TimCam

Thanks everyone. This is the route I am going to go

Good afternoon.
I have a lady who has worked for us for many years. We are moving to a retirement centre and she has decided to go "back home" to the Eastern Cape. In the village she is in, there is a community borehole with a 5000L tank on a small stand and a solar borehole water pump. And that is it.
She wants electric lights and possibly a TV. Please advise what would be needed solar wise (panel; battery; inverter, and MPPT) for the following.
12 LED 7 watt 220V globes of which only 7 would be on for an average of 6 hours per day.
A LED TV of 100watts 220V that would be uses on average 3 hours per night, but possibly another 3 hours during the day.. No other electrical appliances expect cell phone charging
I want an inverter as 7W LED 220volt globes are cheap and available everywhere, whereas 12V LED globes are expensive and difficult to come by.. If the use of the TV requires the use of a massive battery please do two specs, 1 with and 1 without a TV. I want an overkill on the solar panel, they are cheap, and I want to compensate for cloudy days.
thanks

And of course to have all this working reliably, you need reliable electricity. Which is why this forum is here.

Yip, and as an installer who has to maintain legal requirement and warranties, it's best to follow the manufacturer's spec sheets.
But for the private households who are willing to push the envelope a bit.... 🤔

Actually, an inverter can rely on the speed of the CPU to limit the PV current on the fly only if there's enough margin between "power capping" level and actual limits of the inductors and silicon used in the MPPT. For example, many Victron's MPPT chargers are designed for 70A of PV current, while their "power capping" happens way before that limit. Therefore, it's safe to put many more panels on them.
SolarEdge (ongrid inverters) have a similar feature - their MPPTs are designed to safely cap 30% of power (and current) that is above rated power of the inverter.
Old standalone MPPTs that were designed for charging lead-acid batteries were able to avoid overcurrent issues too, because lead-acid batteries don't like to accept charge when the SOC is high (contrary to lithium which sucks any amount of current supplied, although being at 99% SOC). And when there's nobody to suck the excessive current from the battery-side of the MPPT, then there's no way for current to appear on the PV-side of the MPPT. (I saw guys having like 12kW of PV modules on a 4kW MPPT, just to survive EU winter)
Speaking of Deye, SunSunk, JASolar and other rebrands - base of the firmware is identical, casing and topology too. But each large-scale OEM customer of Deye can alter some of the parameter based on the target market. Including logo, quality of selected components and FW limits. For example, there are Deye models with MPPT designed for 2x 26A and others designed for 2x 50A, while the rated AC output is the same.

Long-story-short, as a technician I always try to follow the manufacturer's spec sheets when designing a system.

My old SunSynk 8.8kW machine just clips the current without any issues or error messages. Notice the date, and all is still fine.
I have now connected 13.1 kWp in the last month or so, and am looking forward to getting through rain and cloudy days this summer.

I know of a Sunsynk that ran for a couple of months on the PV current limit. The installer was supposed to pull in two channels but paralleled the strings. The inverter is still running.

@Scorp007 & @tsf The inverter is a 3960W inverter, it doesn't matter how many panels you have on it it is not capable of generating more than 3960W of AC power.
The only time it would be able to generate/utilise more than 3960W of power would be if it is charging a battery with the extra DC power.
As I said, the reason for allowing more panels is so that you can still make decent power on low solar radiation days.
Keith from Sunsynk has a pretty good video explaining the reasons for over watting your inverter

Supplier admitted he had 2 that seemed to be faulty, refunded me, thank you.

