Rooftop Solar on the Australian Grid

wattmatters

Solar Addict
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
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
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.
 
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wattmatters

Solar Addict
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
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.
 

wattmatters

Solar Addict
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.
The limitation is cost. Why over capitalise with multiple inverters when one will do? Why have extra inverters just to pass enough grid power through when one normal grid tied inverter can do the job anyway?

In our cities the grid is very reliable, so most are not that concerned with an expensive backup option. But grid tied solar - the financial benefit is a no brainer in our market. That's why nearly 30% of homes have one.

Where I am though we get fairly regular outages, hence building my off-grid system which can supply power to our 3 buildings via a transfer switch when needed.

If I really want I could leave the transfer switch in the backup position and the off-grid system can operate in utility pass through mode with UPS cut over if the grid supply is cut. Meanwhile non-critical loads are not supplied via the backup, and if the grid comes back they will too, including the grid tied inverter.

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"
Yes it's an often misunderstood concept.

I have no illusions that my grid tied inverter will go off-line when the grid does. But rather than spend $15,000 to have a grid tied battery system with grid isolation and backup capability which will never payback in my lifetime, I built an off-grid system to provide backup for a fraction of the cost. As a bonus I've taken some load off-grid (pool pump) to use the otherwise spare PV capacity.
 

mrzed001

Voice of reason
The limitation is cost. Why over capitalise with multiple inverters when one will do? Why have extra inverters just to pass enough grid power through when one normal grid tied inverter can do the job anyway?
I think 50A / phase bypass is more than enough for residential use.
That is 150A for this 3 phase unit. I do not think you use 33kW in any given time in a home :)
Also this is only limits the protected load side. The green unprotected load side you can have as much as your main can handle.


In our cities the grid is very reliable, so most are not that concerned with an expensive backup option. But grid tied solar - the financial benefit is a no brainer in our market. That's why nearly 30% of homes have one.

Where I am though we get fairly regular outages, hence building my off-grid system which can supply power to our 3 buildings via a transfer switch when needed.
Or you could build a hybrid system.
One other hybrid solution is the grid-tie + UPS solution. I am doing this myself. I have to because the EVE cells I can not put outside ... and the solar array is far from the house. Also the off-grid inverter is an 5048MK and that is a double conversion Online UPS (own clear sinus wave)

grid_tie_UPS.jpg

As you can see here on the exactly same spots the green unprotected load connects, and the purple protected load connects.
The only difference is that the grid-tie is a separate unit. This system has cons and pros against the one unit hybrid.

If I really want I could leave the transfer switch in the backup position and the off-grid system can operate in utility pass through mode with UPS cut over if the grid supply is cut. Meanwhile non-critical loads are not supplied via the backup, and if the grid comes back they will too, including the grid tied inverter.
Even more the MPP Solar inverters not only do bypass ... they doing it with power production on that line.
Have inner limiter. So power comes in into the inverter from grid, PV power comes in ... and out goes to the house all the PV power and a little bit from the utility power.

Yes it's an often misunderstood concept.

I have no illusions that my grid tied inverter will go off-line when the grid does. But rather than spend $15,000 to have a grid tied battery system with grid isolation and backup capability which will never payback in my lifetime, I built an off-grid system to provide backup for a fraction of the cost. As a bonus I've taken some load off-grid (pool pump) to use the otherwise spare PV capacity.

Why $15.000 battery?
These one unit Hybrid inverters use the same 48V battery.

hibrid_panel.jpg
You buy 16 cells of EVE/Lishen/CATL and you have your battery for it.
Like $3000 for 16pcs of 280-300Ah cells with BMS.

The inverter is not cheap but compared to Sol-Ark it is

A one phase 5kW inverter is $1400

A 3 phase 10kW inverter is $2390

And you connect your EVE cells to it and your Solar panels and the main and protected load panel ... and your system is ready.
(of course you will need the contract with the grid utility company ... but it is exactly like with a grid-tie inverter ... since it is a grid-tie inverter for them)
 
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wattmatters

Solar Addict
Like $3000 for 16pcs of 280-300Ah cells with BMS.
$15k is the minimum cost of decent sized grid tied 3-phase battery system with backup capability, professionally installed and meeting all battery connection standards.

Yes I can go DIY for a lot less, but once you go grid tied = much greater compliance costs and DIY is no longer a sensible option. Even at $3k for cells and a BMS there will be quite an expense to make it compliant for grid connection. Must be installed by qualified professional. Approvals etc.

Off-grid there are still requirements but not such an issue. Let's say it's $4k all up. Once you are off-grid the capacity utilisation drops. I don't know why I'd bother - the payback on that for us is still going to be 15+ years. Battery economics sucks here.

Plus I already have a great grid tied inverter, I'm not going to replace it.

