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Solar energy systems in Australia and Netherlands

Identical here.
Unsurprising given:

Screen Shot 2024-02-12 at 10.53.44 am.png


Rooftop PV is still growing very strongly here. Capacity will double in the next decade or so. Eventually it will begin to level out as the number of available rooftops lessen. Currently 1/3 homes have solar PV.

The other aspect is we likely have a higher average yield from our PV given the more favourable latitudes.
 
I have a single-phase power system. 8.75 kW panels, 6 kW inverter restricted to 5 kW export, 15 kW batteries, vehicle power supply up to 7kW. I have a FIT of 11c / kWh. The system is now just over 12 months old. I have not paid a power bill or for any power to a MG4 77kWh BEV (except for travel over 250km from home, i.e. 500km round trip). I estimate I am saving $5,000-$6,000 a year on a $25,000 system. The only way I am aware of any blackouts is when the neighbours tell me.
 

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Since we're doing a show and tell, here is an old photo of my system. Sorry, it's a bit wet to take a new photo today.

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This is a penny pinching setup. The larger cells are from an EV kit that I bought cheap at an auction; the smaller cells are also ex-EV, from an accidental short circuit that rendered many cells unsuitable for EV use, yet are doing OK as part of the house battery. These cells date back to 2009, and have been used in this system since 2015.

The original 45 cells (144 V nominal) were split into 16 for a friend, and the remaining 29 were not quite enough for 16S2P. Hence the Frankenstein battery. One 160 Ah cell (the larger ones) is paired with two 100 Ah cells (the smaller ones), and there is also a "quad" (four 100 Ah cells in parallel). So it's really 14S2P + 3P + 4P, or if you count the 100 Ah cells as 60% the capacity of the 160 Ah, then it's 14S2P + 1S2.2P + 2.4P! In retrospect, I should have divided the cells into one 15S string (enough for a 48 V nominal system, like Pylontech and many others), and one 15S2P system. I have had replacement cells for years, I just need to find the time to install them. They are radically different in size (very tall), so I have to redo the shelving to accommodate them.

Note the pairs of 50 mm² cable to each bank of cells; this is necessary to satisfy the requirement that the battery cables can withstand a dead short (8 kA in this case) for 10 seconds without catching fire. These tired old cells could not put out a quarter of that current any more.

You can see strapping and threaded rods holding the cell groups together. This is something you have to do for prismatic cells, to stop them from swelling, even with no mishaps.

To the left of the photo you can see the edge of a large toolbox that used to house the lead acid battery that was this system's predecessor. That was a 24 V system. There are still cells in there (more 100 Ah cells), running a few lights for redundancy.

The white circles with two terminals are EV200 contactors, capable of 200 A DC at hundreds of volts. They were obtained cheap from Ebay, I suspect from failed EV or similar companies. Some were lightly used, others brand new. The Big Red Button at the left drops all the contactors, isolating the battery, inverter, and a smaller AC contactor drops the AC-in.

The Blue Sky box on the right has been replaced with a second 5 kVA 4 kW inverter. The two in parallel run all the house loads except for the oven (rarely used now that we have a convection microwave), water heater, and ducted air conditioning. I have mused about putting the water heater on this system, but when you need a lot of hot water (winter, rain), there isn't much solar power, so I don't bother. The inverters run fully patched firmware, which overcomes a number of limitations of these inverters when using an LFP battery.

The white boxes at the very top house the PV breakers. I now have 2S14P of panels (it's a low PV voltage system, unusual these days). All positions are full now. 5.65 kW nominal of panels. They are all tiny panels by today's standards; 195 W, 200 W, and 215 W. The 6 215 W panels are mounted at 45° inclination and are on top of the carport on the south side of the house. The 45° angle is to make these perform better in winter, when you need PV power the most.

There are two small computers there. One is a Beaglebone Black, like a Raspberry Pi but supposed to be better for the number of serial ports or some such. It handles monitoring, and networks to my laptop (Ethernet cable or WiFi). The other computer drives all the contactors and talks to the Cell Management Units, one is on top of each pair/group of cells. They communicate via industrial fibre (a cheap plastic based fibre suitable for short runs).

With the cover on, the case is featureless, and has the same proportionality as the monolith from Arthur C. Clarke's 2001: A Space Odyssey.
 
Unsurprising given:

View attachment 23857

Rooftop PV is still growing very strongly here. Capacity will double in the next decade or so. Eventually it will begin to level out as the number of available rooftops lessen. Currently 1/3 homes have solar PV.

The other aspect is we likely have a higher average yield from our PV given the more favourable latitudes.
The growth will come to a halt for sure. And it's precisely the reason you mentioned: lattitude. We cannot generate enough the whole year (assuming we could store) so we take from the net and deliver to the net. Up until now, you could take away the costs of power taken to as much as you could deliver (annually). This is being dropped. Since we only use 33% max of our solar directly, we will be delivering 67% solar for free to the electricity companies. No longer economically viable. The latter is of course denied by companies selling the panels, as well as by politicians stating the price of the panels have dropped. But nobody mentions the price of installation:that has increased. In fact, my 6 year old set of 15 panels is 1500 euros cheaper than a compatible set now.
The people are no longer blind though. They know the government reputation. So I predict a full collapse of the solar panel business.
For batteries we are stuck. Prices are extremely high.
 
Since we only use 33% max of our solar directly, we will be delivering 67% solar for free to the electricity companies.
Over the last four quarters, we have self-consumed this proportion of our solar PV output:

Q2 2023 68.3%
Q3 2023 58.1%
Q4 2023 70.9%
Q1 2024 89.6% (to date)


Lots of strategic load control helps. Maximises the value of our PV system.
 
