HennieL

Not sure of your model, but my 12kW Sunsynk inverter has a 12V connection (Pins 11 and 12) that should be just what you need - just confirm in your user/installation manual...
See screenshot from my manual below. Hope this helps 🙂

Not sure of your model, but my 12kW Sunsynk inverter has a 12V connection (Pins 11 and 12) that should be just what you need - just confirm in your user/installation manual...
See screenshot from my manual below. Hope this helps 🙂

Actually I have never thought of checking the other terminals for output voltage.
I have 5.5k sunsynk similar to the @WelshDragon80 image.
I am off to find my multi-meter and go check :)

Agreed with @TaliaB .
The secret to a long RO membrane life is to:
Regularly replace the sediment pre-filters
Most importantly, regularly replace the activated carbon pre-filter. This removes the chlorine in the water (chlorine actively damages the membrane and can ruin a membrane in a very short time - days, not months, if present in the water in measurable quantities).
Ideally the membrane holder should also be flushed with "bypass" flow to actively flush away any mud/sediment that accumulates in this housing and around the membrane. It's normally a good idea to flush the membrane at least twice during the interval between replacement of the pre-filters.
I would not fret about the "good elements" stripped from the water by the RO - I have been using RO water for many years, with no detrimental effect, but the post filtration mineralization cartridge does improve the taste of the water.

Yes this is latest Home Assistant on RPi5 with nvme drive to make it nice and quick and to handle the sheer volume of live data, this is the latest version of my layouts with multiple tabs to access all the data and settings for the batteries and inverter all on a single dashboard.
No more running to the garage to check and adjust settings :)

Battery Screen.


Power Charts


Battery Settings - not all added yet.

I have quite successfully "stored" 1200 litres of water in a plastic Eco tank over a period of nearly three years, by continuously using a small amount of water from the tank and replenishing the used water with fresh water from the municipal supply. I connected the tank through a pressure pump to our kitchen tap, an RO filter, and to the washing machine, in total using approximately 20-40l of water per day. This small amount of municipal chlorinated replacement water has managed to keep the total 1200 litres in the tank clean/fresh enough to use for washing dishes and clothes, and after filtration through the RO filter for all our drinking and cooking water. The rest of the house is still fed directly from the municipal supply. Over this period we have had a number of "water sheddings" lasting from hours to 3-4 days, and during those periods the stored water in this tank was used to also supply water to the bathrooms and geyser, and to flush the toilets. I'm happy to state that we survived even the longest of these shutdowns with water to spare.
Although the stored water is still quite clear, and odor free, the bottom of the tank has accumulated a thin layer of sediment deposited by our rather muddy municipal water, and I would not classify it as fit for drinking without filtration The RO filter really does an excellent job of filtering this water and not only making it fit for human consumption, but also for making exceptionally tasty coffee and tea - the only down side being that one wastes about 75% of the water that's filtered.
Hope this is of some use 😊

Yes, that would be the simplest, and best (IMHO) solution. One can choose to boost a car's engine to deliver nearly double the horsepower it was designed for, but then the engine just won't last. Even without modifying the engine, it would still not last very long if you continuously kept the revs on the red line - I know... did just that in my younger days with an old motorbike after drinking too much rum 🫠☠️
So, throttle back on your power export when conditions require, and your inverters will last much longer.

@bobah1248 I hear you... but look at it from another angle - you just want to keep the inverters from throttling down, thus keep their power elements below about 60-65 degrees C. If they are currently heating up to 70-75 degrees C during the day, then you just need to cool them down by 10-15 degrees, and the current cooling down systems (heat sinks, built-in fans, additional fans, etc. etc. should take care of the rest.
Have a look at this thread: https://powerforum.co.za/topic/29611-cooling-sunsynk-5kw/

I'm currently involved in an upgrade of a solar farm in La Réunion and a bit pressed for time, but I’ll circle back soon with some insights and a matrix comparing price vs quality vs ROI, using a key metric for fair comparison."

