mmacleod

I find this a tricky one.

What I like about pylontech is that they are clearly a solid product, they're generally known to be good with quite widespread usage, with independent tests in which they do very well and outperform a lot (most) of the other lithium batteries tested. I'm very happy with the one I have now and strongly considering to just expand with them, they're a solid product.
I feel like I can buy a system that will use them right now, punch the numbers into my ROI formula to see what ROI will be like over 10 years and expect them to actually last 10 years, and that if they don't there's a reasonable chance (assuming I install them decently) that they will be replace under warranty and/or that the company will still even exist to do so.

A 20% discount on the other hand is nothing to sniff at and if I could get the same thing for 20% less its definitely at the very least tempting.

Dyness on the other feel like a harder to quantify risk.
Yes there are the rumours that the people running it were previously at Pylontech, but even if that were true what exactly does that mean? Are they the people who made pylontech a success or did they leave because they were problematic or pushing Pylontech to be lower quality for cheaper parts and higher profit? How would I know? How much is this connection really worth in reality?
The BMS is apparently the same, maybe that's true.
What about the cells though? Are the cells the same quality or are they maybe sourcing lower quality cells?
Do they even have the same quantity of cells? I see the Dyness 2.4 apparently weighs 22kg while the pylon 2.4 apparently weighs 24kg - could the difference in weight be that the pylon 2.4 actually has more cells and reserves some extra capacity to help them last longer (never reaches as low a state of charge) which in effect means the Dyness won't last as long?
Which then brings me to question, if Dyness batteries start dying 6 or 7 years in will they be around to honour the warranty, or are they going to vanish.
Do Pylontech maybe cost more because they reserve some money for warranty replacements, while Dyness are just yet another battery company (in a long line of battery companies) that are going to vanish from the face of the earth before anyone needs to claim?

So in short, is Dyness cheaper because they have a more efficient manufacturing process and thinner margins, or are they cheaper because they are selling you less and/or have a less sustainable?
I wish I knew that answer to that, I have no idea only questions.
And so it becomes a matter of, take the "safer" but more expensive batteries and have a longer ROI, but be more likely to actually ROI for sure.
Or take the cheaper batteries and have the possibility of a faster ROI, but run the risk of having no ROI at all if the batteries go poof a few years in...

Still thinking about it myself, but I tend to be conservative on these things, for now I favour pylontech, I really like that theres detailed independent testing data as that is something I can really trust to some degree, though I hope someone comes up with more detailed and certain information on the dyness.

Actually aluminium is an excellent conductor and at the thicknesses of the average rails for holding panels will do a much better job than some measly thin copper wire..
From what I understand it is more just because 'thats what the panel manufacturers say in the instructions' and because it is difficult to ensure that all the aluminium peices bond to one another electrically.
The seperate peices are usually anodised which needs to be peirced to conduct electricity and then further aluminum oxide also forms a non conductive skin.
There are special components for this - http://www.we-llc.com/products/weeb-washer - if this link doesn't work google 'weeb washer' to find many hits on it - to me this is a far *better* way of doing it, it makes way more sense.
Anyway this brings me to my question, does anyone know somewhere local that has this sort of product available or could make such a thing?

The reason for the two element geysers, in the UK at least is that you have the option to get "Economy 7" supply when the electricity is cheaper from midnight to 06:00 or 07:00 in the morning, during the day the top geyser element will switch on according to the thermostat setting, heating only a little amount of water, due to stratification, during the cheaper tariff the bottom element will be switched on, and heat a larger volume of water,  and that is also why they are vertical. This option is mostly when you have an electricity only energy supply.
https://en.wikipedia.org/wiki/Economy_7
The geyser @Vasan has shown is used when you also have a gas supply and uses a gas boiler for water / room heating, the electrical element is mostly for backup as the price for gas in the UK per kWh equivalent is far less that electricity per kWh and probably now also less than we pay per kWh for electricity in SA, last time I checked it was around 5 pence per kWh equivalent i.e. ~ R1.10. also depending on supplier as you can actually choose from a number of suppliers.
https://powerforum.co.za/topic/5431-geysers-with-two-elements-in-south-africa/?do=findComment&comment=83693
So much then for Eskom argument of our Electricity being relatively cheap, when you can get cheaper energy using gas in Europe.
 

