NSW-Grid feed-in export limitations

The new system proposals that I have received all declined to give me panels to provide more than around 6.5 kW saying that is the limit that I can feed into the grid.

The SOLAR SIMULATOR on this site tells me that more panels on my roof gives more feed-in to the grid, which in turn drops my electricity bills.

Selecting 40 panels (totalling 13 kW), and mid-range dollars for both inverter and panels feeds a peak of 5.75 kW into the grid, and would bring my monthly bills to $-6 with a total system payback period of 5.4 years.

Moving the PANELS slider to the far right, 92 panels (no, I don’t have that much roof!) feeds a peak of 13 kWh into the grid, gives me a bill of $-128 and still only makes the payback period 5.6 years.

Is the SOLAR SIMULATOR wrong in saying that the grid will continue to accept more than 6.5 kW (which it does once 44 panels totalling 14.5 kW is reached, and beyond of course).

Are the prospective installers ignoring my “over-sizing“ requests to keep their quotation prices down by limiting the number of panels?

Or are they (stupidly) saying that their 6.5 kW system will be generating 6.5 kW all day and the grid will not accept any more, so there is no point in having any more panels?

Or a mixture or both? Or something else?

My head hurts!

I have the money in the bank earning nothing worthwhile in interest, when I’d be getting a larger income in the form of reduced electricity bills by spending up big on panels. This makes sense doesn’t it?

BaDaHe
NSW South Coast

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Hi there @BaDaHe

The Solar Simulator does not currently take into account a) how much solar will fit on your roof, or b) how much solar your electricity distributor will let you put on your roof.

There are lots of different rules about how much solar you can put on your roof in different locations. I highly doubt the installers are telling you fibs, given that they would love to sell you a bigger system because it’s easy money.

There is currently no easy way for the grid to not accept your solar when the grid doesn’t want it, so instead we have blunt rules in a lot of locations (and I suspect yours) that say you can’t have an inverter bigger than 5kW AC. And if 5kW is your max inverter size, then your max solar array size is 6.6kW. Annoying, but better than nothing!

I’m glad you are using our new Solar Simulator, and hope it didn’t cause too many headaches. We are working hard to improve it. I hadn’t actually considered that we might add the distributor feed-in limits to it. That might be possible. cc @Svarky, something to consider.

Cheers
Marty

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Well thank you for a clear and concise answer Marty. Not the one that I wanted, but now I understand what is going on!

BaDaHe
NSW South Coast

@BaDaHe this is a good question.

I hope Marty helped to clarify the difficulties around estimating solar generation and grid feed-in.

Do you know if you have a single-phase or 3-phase grid connection? The reason I ask is because a 3-phase grid connection typically allows up to 15kW grid export (5kw per phase) while a single-phase grid connection is limited to max 5kW grid export.

If you only have a single-phase connection then under the current rules the installers are only allowed to install 6.6kW of solar with a 5kW inverter (unless you get a battery, then you can go up to 10kW).

Hope this helps
Jason

I have a single phase system Jason.

So the electricity infrastructure companies’ blunt instrument that Marty talked about is the issue.

That is just slightly daft, and so typical of Australia’s foot dragging/coal digging attitude. But then you get that when our leaders are actually followers. Reluctant followers at that. Grrr.

And had I known that I would have explored having three phase electricity installed last week when I had the meter box replaced and the circuit from the meter box to the connection point from the street upgraded from a 6mm wire to the current 15mm standard. Only for the L2 electrician to discover that from the house to the street pole is also only 6mm! Acceptable when the house was built in the mid-70s, but nowhere close to supplying all of the electrical appliances that we now all expect to have in our homes.

Is there no electronic gadget that I can strap to a system with 101 panels (!) that ensures that I only ever feed 5kW into the grid and keep them happy? That way I’d be getting maximum payback all day on my money instead of it stagnating in a bank.

BaDaHe
NSW South Coast

Again using your SOLAR SIMULATOR, the 6.6kW maximum allowed for a single phase system does give me the ability to create the maximum amount of power that could be fed into the grid, but only at midday when The Sun was having a good day.

The rest of the time I would not be coming close to hitting that 5kW limit. Unless I had more panels – that would enable me to get to their dictated limit far more, and therefore earn more.

