Charl_CCU

Hi everyone,
I've had a grid-tie solar PV system for almost 30 months now. Recently, I've revisited the idea of going "off-grid" and only using Eskom when absolutely necessary and then disconnecting once Eskom/Tshwane starts implementing kWp limits or capacity charges.
To accompany this, I feel a solar geyser is a no-brainer. Any input would be greatly appreciated. From what I've read on the forum, it seems like there isn't a "best" solution and that there are a lot of "it depends..." My experience is that I feel that there are just so many different approaches and everyone has a different opinion on what is best.
1. Evacuated tubes or flat-plate collectors?
From what I've seen in person in my area, it seems like flat-plate collectors are a lot more popular. Is durability/quality an issue with EV tubes? If not, it seems like there is no disadvantage to using them besides upfront cost. Will there be a performance difference in my scenario? Is there a big difference between high-pressure and direct flow EV tubes? I believe that is the correct terminology?
2. Indirect or direct?
KwikSol/Sustainable claims that their indirect systems should be used "where the ambient temperature falls below 5°C and where the water quality is poor (more than 600ppm Total Dissolved Solids / Minerals)". Tshwane claims their water is soft at 80-100ppm.  Suntank states that in Pretoria Indirect systems should definitely be used.
What sort of maintenance and reliability can I realistically expect with either setup? For indirect systems, I've seen the mention of having to replace the glycol every 3-5 years. If it means the solar system isn't getting fouled up, indirect seems like a big benefit and especially with direct flow collectors.
3. How many geysers, which size and in which arrangement?
At the moment I have 3 x 150L geysers which have been kept in the same setup since I moved in. They've been replaced as they burst. Geyser 1 (G1) is located centrally to the house mounted outdoor in a ground-level enclosure against the exterior wall of the kitchen. All hot-water consumption points are within 15m at the most. G2 is located at the edge of the house and provides water for one bathroom. G3 is used for the domestic worker's shower which I plan on replacing with a gas geyser.
Is there any reason (barring piping issues) a single 300L geyser shouldn't be used to replace G1 and G2 and installed at the location of G1? I understand that it means a lot more energy is necessary to heat the water up when using an electrical element but it also means I shouldn't have any capacity issues? With the current setup of running the geysers on a timer with the PV system, supply is no regularly an issue except for when guests stay over. In that case G2 has plenty of hot water but G1 must be run on non-solar time to keep up with the demand.
It seems like putting 2 geysers in series is a popular option? I don't quite understand (and I would appreciate it if someone could help with that) it unless rarely need more than 1 geyser full of hot water. Why not just one big geyser with twice the collectors?
It seems like having one big geyser would be a benefit from a heat loss point of view as per @plonkster's post but it also seems like all the manufacturers I've looked at keep their diameter the same across all models and just extend the length.
4. Thermosyphon or pumped?
I think it is unlikely that my corrugated-iron roof will be able to support a large solar geyser with its collectors but in the scenario where a professional is able to determine that it is a safe option, is it specifically advised that I should or shouldn't make use of a thermosyphon setup? How reliable are the 12v Geyserwise pumps when used in a pumped system? I've seen a lot of complaints about it online, especially with direct systems.
What sort of maintenance and reliability can I realistically expect with either setup?
5. For EV tubes and direct/indirect geysers, which brands are known for their quality and performance?
Solar Ray seems like a good option for an EV tube setup. They only manufacture geysers up to 200lt for both integrated and non-integrated EV tubes so (unless you guys suggest a series setup) I would only be able to make use of their manifold collector. They provide a 10 year warranty. I'm not sure if that's only on the collectors or if it also includes their geysers. Solar Ray sells their 200lt 25-tube unit for R12.3k excl.
Suntank seems like a good option for the geyser and flat-plate collector as they also provide a 10-year warranty. Again, I'm not sure of the specifics.
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Unless you guys suggest there is a better approach (such as purchasing the parts myself and getting a plumber to install it), I plan on getting a professional to quote and install the system. The reason I'm asking for everyone's input is that, from my research, I've gotten the impression that a lot of installers have their preferred setup/brand which isn't necessarily what I would have wanted to go with if I didn't know any better. I made that mistake with my PV system.