I was never able to track down an off the shelf part for this, so I'm pretty sure whats in the photo there is a custom made part.
The best option for two elements seems to be to just add an additional pre-feed geyser or similar

In my view I would also like to separate the elements into distinct separate elements one mains and the other solar. The reason being that you do not want to be stuck with a 1000w for solar and say a mains one of 2/3 kW. Also you could use a 110v 2kW element with a DC solar supply directly off the panels and the normal mains element for overcast days or nigth time usage with independant thermostats and supply wiring! Alternately the smaller/larger dual geyser system is probably best for winter when the water supply temperature is first fed into a preheating geyser before being fed into the larger geyser that is feeding the taps/showers. Lots of energy is wasted when the ice cold supply water is fed directly into the larger geyser during usage. It seems that these dual separate element geyser options are not readily available in South Africa unfortunately!

For all my fellow Victron fans out there:
 
 

I see a new test report is out:
https://batterytestcentre.com.au/wp-content/uploads/2020/05/Battery-Testing-Report-8-April-2020.pdf
At about 1600 cycles (4.5 years) having around 85% usable capacity left and seems to still be going strong while some of the other friends have died along the way. 

I find this a tricky one.

What I like about pylontech is that they are clearly a solid product, they're generally known to be good with quite widespread usage, with independent tests in which they do very well and outperform a lot (most) of the other lithium batteries tested. I'm very happy with the one I have now and strongly considering to just expand with them, they're a solid product.
I feel like I can buy a system that will use them right now, punch the numbers into my ROI formula to see what ROI will be like over 10 years and expect them to actually last 10 years, and that if they don't there's a reasonable chance (assuming I install them decently) that they will be replace under warranty and/or that the company will still even exist to do so.

A 20% discount on the other hand is nothing to sniff at and if I could get the same thing for 20% less its definitely at the very least tempting.

Dyness on the other feel like a harder to quantify risk.
Yes there are the rumours that the people running it were previously at Pylontech, but even if that were true what exactly does that mean? Are they the people who made pylontech a success or did they leave because they were problematic or pushing Pylontech to be lower quality for cheaper parts and higher profit? How would I know? How much is this connection really worth in reality?
The BMS is apparently the same, maybe that's true.
What about the cells though? Are the cells the same quality or are they maybe sourcing lower quality cells?
Do they even have the same quantity of cells? I see the Dyness 2.4 apparently weighs 22kg while the pylon 2.4 apparently weighs 24kg - could the difference in weight be that the pylon 2.4 actually has more cells and reserves some extra capacity to help them last longer (never reaches as low a state of charge) which in effect means the Dyness won't last as long?
Which then brings me to question, if Dyness batteries start dying 6 or 7 years in will they be around to honour the warranty, or are they going to vanish.
Do Pylontech maybe cost more because they reserve some money for warranty replacements, while Dyness are just yet another battery company (in a long line of battery companies) that are going to vanish from the face of the earth before anyone needs to claim?

So in short, is Dyness cheaper because they have a more efficient manufacturing process and thinner margins, or are they cheaper because they are selling you less and/or have a less sustainable?
I wish I knew that answer to that, I have no idea only questions.
And so it becomes a matter of, take the "safer" but more expensive batteries and have a longer ROI, but be more likely to actually ROI for sure.
Or take the cheaper batteries and have the possibility of a faster ROI, but run the risk of having no ROI at all if the batteries go poof a few years in...

Still thinking about it myself, but I tend to be conservative on these things, for now I favour pylontech, I really like that theres detailed independent testing data as that is something I can really trust to some degree, though I hope someone comes up with more detailed and certain information on the dyness.