Over the last four quarters, we have self-consumed this proportion of our solar PV output:

Q2 2023 68.3%
Q3 2023 58.1%
Q4 2023 70.9%
Q1 2024 89.6% (to date)


Lots of strategic load control helps. Maximises the value of our PV system.
Do you happen to use air conditioners a lot (cooling and heating)?
 
Do you happen to use air conditioners a lot (cooling and heating)?
Yes, especially in our Summer months, it's not just hot but very humid. Aircon is rarely needed in Spring/Autumn, while a little is needed for heating in Winter.

Since 1 January our total aircon energy consumption has averaged 40 kWh/day. That's for two dwellings and one occasionally used outbuilding.

A bad day can have >100 kWh of aircon consumption. Usually when we have a friends/family visiting on hot/humid days. Our main home is thermally challenged. Been making improvements but it's a losing battle at times. The vaulted ceilings with limited insulation and the 80+ m² of single pane glass make life difficult. The second dwelling is much smaller and well insulated and as a result uses a small fraction of the cooling energy we do.
 
Yes, especially in our Summer months, it's not just hot but very humid. Aircon is rarely needed in Spring/Autumn, while a little is needed for heating in Winter.

Since 1 January our total aircon energy consumption has averaged 40 kWh/day. That's for two dwellings and one occasionally used outbuilding.

A bad day can have >100 kWh of aircon consumption. Usually when we have a friends/family visiting on hot/humid days. Our main home is thermally challenged. Been making improvements but it's a losing battle at times. The vaulted ceilings with limited insulation and the 80+ m² of single pane glass make life difficult. The second dwelling is much smaller and well insulated and as a result uses a small fraction of the cooling energy we do.
Thanks!
With that much energy for aircons per day it truly must be hot and humid.
 
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With the cover on, the case is featureless, and has the same proportionality as the monolith from Arthur C. Clarke's 2001: A Space Odyssey.
Cool!

Yeah you are making the most of whatever you could lay your hands on. When I first looked at the battery I was confused about the set up. After reading about it I think I'm more confused :LOL: .

14S ~= 45 V

I see even pre-made batteries are getting quite "affordable". Goebel Power have a 280 Ah 51.2 V unit at A$224/kWh. Complete with 200 A BMS, battery balancer, terminals, big DC breaker, on/off button and display panel. Need to add shipping cost to that but even so, it's pretty decent value. Uses same brand BMS my existing units do.
 
That's good. Does it allow you to download your interval data? Their website is a bit skinny on their service.


Total.


The issues in some areas is too much solar PV.

The state of South Australia is our "canary in the coal mine" having to implement a range of strategies (70% of their energy is from wind and solar PV and at times 100% of their state demand is being met by rooftop PV alone).

What they are now doing is requiring new PV inverters be network connected so they can be controlled by the system operator, with exports and/or production ramped down when needed.

The quid pro quo is they are approving larger inverters and higher export limits and this is favourable most of the time (e.g. Winter, cloudy days) while the only time output is curtailed is when the grid is well oversupplied.

They've also installed more grid scale batteries and syncons to help with grid stability and to reduce reliance on gas peakers for this job. A new HV interconnector is also being put in to neighbouring state of NSW which also helps spread the capacity.
The app has a histogram and scrolling through it, displays the kWh used and the solar credit for each 1/2 hourly/Daily/monthly or bill cycle period as selected. I can only download the data for a bill period (3months) or for the last 12 or 24 months
 
After reading about it I think I'm more confused :LOL: .

14S ~= 45 V
Yes, it's a mess. It's 14S of "normal" 2P cells all the same capacity. But in total, it's 16S, with one "hybrid" cell (160 Ah in parallel with two 100 Ah cells), and one "quad" (four 100 Ah cells in series). The idea was that the higher capacity "cells" would never get empty, yet they would still top balance. In reality, I never know what the true state of charge is.

It will be so good to get the newer cells in, at least they are all the same nominal capacity. Sadly, being second hand also, some of them have higher self discharge than others, and I've already lost several years of "shelf life".
 
My last bill with Red Energy was $308.00 after a $125.00 cost of living rebate credit was applied. This was on my old tariff and before the extra 6.6kW of panels were installed. I was charging the MG on off peak at this stage.

The app has a projected charges graph based on what has been happening. The next bill is due on 8th of March so from 9 December to the 7th of February will be without the 6.6 kW system.

On Sunday it was cloudy and the 6.6 system produced 26.6kWh for the day plus the old 2kW system produced a guestimate of 6.5kWh so I'll round this to 33kWh for the day.

I did my monthly 100% charge starting at 9:50am and consumed 42.5kWh finishing at 4:35pm. I get 2 hours free from 12 till 2 so after using the solar & free 2 hours I used 13.4kWh from the grid so the cost including GST is $3.61 for 42.5kWh or 8 cents/kWh. The charger was operating at the full 32 amps the whole time.

I'll adjust the input amperage to suit the weather from now on. I can reduce this by 1 amp intervals on the EVSE app as required to suit the season & weather with a view to using solar only. I do not have any intelligent software installed to do this so it will be an educated guess.
 
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Yes, it's a mess. It's 14S of "normal" 2P cells all the same capacity. But in total, it's 16S, with one "hybrid" cell (160 Ah in parallel with two 100 Ah cells), and one "quad" (four 100 Ah cells in series)
Ah, so the whole case is one x 16S (51.2 V) battery bank but the individual "cell groups" are made up of various cells in parallel depending on the cell(s) used.

I'm actually pretty amazed at just how robust LiFePO₄ is. It seems to tolerate all sorts of Frankenstein set ups and just work. Maybe not perfectly/optimally but good enough to be productive / useful.
 
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