To answer my own question, it seems that there is a way for me to be able to limit my export to the grid to just 5kW in my single phase house. See this article from three and a bit years ago: Solar unlimited: How to use inverters to get past export limits | RenewEconomy

Well it almost answers my question, except that I want to use micro inverters – so my question has become:
Is there an electronic gadget to limit to 5 kW my export of power to the grid in my single phase house with micro inverters installed?

BaDaHe
NSW South Coast

These export limiting devices have been around for a while @BaDaHe, and some distributors do allow them. More common these days is that the inverter itself will allow export limiting. Whether it’s a good idea for you to get a 10kW system for eg limited to 5kW export would depend on your usage. And whether you are allowed to depends on your distributor.

What is your distributor, or what is your location? And how much electricity do you use?

Cheers
Marty

Hi guys,
It;s been a while since i’ve contributed here. But in answer to your question. In WA grid sizing plays a big part, quite often we have to upgrade the feed line to accommodate the solar install. In more precise language you may have to upgrade your domestic feed from 10mm2 to 16mm2 to accommodate your solar. What most people don’t understand with solar, is “voltage rise” (your installing a power plant). If I was to run a 3hp pump out in a paddock and the run of cable was 750m I’d need some big ass cable due to voltage drop over distance. The reverse applies applies when your talking solar. You get a voltage rise. So the cable sizing matters, not only the feed to your property but the grid itself. This is the reason you can only have what they let you have. And still to this day we get “AC Voltage to high” faults regularly. In other words (and I deal with this alot) I install a system and it works fine for two or three years then someone up the road installs solar and there feed in back to grid forces grid voltage to rise to 270 volts (these are the spikes that blow up your new 75 inch Samsung etc). everything shuts down on a decent inverter or blows up on cheap crap. So what your facing is 1) your local area grid 2) your domestic feed line 3) Your retailer won’t pay you for export over 5kW inverter (in WA, they count battery inverter as well so we’re screwed for feed in tariff) ie’ Install a 5kW storedge “5kW solar inverter 5kW battery inverter” “your not getting feed in tariff”.
To sum up you, can have what you can have hardware wise, they don’t care to much as long as the grid can handle it, but anything over 5kW inverter will kill feed in tariff.

Kind Regards
Den Thomson
Downsouth Solar Power

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Sorry for the typo’s had a few :wink:

Oh I forgot to mention that they don’t accept zero feed in setting because, any tool with some knowledge can change that from there iphone. I need to cap this off by saying that the CEC will only pay STC’s up to 33% over inverter capacity which is why 6.65kW panels over 5kW inverter.

Great Topic!

I’m Not an electrician, but have given myself a few AC Zaps over the years. :cowboy_hat_face:

However, as for 10mm2 wiring, I assume you talking AC Wiring from the Power Box back to the State Grid ?

Interestingly, out at the end of a power line at our Remote/Heritage Property, there is only One Hi-tensile Steel Wire tightly strung between power poles. The Single strand Wire looked like 8guage Fencing wire, but specially made I suspect. Helicopters fly over the line a few times a year to search for Hotspots, I was told.

This single line supplied 240V to the homestead (240Vx15Amp = 3’600kWh Energy), I think there was Hi-voltage 480VAC Power Transformer across the Valley, like modern Distribution lines. As we ran 2.5kW Water heaters, Ovens & washing machines etc. The Power came in on a single line.

As 3hp is 2.2kW line Power, Can one run a Single Steel Cable for AC Power in conduit (or high to code power poles) & install a Earth Spike to code where the Pump is installed ?

As I am lead to believe, the higher the Voltage the smaller the mm2 wiring required, and think that goes for AC or DC Voltage, Yes ?

That should Tell Everyone to Purchase a Battery with a minimum 10kWh Energy (or at least a battery bank to supply 24hr consumption). Currently a 10kWh LiPO4 Energy storage is under $5’000 for a single unit or under $8’500 for two.

Then a System owners will be Energy Independent & could easily & simply Replace the State Grid with a cheap 3.5kw $900 fuel Gen-set that would rarely used other than extended bad weather, as most Off-Griders know !