Nope, the "state"is a burden to the public, due to their incompetence, theft, bloated and unnecessary departments, insane salaries, thousands of unnecessary taxes, etc.
Now these government muppets are trying new and expanded ways to steal more money for themselves and their cadre's.
All of this has absolutely no benefit for the public or local businesses. Obviously I'm not a fan of bloated governments... 😒

Nope, the "state"is a burden to the public, due to their incompetence, theft, bloated and unnecessary departments, insane salaries, thousands of unnecessary taxes, etc.
Now these government muppets are trying new and expanded ways to steal more money for themselves and their cadre's.
All of this has absolutely no benefit for the public or local businesses. Obviously I'm not a fan of bloated governments... 😒

Nope, the "state"is a burden to the public, due to their incompetence, theft, bloated and unnecessary departments, insane salaries, thousands of unnecessary taxes, etc.
Now these government muppets are trying new and expanded ways to steal more money for themselves and their cadre's.
All of this has absolutely no benefit for the public or local businesses. Obviously I'm not a fan of bloated governments... 😒

Nope, the "state"is a burden to the public, due to their incompetence, theft, bloated and unnecessary departments, insane salaries, thousands of unnecessary taxes, etc.
Now these government muppets are trying new and expanded ways to steal more money for themselves and their cadre's.
All of this has absolutely no benefit for the public or local businesses. Obviously I'm not a fan of bloated governments... 😒

Some of the rumors I've heard floating about are that some large solar installations were affected by weather (wind, cloud, dust, not sure?), and caused large fluctuations in output. This would support your thought of renewables with insufficient battery reserves.
With load 'constant' and generation diminished and not sufficient battery reserve, frequency would drop below 47.5 Hz, and other generation plants would disconnect away from the transmission lines causing a cascade.

Please tell me that you are joking.
If not, do you really think that it is a good idea to pollute this forum with far-right political conspiracy theories?

Meanwhile in South Africa: https://www.eskom.co.za/wp-content/uploads/2024/12/Eskom-integrated-report-2024.pdf
Eskom is doing less with more money and people.
A blackout in South Africa will take 14 to 21 days to restore... perhaps we should rename "doomsday-prepping" to "Eskom-proofing".

Exactly under the banner of maintenance instead of load shedding as of late who will notice " not the public that payes for it all" millions of litres in diesel thanks to OCGT Ankerlig ect.......

Whilst I tend to not have much nice to say about eskom, I doubt we will se total blackout.
I believe at this point they have mastered how to do rolling area blackouts to mitigate nationwide blackouts.

I'd like to add that some not very reputable sources have been blaming Greta Thunberg. But she was 3 years old when the 2006 outage happened, and so she is not the only possible cause of a large scale grid outage.

If one has enough storage or load during the day the north still gives a much higher yield as you suggested. 😀

Deye and SunSynk are both excellent pieces of hardware, differentiated by branding and firmware. I personally enjoy the SunSynk firmware, but that is personal taste.
The failure rate has been quotes at 0.4% for SunSynk, but with a large installed base this reflects as "more" failures than other brands.
I have had my SunSynk 8.8 kW machine for a number of years now, and have never had it fail unexpectedly.
Once it did shut-down, but the reason was expected, and no damage to the inverter or household appliances.
What happened is there was a municipal Neutral failure which caused over 300V between Live and Earth, I have SPD's on AC incoming and Essential Load after the inverter.
The SPD on Essential Load fired and shorted to Earth, which caused the inverter to shut-down.
Walking into the power room and smelling that acrid electrical burnt smell sends shivers down the spine. 😕
Once the fault was diagnosed, municipal power was disconnected, the damaged SPD replaced, the inverter booted up with no problem and ran on batteries for the night.
One tough "sun of a gun", so I am happy with my machine. Also I have passed through well over 10 kW.