I find this a tricky one.

What I like about pylontech is that they are clearly a solid product, they're generally known to be good with quite widespread usage, with independent tests in which they do very well and outperform a lot (most) of the other lithium batteries tested. I'm very happy with the one I have now and strongly considering to just expand with them, they're a solid product.
I feel like I can buy a system that will use them right now, punch the numbers into my ROI formula to see what ROI will be like over 10 years and expect them to actually last 10 years, and that if they don't there's a reasonable chance (assuming I install them decently) that they will be replace under warranty and/or that the company will still even exist to do so.

A 20% discount on the other hand is nothing to sniff at and if I could get the same thing for 20% less its definitely at the very least tempting.

Dyness on the other feel like a harder to quantify risk.
Yes there are the rumours that the people running it were previously at Pylontech, but even if that were true what exactly does that mean? Are they the people who made pylontech a success or did they leave because they were problematic or pushing Pylontech to be lower quality for cheaper parts and higher profit? How would I know? How much is this connection really worth in reality?
The BMS is apparently the same, maybe that's true.
What about the cells though? Are the cells the same quality or are they maybe sourcing lower quality cells?
Do they even have the same quantity of cells? I see the Dyness 2.4 apparently weighs 22kg while the pylon 2.4 apparently weighs 24kg - could the difference in weight be that the pylon 2.4 actually has more cells and reserves some extra capacity to help them last longer (never reaches as low a state of charge) which in effect means the Dyness won't last as long?
Which then brings me to question, if Dyness batteries start dying 6 or 7 years in will they be around to honour the warranty, or are they going to vanish.
Do Pylontech maybe cost more because they reserve some money for warranty replacements, while Dyness are just yet another battery company (in a long line of battery companies) that are going to vanish from the face of the earth before anyone needs to claim?

So in short, is Dyness cheaper because they have a more efficient manufacturing process and thinner margins, or are they cheaper because they are selling you less and/or have a less sustainable?
I wish I knew that answer to that, I have no idea only questions.
And so it becomes a matter of, take the "safer" but more expensive batteries and have a longer ROI, but be more likely to actually ROI for sure.
Or take the cheaper batteries and have the possibility of a faster ROI, but run the risk of having no ROI at all if the batteries go poof a few years in...

Still thinking about it myself, but I tend to be conservative on these things, for now I favour pylontech, I really like that theres detailed independent testing data as that is something I can really trust to some degree, though I hope someone comes up with more detailed and certain information on the dyness.

There are solutions to ensure anodizing doesn't cause a problem and that all panels/mounting have a conductive connection, however they don't seem to be very popular or readily available in the country for whatever reason. Or maybe its just a case of people not being aware that it is an issue or that there is a solution?
http://www.we-llc.com/products/weeb-washer

Managed to locate at least one local place that has these now:
https://www.lumaxenergy.co.za/product/lm-cgw-2/
https://www.lumaxenergy.co.za/product/lm-sgw/

Somewhat related to this discussion, and also a long time coming:
https://www.pcworld.com/article/3518831/how-intels-changing-the-future-of-power-supplies-with-its-atx12vo-spec.amp.html

 

Yeah, I've seen both of these, neither of them is really as good as an actual unit thats just designed for two elements though.
Also from both a safety and efficiency perspective I'd (personally) like some decent space between the two elements (wiring further apart and so on)

I guess the other option and probably closest I can get to a proper two element geyser,  is to go for two geysers that just connect to one another.

Yes. Two geysers in series with the first one on solar and the second just doing top up temperature is what I am also looking to do.
Two 150 liter geysers is below R6k excluding electrical supply and installation.

You get similar stuff in the local market.  But your eyes are going to water when I give you a price.
Last one I did was a fair bit larger but without any elements (for heat pump) and it came in at R27,000. Smaller unit I would guess about R10k-R15k

Well sure in a completely fictitious example where spending double the money gets you exactly double the savings the ROI is exactly the same.
Well not exactly, because it assumes the costs to acquire the capital are the same - which isn't guaranteed, but anyway...