Perhaps you should start the ball rolling by explaining what a transwall is, and the principles that would make it work - the old Transvaal worked very well, but I'm sure that's not what you have in mind 😄

Thanks for your detailed, and well thought-out and articulated response - and I agree that there are some very good (ethics and value wise...) installers, but the problem arise when an inexperienced new PV owner-to-be decides to bite the bullet and install "some solar".
When I installed my first inverter (for myself) way before Loadshedding was even a word (around 2007 if I remember correctly...) there was very little information available on designing a system, and on available components. I basically had to bite the bullet and chose my inverter just based on country of manufacture (a Swiss made Studer XPC 2200-24...). Even in those days the batteries were ridiculously expensive, and I had to settle for 4x 12V telecoms type deep cycle VRLA sealed units that were made in China (and that lasted a good 16 years, I'm happy to say...). Although I did do my homework as best I could, given the scarcity of any decent reviews and data, it was still a gamble. Solar panels in South Africa were as scarce as chicken teeth, and I thus just used my system as a backup for some critical equipment that I wanted to always have power, fed from a rather reliable grid...
I designed my current system myself, based on what I learned through my trial and error first system, and after having done a lot of online research over a period of a few years, and only once prices dropped to more reasonable levels after Escom managed to eliminate most load shedding (mid 2024...). I thus specified the equipment to be quoted on, and the installation was done by a licensed electrician that came highly recommended by some happy clients that I know very well. Even so, to this day I don't know if my choice of equipment was the best "bang for the buck", or if the installation could perhaps have been done better - after some 10 months everything is still working as expected, but 10 months is a very short time in the life of a PV system...
So, from personal experience, I would have been much happier if I had access to unbiased feedback from experienced people on a Forum such as this, and I am still of the opinion that a "quality vs price" matrix of equipment would be of value to the majority of people just starting on their journey into solar.

The guy is really talking about what I understand to be a grid-tied system - inverter & panels but no battery. Batteries significantly change the ROI. Maybe such systems are becoming more popular in SA now that the likelihood of load shedding is so reduced. IDK. I bought a system with a battery, and the battery is the most expensive part of the system.
He makes another good point: The economic worth of the system to you depends on the price of electricity where you live. IDK what Eskom tariffs look like, but here in Johannesburg the default post-paid tariff carries fixed fees of just over a grand a month for a 60A single phase feed. You are in for a grand before you use a single kWh of electricity. But we pay less per kWh than folks in Cape Town do. So there is some maths for the purchaser to do.

And this is where a good installer comes in. A good installer will discuss your desired outcome, understand your current situation, guide you as regards likely savings. As in so many business areas, there is the bakkie brigade. They will quote a low price, slap some panels on your roof and an inverter in a corner. And that's it. The job may or may not meet safety requirements (that is to say it may or may not be legal) and should you want support after the install they will be unwilling and/or unable to provide that. (I have seen several properties in my neighbourhood with South facing panels - I find it hard to believe that those installers were doing the best for their client).

Other installers will take the time I already mentioned, will stay in touch with you for a while and monitor your system.

Then you have the rental companies who are attractive to the people who don't want to lay out a large wedge of cash and who don't walk to discuss technicalities. Those guys are not my cup of tea, but they are attractive to some.

A thing I notice in my neighbourhood is a change in conversation. A year ago it was that they could make me register my system after I've run out of ammunition. Now suddenly people are wanting to register. IDK why, my system was registered last year. So now the quality of the installation is done and really we should be doing what COCT enforces - you register first, then you install.

This is all about the installer, but an installer with skills and knowledge and paper work (can sign a COC, can do the registration or has access to somebody who can) is worth something and so is their time.

So for me this is like buying a "1600 cc car". Well there's whatever is the cheapest on the market right now, and there's the BMW and the AUDI. There's what is going to look flash in your driveway, and there's what is going to give you years of service - they may be the same, but it's not guaranteed and if you buy on price then you will get one (more likely the first) or the other but not both.

Too many variables beyond the price of the component.

I thought the guys who installed my system were good, and to be fair they provided support three or four years down the line.

Then I thought the guy who did my registration with the City was good.

Then I found out that my panels were not earthed - despite this being shown on the drawing submitted to the City. So my system was never compliant - despite the registration that was obtained.