Trust me: sooner or later the Axpert will blow up in this daisy-chained setup.
If you like to play with expensive toys, you should connect the Infini to the AC first and then feed the Axpert via Infini. It's still a nonsense, but less dangerous.

Long-story short, daisy chaining the Invertes is a stupid and dangerous idea.
Especially when these inverters are Hybrids (like InfiniSolar is). Especially when 2nd Inverter is more powerfull than the 1st one. Why:
There are no real gains from this setup. Once the Infini will go into bypass because of low-battery, then all the loads will be immediatelly connected to the Axpert. That will cause Axpert's overload and shutdown. Whenever a huge load is powered off then there is an energy spike created. Normally, that spike goes to the grid. But now the spike will be sent into the Axpert's output. Depending on the size of the spike the Axpert will either throw an error, or it's IGBTs will be fried. You CAN daisychain two offgrid inverters, like two Axperts. This type of inverters does not interact with Grid, so all the potential powerspikes are being sent to the batteries. But there's still little to no benefit of doing this.
 
The correct method of combining more inverters into a single system is:
AC coupling for OnGrid inverters like SMA or Fronius. Parallel setup for OffGrid inverters like Axpert. Parallel setup for Hybrid inverters like InfiniSolar or Victron Multiplus.

Right, let me inject a bit of sanity into the "dreaded" (most likely not meant in a bad way) claim.
Way back some BYD batteries came into the country and were sold at ridiculous prices, by a company up North of which the name starts with an H. These guys seems like an upstanding outfit, which is why I prefer not to name names, but in this case I think they made a mistake: They were not sufficiently clear about the status of these batteries. The local BYD guys piped up and denounced the batteries in question and a couple of people, upon discovering what they are really buying, cancelled their orders. This is how the story came across to me anyway.
But then there's also these Revov guys. They are quite upfront about the fact that the batteries are second life, and that is why they are cheaper. They give you a warranty too (although, as always, one would have to see if they are still around in 5 years or 10 years, they may well be). Additionally, I had always known this was going to happen some day. Batteries will be thrown out of more demanding applications when they reach EOL (normally at 80% useable life left), but because these batteries degrade almost linearly over time you could use them another couple of years before they reach 60%, so oversize the pack a bit... and help the world a bit with less electronic waste that will eventually require recycling.
I'm therefore cautiously optimistic that the Revov batteries is a good thing and not a scam. I know quite a few people already who have them installed. The only thing to do is to check BMS compatibility with whatever inverter you intend to pair it with.

Yet they mostly don't. Most people in my neck of the woods (which is not that exclusive) could afford a grid tied solution. But they don't do it. Most people in my street don't even have a UPS or a genny. 

I have people in my family from well off to very rich indeed. None of them have so much as a UPS. They are amazed to hear that I have solar, and hadn't even inquired to find out how much such a thing could cost. They seem to prefer sitting around in the dark complaining about the government.

Thinking of all the people that I know who have got rather more tom than I do, none of them have any kind of domestic electricity backup.

Why this is, I don't know. I suspect that in one particular case there is a complicated set of companies setup so that he actually pays rent to himself or something, but which also makes it hard for him to make changes because that may raise questions (should anybody actually notice) of whose home is it and who is paying for the modifications.

I have a single phase inverter. I can't speak about the 3-phase or industrial products products but I wound't recommend the SolarEdge setup I have for a few reasons. I would much rather have gotten a Victron inverter if I knew then how much  I now know about solar tech. I'm actually planning on getting a Victron Multiplus to add to the SolarEdge inverter.

Milk it @plonkster, milk it
 

Yeah, haha I think I get it. It's like the people who claim you can have more money in your pocket if you earn less and fall into the tax bracket below. If my assumptions are correct, if you buy enough you could be buying multiple tiers of electricity at once.
So, actually, if you buy more than enough electricity to last you until the end of the month you are doing yourself in.
Wow what is up your CoCT prices? Your top bracket is 256c/kWh. Perhaps this is outdated or perhaps there are more brackets than Tshwane shows but their top tier is 195c/kWh. Ah wait, I see where the confusion comes in. I assumed that Tshwane's rated are VAT inclusive but after seeing that CoCT mentions prices with/without VAT I double checked Tshwane's pricing and I see that right at the top of the 26 page document, it mentions that prices exclude VAT. I never actually checked how many units I got because with the non-Conlog smart metering project you loaded up money, not units.
That makes quite a difference to my battery feasibility calculations. Back to the drawing board.