In reality however the things being talked about are not linear.
A system that attempts to meet 100%+ of demand costs more than a system that is designed just to handle the low hanging fruit.

100% - its much cheaper and much faster in terms of ROI to take only a portion of the household  that you need off grid, than to go full blown solar.
However there tends to be some kind of allure that sucks people immediately into taking an all or nothing approach. This is why solar then has a reputation as being incredibly expensive.

This thread made a 5 year jump but amazing how the questions are still the same.
I'm convinced that here in SA the driving force is the intermittent availability of the grid. So the solution is to address what you need to keep running during power outages. But we get ambitious and start dreaming about going off grid..
There's a massive difference between the two so it's a good idea to think long and hard as to what you actually want (with the power on and if you can when the lights go off as well!)

A copy of the 'system diagram', in case it somehow ends up being useful for anyone - not exactly my finest work but I was angry I even had to spend time on this at all so wasn't really going to spend too much time making it pretty.
 

6x320W (1920W) artsolar panels
eSmart MPPT charge controller
1x pylontech US3000 lithium battery
1x 8 port PoE injector
1x victron orion 48/12 DC/DC convertor  
1x victron orion 48/24 DC/DC convertor
(And obviously assorted cabling/connectors/DC circuit breakers)

Most my network equipment runs off the 48v PoE
My desktop computer itself runs directly from the battery at 48v as well (I bought a 48V DC ATX PSU for it)
My two computer monitors run off the 24v convertor
I'm not actually even using the 12v convertor any more (at a point I had some network devices on it still) but I keep it around just in case

This allows me to endure entire day power outages (happens several times a year) uninterrupted, as well as shorter load shedding periods when load shedding flares up. Which is important to me as  a work from home programmer.
So essentially all my computing related equipment is off grid but the rest of my house functions as normal, I don't really care if my oven etc. goes out (though in my next house I'll probably install more panels and move more things off grid)
 
1) Filled in the four page SSEG off grid application form where I could as various of the parts don't apply or make sense.
2) Crossed out all the parts about inverters or that were irrelevant.
3) Put 'n/a' by the CoC part of 'documents to be submitted'
4) Wrote notes on it at various points that the system was DC only and physically seperated from the grid.
5) Hand drew a 'system diagram' of the whole thing
6) Sent them an email of the above, and mentioned in the email that their requirements in terms of system diagram are vague and the I won't pay for an electrician to do all of this unless they first clarify various of the requirements to avoid a double call out.

I then waited about 9 months and in February out of nowhere it was completed, I was never contacted and nobody came to inspect, or if they did I'm not aware of it happening (so its unlikely)

Reminds me of the following XKCD webcomic 🙂

Yup. Might be easier to put a temperature sensor in there and be done 🙂
 

You are right I think, I have it backwards. My main point was that they differ in spectrum, and in my eagerness to try demonstrate this in a simple analogy I ended up a bit far from the truth.
This stuff (light spectrums) is way out of my comfort zone in terms of knowledge, I only know that there is definitely a spectrum difference and that this alone probably makes any extrapolation between the outputs of the two 'tricky' at best.

It would be nice to have a better mental model of which parts of the spectrum the different types of PV panels/heating systems on the market actually rely on - and what the given energy in each of those spectrums tends to be for various types of common weather conditions. Something that is easily digestible by us laymen, I tried a brief search on the subject now but theres no super great resources on it to be found.

Another point to keep in mind is that PV Panels generate optimal power in sunny and cold conditions, whereas solar water panels work best when it is sunny and hot.

thanks mmacleod - I was just wondering If I could make an estimate within a certain day temperature range. But You guys are right I think that there are so many other factors to consider as to the make the "estimate" unreliable" - still would be a good study/experiment.