The cost of a good system is more than the cost of the components.

To return to my opening point. I bought my system at a time when load shedding was on the rise - though not as bad as it would get. I work from home. We buy food in bulk and fill the deep freeze. We sailed through stage 6 with no hiccups. That's worth something too. I can't put a rands and cents value on it, but it has value. By one set of calculations I still have not recovered the cost of my system (we were not using a lot of electricity even before we went solar, because we are careful) but factor in those soft values (which may not apply any more) and there is working from home V commuting every day. Or working from home V the cost of a trolley inverter and new batteries every two years. No, I can't work it out either. My point is that the ROI proposition has changed and so the type of system we buy might have changed.

So I think there's no template/matrix to be drawn up. Every client has different expectations, and the installer makes a difference. There are some installers who use this forum who, and I have some personal experience in this regard, provide a very complete service. You have other guys who will wait until the money has cleared their bank account, slap some equipment around your house and disappear. You will have DIYers.

I met one of the latter who told me the cost of going off grid was 40 grand. He bought bits and piece from Builders and did it all himself. Who knows what he has and how good a job it does and if it is legal. And who knows whether or not he would have done better if he'd got somebody with a clue to provide a system for him.

TLDR. I don't think it's just about the cost and quality of the components.

The trajectory of this discussion is very much welcome, in my view and makes sense especially given there's experts here who know how to calculate all if not most of the variables and also we have people who have "real-world" experiences of what was put on paper vs what they received and what they are experiencing in both the short term and long term. As someone who in my initial dive into Solar was absolutely reliant on installers and was willing to pay top-dollar, I still got my fingers and whole hand and body burnt and taken for a ride.
Now with experience am always willing to learn and also share my 2-cents. Installers who "supply and fix/fit" are also in this trade for making a living and making money and some are quite unscrupulous and this forum is a great help in correcting misconceptions and flagging also fly-by-night thieves. So am all for this idea of sharing, bantering, learning and re-learning.

My thoughts about it is: Get off grid and forget about exporting. Install an extra air conditioner in the inverter room. That would comfort the inverters and potentially extend their life. It would consume part of the produced energy but according to your writing anyhow overflows.

Dennis, are you a bot or something?
Just curious that you spew out single disjointed lines of text with little or no proper use of grammar or writing style.
Just Curious this side...
🤣

I don't quite understand your logic. Voltage is the same in every language and the only information that does not lie. That's the reason why all inverters are programmed to manage charging on the base of battery voltage.
No, that's not the way it works. The BMS cannot regulate anything, it can only cut off the battery in case certain limits are exceeded. If the parameters are set correctly in the inverter there will never be over-voltage as long as there is no failure.

Well, for one thing, I already extract about 2kWh from the batteries every morning before sunrise to heat the geyser. Discharging more than this some 2-3 hours before charging can begin via PV panels would drain the batteries further than I would like, so that's not an option.
Even though discharging may be possible down to -20 degrees C, it does not mean that it would be good for the batteries - after all, power is supplied as a result of a chemical reaction, and as most people would know, chemical reactions happen better/easier/quicker at optimum temperatures - which for LiFePO4 happen to be quite a bit higher than your quoted -20 degrees C... so discharging might be "possible", but arguably not "fine".
Anyway, I prefer to do things as best I can, and that's my choice - further CONSTRUCTIVE feedback is still welcomed...

That's a handy app to have. Been using it daily since September 2024.

https://en.tutiempo.net/solar-radiation/johannesburg.html

What is obviously correct cannot be disproved. Your calculation is spot on. (or I want a refund for my engineering degree...)
So, to replace my current 28kWh battery storage, I just need to build a tower 10000m high that can carry a 1000kg mass. Or 1000m high to carry 10000kg mass. Obviously cheaper than the R65k that 2 Dyness Powerbricks will set you back.🤣
LWT energy storage may have some application on industrial scale (e.g. using disused mine shafts) but for residential use it ranks up there with the horse-drawn zeppelin.

