diagram.
The important part is that these two circuits must be separated from each other.

Usually it means a not protected load box and a protected load box.
If you want to charge your EV you can put the charger in the unprotected side, or in blackout in the protected side.
Or use a 1-0-2 transfer switch and you can choose where it gets the power (green or purple).



Households don't want their supply limited to the output an inverter can supply/pass through. If the grid is available they want their solar to supply whatever it can and for the balance to be drawn from the grid. The sort of inverters you are referring to can't do that. Output is limited to the inverter's output capacity.
See previous. You see this is why I doing the hybrid and all system setup manual. There is a lot of misconception out in the wild.


Also these inverters have an inner bypass (AC in to AC out). That can transfer 40-50A ... per phase.
If not enough you can parallel 6 of them.
So there is really no limitation in residential usage.

For industrial usage there is the 30kW unit: https://www.mppsolar.com/v3/hv3-30k/
4 can be paralleled into 120kW.

IOW those inverters are here, but they are only really used in off-grid set ups or are set up to not push power to the grid.
As there here is also a lot of grid-tie system (almost all, slowly changing with cheaper LFP battery technology, and having a big gap in power selling and buying price).

OK this situation was funny, I try to write it down:
I was just explaining in a FB group the hybrid systems, writing like:
- the most common question that comes up weekly is "I have a solar system and still sitting in the dark in a blackout ... what can I do against it"
And after only 13 minutes a newbie (you know the never read back, write only type) is getting in into the forum and pops almost exactly same question.
:LOL:


So it is how often it comes up.
 
Top