Hi
Recently after having a power failure with being rainy and overcast the previous day, I woke up to find my house without power despite having an 8Kw Sunsynk inverter with 500ah batteries.  It was 5:30 am so I took my torch and investigated only to find I had completely depleted my batteries.
I had recently coupled my geyser to the grid from gas as I had added more PV panels and had ample power (9000w) to use. I also have to power a borehole pump and aux pump from the JoJo tank.
I have a 6Kw petrol generator coupled to the inverter which can be switched to the grid or aux (gen) input without an auto-start. I proceeded to start the generator and switched the generator to the grid input, only to find that this did not work. I was very annoyed and then switched over to the aux (gen) input to find that this also did not work.
I thought I had it all sorted when I installed my system and bragged about my installation, however to my regret, I got a wake-up call.
After checking the generator voltage indicator, I saw it did not show any voltage. I was convinced that this was a generator fault and did not try to put the generator in the bypass mode. I proceeded to switch all the large loads off (borehole pump, switch the geyser to gas, and only use the gas hob). After taking my grandchildren to school the sun was up and my PV panels did power the house to my relief and not to get an earful from my wife.
After getting help (4 guys) to remove the generator (100kg) from its bricked housing I started my fault-finding. To my surprise, only the mechanical voltmeter was broken.
 What now as it was not the generator?
I took the time to clean the generator and put it back in place with help. I did all the switchovers again only to find it still did not work.
Just to mention that I have spent more than 40 years working with electronics and instrumentation.
One of the most important things I have learned over the years is to go back to read and follow the instructions. 
This is what I did. I also followed up with videos from Sunsynk and this was the result.
1.       The biggest problem was the frequency which was 54.6 hz.  I had to adjust the frequency on the generator under load as close to 50hz as possible. This can be done by adjusting the screw on the linkage arm of the carburetor which will correct the speed and frequency.
2.       The frequency band on the inverter also needed to be adjusted for a larger band to accommodate the frequent load changes of the generator.
3.       There are other settings as well that affect the inverter if the generator is grid-coupled or aux-coupled. It also matters if you use timed settings as this will override the start and stop charging settings of the battery. The grid-tied generator to the inverter is much less forgiving to frequency change.
4.       The charging of the batteries from the generator needs to be set lower on a grid-tied generator.  if you set it too high there will be no power for the household load. The best Installation is to have a generator twice the power of the inverter so that it can charge the batteries without affecting the load. This is always not possible so be sure you have adjusted the settings for the size of the generator.
5.       If you have an electrician do the installation, make sure that he has done all the checks and has tested it before it is signed off. It will always be up to the owner to read the instructions so you can be sure the electrician has done all the tests and correct settings or else when the generator is needed it might fail and you might need to pay again to have it set correctly.
6.       Finally, the earthing of the generator.
A.      If it is coupled in the grid mode, the neutral has to be coupled to the earth as there is no link to neutral for a series earth leakage (RCD) to work if the mains neutral is decoupled.
B.      When the generator is coupled to the aux (gen) input the inverter should already have an earth bond relay installed to protect the system with the earth leakage (RCD) in series when the neutral is decoupled from the mains in the inverter during a power failure. I use an automotive 12vdc relay which can handle 30a.
In a complete circuit, there must only be one earth-neutral bond.
I see many installers fitting a permanent bond between earth and neutral on the inverter. This is illegal as now there are two earth-neural bonds when the mains power is present. (one in the inverter and one in the DB. Box).
I find it pure laziness that an electrician cannot use a relay to couple the neutral to earth even if the inverter does not provide a signal or voltage output as he can use the 220vac mains power input to the inverter as the signal to connect the bond.
NB: THE earth-neural bond must be the bond of the neutral on the output of the inverter to earth and not the neutral input from the Mains Power input.
 
The earth-neutral bond done on the Mains input is only done when the Mains Power is disconnected (live and neutral) and a Generator is used as the Mains Power input.
All is now good and working as it should.
I hope this will help someone who wants to couple a generator to an inverter and avoid the same problems and frustrations I have gone through.

Yes, my insurance covers the damage. I did the install in 2023 and it was running clockwork till the heavens decided otherwise. PITA to remove the batteries and inverter for repairs but I took the inverter out today - will take it to Sunsynk in the morning. It seems the comms are not working. I will report back. I am learning a lot through this exercise.

I agree with you 100% and that is what I am going to do.

90mV can easily happen while the battery is charging or discharging. Having current in and out makes the delta quite a bit higher.