Just to elaborate further regarding the "fine" temperature ranges for LiFePO4 batteries - Summarized by my good friend ChatGPT:
True Electrochemical Optimum for LiFePO₄
Based on lab-tested data and peer-reviewed sources:
Parameter
Optimal Range
Notes
Charge Efficiency
15°C – 25°C
Peak coulombic and energy efficiency
Discharge Efficiency
10°C – 30°C
Capacity is near-maximal with low resistance
Degradation Minimization
15°C – 25°C
Lower electrolyte oxidation, minimal lithium plating
Internal Resistance (Low)
20°C – 25°C
IR is lowest in this band
Supporting Technical Sources
LiFePO₄ Cell Behavior at Different Temperatures – Detchko Pavlov et al.
“Degradation Mechanisms in LFP Batteries” – Journal of Power Sources (Elsevier, 2017)
Battery University & Victron Energy (practical integration guides)
EVE 280Ah LFP Cell Datasheet (widely used in Sunsynk and similar packs)

Living in the Free State (RSA), we regularly experience sub-zero temperatures over night during the winter. It is known that lithium batteries do not perform well when cold, and can be damaged if charged when below freezing temperature. My inverter and 2 x 10kWh LiFePO4 batteries are housed in my unheated garage, and I've been quite concerned that the batteries could become too cold to operate optimally. After some trawling of the internet, I concluded that it would be best to isolate them in a "box" of polystyrene sheeting, and to add two small (7W each) heating mats below the batteries to add a small amount of heat to this "box".
I initially used some duct tape to just stick the panels together as a "proof of concept" pilot project, and then added the heating pads, purchased from a local pet shop (sold as reptile heating pads...) after the first week of operation. After a second week of careful monitoring, being concerned now to not over-heat the batteries, I proceeded to properly build a box using 2x25mm thick polystyrene sheets as walls, and an insulating "floor" made from fibre-cement ceiling board mounted on a 6mm plywood sheet, and raised off the concrete floor with some 38mm x 38mm pine brandering for the two heating pads (placed in shallow wooden boxes and covered with a thick layer of kitty litter to act as a thermal mass below the batteries).
Here are some photos.
The un-insulated batteries, showing the insulating "floor" and heating pad boxes with kitty litter...

The duct taped temporary box...

...And the final enclosure before final fixing to the wall

So far, temperature variation during the last week ranged from about 14 degrees C minimum to 17 degrees C maximum, even though we experienced a few nights of zero degree C minimum air temperatures in the early mornings. We expect some typical -4 to -6 C lows in the next week or two, and I will report back on performance after the next cold fronts.
I am quite pleased with the outcome of this little project.
Your feedback, comments, and constructive criticism will be appreciated.

@TimG I do think your solar output for this time of year is inline with the low sun trajectory as winter solstice was the 21st of June where solar radiation is at it lowest and as @HennieL mentioned in real world conditions you will hardly ever see rated capacity.
For your inverter Mecer SOL-I-AX-5P your solar array is correctly configured(4P2S) as this inverter model has a low voltage mppt dc input range 60v~ 120v with max solar battery charge current of 80A so 4360w x 0.8/48v = 72.6A below the 80A mppt spesification.

Just a very rough estimate for Gauteng. Currently the irradiation is lower than in summer. I guess one would only see 75% of the rated value of the panels. This would be around 3.2kW if you have enough load connected and the battery needs some charging. This will be dependent on your charge amp setting/load switched on. Then the 21 degrees in winter will also negatively affect the production. If the panels were at 35+ degrees the output will be quite a bit more.

Henk,
You don't mention the inverter model, but a quick check on Microcare's website shows that they have 1, 2, or 3 kW bi-directional inverters than run off 12V, 24V or 36V batteries. The website also state:
"Built in, high rate, two-stage battery charger
Li-Ion Compatible"
This implies to me that these inverters were designed to be run off lead acid batteries, but that they are also compatible with lithium ion batteries.
Their user manual also has a wiring diagram for connecting to a Freedom Won battery with BMS (i.e. a li-Ion battery...). You will have to confirm if they sell 36V Li-Ion batteries, and if your inverter is modern enough to communicate with the battery's BMS.