Bad news guys: I'm sorry to report this Conlog has said that Tshwane would rather you disconnect your system than try figure out a solution (an easy token).
 
Thanks for nothing DA. Why do they have this stance whereas in CoCT they are embracing it and even offering feedback at reasonable rates. I wonder if they really are experiencing technical challenges or if that is another cover-up story.
 
I'm not sure what my installer did but they got my inverter (SolarEdge) to stop tripping the meter. I'm not sure exactly which settings they changed but I've notice that no matter the PV output, at least 200W will always come from the grid. Has been working perfectly for a few days now. Perhaps try doing this with your inverter?
Letter.pdf

I phoned for an update yesterday (Monday). It sounds like it's a small office because the support agent said he did not see the engineer come in today. He said that he is not away on training or leave so he should be back soon. Perhaps sick?
 
If this was a gov company like Tshwane or Telkom my BS meter would be going off the charts but I'm going to give them a chance before I make a judgement. It's only been one full working day since the ticket was opened.

I can't see why you would need to charge it up quickly besides for EV usage.
Tesla's current supercharger supports 150kW DC with plans for the next generation to support 350kW. It just amazes me how they can put these just about anywhere they like. How is there infrastructure to put down a 10 bay supercharging (Decent size. Biggest stations are 40 bay whilst the average is 8.3) which, from what I've gathered, has capacity to charge all bays simultaneously at 50%.

I can't see why you would need to charge it up quickly besides for EV usage.
Tesla's current supercharger supports 150kW DC with plans for the next generation to support 350kW. It just amazes me how they can put these just about anywhere they like. How is there infrastructure to put down a 10 bay supercharging (Decent size. Biggest stations are 40 bay whilst the average is 8.3) which, from what I've gathered, has capacity to charge all bays simultaneously at 50%.

Rock solid yes, thing almost broke my back 😂

Can confirm. Just had my smart meter replaced with a Conlog BEC44 and now it is tripping with my solar system. It is a lot more sensitive than the previous meter which never tripped at all even with the 25kWh/year diverted into the grid. Perhaps the Siemens smart meters didn't even have feedback protection. Phoned Conolog on Friday 4:30PM and the support guy took my meter number and said he would personally contact me with the token to disable the feedback protection as soon as he gets it from the engineering team. I'm very impressed with their service thus far. He apologized and said that they take their customer satisfaction very seriously and it sounded like he actually meant it. I was expecting him to tell me to phone Tshwane and sort it out with them since I'm not even really their customer.

Can confirm. Just had my smart meter replaced with a Conlog BEC44 and now it is tripping with my solar system. It is a lot more sensitive than the previous meter which never tripped at all even with the 25kWh/year diverted into the grid. Perhaps the Siemens smart meters didn't even have feedback protection. Phoned Conolog on Friday 4:30PM and the support guy took my meter number and said he would personally contact me with the token to disable the feedback protection as soon as he gets it from the engineering team. I'm very impressed with their service thus far. He apologized and said that they take their customer satisfaction very seriously and it sounded like he actually meant it. I was expecting him to tell me to phone Tshwane and sort it out with them since I'm not even really their customer.

That was actually the weird bit. The car would sense when it was being tested, and swap in good values. With these values it used more fuel, but it made less Nox. These are also the values that went on the sticker and into the advertising. But then when you actually took the car on the road, it would swap in the more economic values (that also made more Nox), so the buyer would get better mileage than advertised. And that has never made sense to me... the guy has already bought the car... you have no edge in advertising. Were they hoping word of mouth was going to do it?
So the analogy for batteries would be that they will understate the vehicle travel distance, and then once on the road some illegal setting will flip and it will go like 30% further... 🙂