Hence I went with a low cost solution. 2nd hand solar PV and rails, low cost off-grid inverter, repurposed SLA batteries from data centre, transfer switch which creates a single phase supply for essential loads and isolates them from the grid. Costs about the same as the generator I used to use (and which now provides redundancy).
 

wattmatters

Solar Addict
I've done quite in-depth modelling of battery economics for us - I have 3 years of 5-min interval data on consumption, production, import and export and built a battery simulation model. I can simulate a battery with given specifications (capacity, reserve setting, charge/discharge limits, round trip efficiency) and I'll know how it would perform, technically and financially.
 

mrzed001

Voice of reason
$15k is the minimum cost of decent sized grid tied 3-phase battery system with backup capability, professionally installed and meeting all battery connection standards.

Yes I can go DIY for a lot less, but once you go grid tied = much greater compliance costs and DIY is no longer a sensible option. Even at $3k for cells and a BMS there will be quite an expense to make it compliant for grid connection. Must be installed by qualified professional. Approvals etc.
This part I do not understand.
Yes they are extremely complex and expensive battery systems like LG Chem Resu 10h (400Vdc). I wrote (mostly translated to English) a post about it and its dissection, parts, etc ...

Usually utility does not care about battery, only the inverter that is connected to the grid (at least here).
What criterias and approvals are there ?

But there are simple battery solutions like Pylontech 48Vdc battery systems. Really not more than cells and BMS in a box. Has all the UL, CE, ... certificates. Plug-and-play assembly.
And from that one 3,5 kWh 48V unit is €1600. Also can be paralleled.
Also ideal for MPP Solar off-grid and one unit Hybrid inverters. They even have the setting in them, communicate directly with Pylontech BMS.


Off-grid there are still requirements but not such an issue. Let's say it's $4k all up. Once you are off-grid the capacity utilisation drops. I don't know why I'd bother - the payback on that for us is still going to be 15+ years. Battery economics sucks here.

Plus I already have a great grid tied inverter, I'm not going to replace it.


Hence I went with a low cost solution. 2nd hand solar PV and rails, low cost off-grid inverter, repurposed SLA batteries from data centre, transfer switch which creates a single phase supply for essential loads and isolates them from the grid. Costs about the same as the generator I used to use (and which now provides redundancy).

That is the grid-tie + UPS hybrid solution.
So you already building it.



I've done quite in-depth modelling of battery economics for us - I have 3 years of 5-min interval data on consumption, production, import and export and built a battery simulation model. I can simulate a battery with given specifications (capacity, reserve setting, charge/discharge limits, round trip efficiency) and I'll know how it would perform, technically and financially.
I simply use the EU's solar calculator. Can be used almost anywhere in the globe (except most of Australia where it does not have stored radiation data so only calculates based on latitude).
https://re.jrc.ec.europa.eu/pvg_tools/en/#PVP
It has on-grid and (separated) off-grid calculators. And gives pretty precise forecasts.
 

mrzed001

Voice of reason
Grid tie means it can push power to the grid. This cannot do that, only draw power from the grid.
The grid-tie part (inverter) does the selling/pushing ... the off-grid/UPS part (inverter) the battery based constant power.
It is a 2 unit hybrid system :) See previous pic.
 

wattmatters

Solar Addict
What criterias and approvals are there ?
For a start there is the Australian Standards documentation for battery installations. It's a long and detailed document behind an expensive paywall which I have no intention of purchasing for you. Also, you can't just add inverters to grid tied connections. Adding inverter capacity is not always permitted. To add a battery in such situations mean replacing perfectly functioning equipment with a even more expensive hybrid.

In lieu of the actual standards documentation here's an article however which might shed some light on the standards in place:

It's not a particularly friendly regulatory environment for DIY systems with enough power and capacity for home use. Small hobby kits are no big deal.
 

mrzed001

Voice of reason
For a start there is the Australian Standards documentation for battery installations. It's a long and detailed document behind an expensive paywall which I have no intention of purchasing for you.
No need. If I want to read it I ask a colleague from there to send me. I do not care enough to read 500+ pages of raw material. The summary was enough ;)
It seems to be over protective. You can not have a DiY 48V system, because for that you need at last 60V MPPT and solar panels. And that has to be done by electrician.



Also, you can't just add inverters to grid tied connections. Adding inverter capacity is not always permitted. To add a battery in such situations mean replacing perfectly functioning equipment with a even more expensive hybrid.
You do not add the off-grid inverter to the grid-tie inverter ....
They are SEPARATE units working separately. They are not AC Coupled.
The off-grid can not generate power to the grid.


In lieu of the actual standards documentation here's an article however which might shed some light on the standards in place:

It's not a particularly friendly regulatory environment for DIY systems with enough power and capacity for home use. Small hobby kits are no big deal.

It is a really DiY hostile regulation. With only two 36V solar panels in series you already need an electrician.
Does not differentiate between NMC, LiPo and LFP batteries.
Who wrote this? The coal industry ?
 

wattmatters

Solar Addict
The grid-tie part (inverter) does the selling/pushing ... the off-grid/UPS part (inverter) the battery based constant power.
It is a 2 unit hybrid system :) See previous pic.
I get that but it would mean the battery can only supply the circuits on the "essential" loads board.

Apart from the grid backup scenario, I see little point in buying an expensive lithium chemistry battery and control system for it to only be able to supply a portion of our loads. Battery economics suck enough as it is without dropping capacity utilisation down the toilet.

I have 3 buildings to supply. For a "permanent" installation with an off-grid UPS inverter feeding essential loads we could probably squeeze by with a 3-phase 8kW hybrid UPS inverter to make sure it's not a supply choke point, but 10kW might be safer.

Plus a complete rewire of main circuit board to split the loads. Plus a lithium battery system now connected in a manner which will take decades to payback (since it is not able to supplying energy to all loads, especially the power hungry ones). And then I'd also need to add extra off-grid PV capacity if I want to cycle such a battery daily instead of having it idle as standby backup with just enough PV for a top up charge.

Don't get me wrong, I've thought quite a bit about exactly what you propose but the numbers just don't stack up. At least not yet.

For now we'll live with a (cheap) 4kW off-grid hybrid inverter with 18.2kWh of (2nd hand data centre) SLA batteries and 2.2kW of (pre-loved) PV to cover us during outages and the occasional/special circumstances where we might choose to operate it in UPS mode (e.g. planned grid outages or when the grid is flakey due to storms). The small PV system keeps the pool pump running and batteries in a state of readiness for the inevitable outage. Summer is coming, it's only a matter of time before storms take out a local power line somewhere.

I have the sparky coming tomorrow to complete some of the wiring set up so the UPS mode will operate correctly (should be an easy fix but it has to be a sparky to sort it, just like I had him do the AC output wiring). Only other thing I am doing after that is upgrading the fire protection of the battery/inverter housing and to also upgrade the battery circuit protection with better quality fusing and disconnects than I currently have in place.
 

mrzed001

Voice of reason
I get that but it would mean the battery can only supply the circuits on the "essential" loads board.
Exactly. And not :)
You can separate (L+N) your house circuits and choose with 1-0-2 switch who should give power to that load.
eaton_1_0_2.jpg

Like I separated the cooktop and usually use it from grid. But if there is a big blackout I can switch it manually to UPS.
The coffee machine is constantly on UPS :LOL:
 

mrzed001

Voice of reason
LOL, I wouldn't put it past them.

Pretty much anyone putting together a 48V system here is walking a fine regulatory line. I had a qualified electrician install key parts of the wiring.
And I think electricians do not grow on trees there also ... so the already overused guys have now a lot of unnecessary low V work to do.
 

wattmatters

Solar Addict
Like I separated the cooktop and usually use it from grid. But if there is a big blackout I can switch it manually to UPS.
Nice thought but no real need. The only circuits deemed "non-essential" and which remain on the grid side only are those which have a dedicated circuit with too high a power draw for the off-grid system to supply. Off-grid supply limit is 4kW. Ample power for outage coverage, but not sufficient for ongoing regular household operation.

Non essential circuits includes oven, induction stove, ducted aircon, another large aircon system, plus of course the 3-phase grid tied inverter and the circuit providing power to the off-grid inverter (can't have that feeding power to itself). Resistive element hot water storage system as well - it's a utility switched controlled load and a separately metered circuit already.

Else every GPO and light has backup. The backup also extends to supplying power via 3-phase sub-mains to two other buildings, and the high power draw appliances in those buildings will have backup power available, so they need to be manually managed. Not difficult but it would be problematic if we were operating in UPS mode and there was an outage while these high power draw appliances were on. Hence use of the UPS mode will be for specific circumstances.

It's possible to change the 3-phase sub-mains over to individual phase switching to enable isolation of one or two phases in each outbuilding. But for now I have a functioning backup which is simple to operate and hasn't cost the Earth to build.

Enough juice in the batteries to cover ~15 hours of typical essential loads to 50% DOD, plus the solar PV supplemental supply to extend that and the generator can be fired up to recharge batteries / pass through power if we need for a longer outage. Most outages are a few hours. Occasionally much longer.

One of the reasons for having just one transfer switch is the simplicity of operation for others. If I am not here, they know all that's required is to flip one switch and backup will be operating immediately. All the circuits which needs to be isolated from backup have been taken care of, with exception of a few things in the outbuildings (and they know that) they know to ensure are off.

And I think electricians do not grow on trees there also ... so the already overused guys have now a lot of unnecessary low V work to do.
Yeah, they are stupid busy. Unless its an emergency, it takes months to get a service appointment. Trades of all kinds here are flat out. We have a 1+ year wait for a builder.
 

wattmatters

Solar Addict
Well the records keep coming. Briefly today the Australian national grid hit >60% renewable energy supply, and on a Monday no less.

Screen Shot 2021-09-20 at 8.54.54 pm.png
 
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