3 hours ago, Robbo said:

So in my calc I considered a few things:

Yes your batteries can go down to 20% SOC but what are you actually comfortable taking them down to daily? My Pylontechs can go to 5% SOC per the warranty but i also want a little left for safety and surprise loadshedding. So in my ROI calc I used a 20% SOC in my daily cycle and not 5%. This is up to you but realistically you dont want the battery to shut down daily.

Secondly as someone else alluded to, how often will you use the stored capacity? My personal experience is that i cycle my batteries 24 times in a 30 day period (80% of the time). Now this may seem like I'm using the full daily discharge from point 1, but the reality is that there are cloudy patches and so there is some dynamic use of the batteries during the day as well, not just overnight usage.

Finally for my own calc, my usage would get a useful life of nearly 21 years! (6000cycles/24 cycles per month/12months). I hope this will be true but it isnt realistic in my eyes. So I took the shorter of the cycles and the warranty and used 10 years. so 10 years x 24 cycles per month x 12months = 2880 cycles.

Cycling LiFePO₄ down to 10% is not a problem.  I wouldn't go lower than that, but even at that kind of depth, your daily cycles should still be able to hold you over until you hit the 8-10 year mark.  You are unlikely to even get 10 years, 8 years from research I've read is a realistic amount of time assuming you aren't keeping the cells too hot.

Deep cycles is a problem for lead acid because they sulfate while not being charged (literally things build up over the plates making it so they can't take charge).  Lithium batteries age slower at low rates of charge.  Lithium batteries age fastest at full charge.  They have a totally different set of concerns than lead acid, so best not to apply the logic of lead acid to Lithium (ie. acceptable depth of drain is totally different between the two).

@Robbo yep that is super conservative in my eyes. The guys doing the scientific experiments indicate that these batteries can take a beating and you will be able to get through those 6000 cycles. Their studies are done in months though, so I'm not sure how bad the calendar aging factor is... maybe nobody knows because they haven't been around long enough.

But if I take your 2880 cycles, that means 11059kwH produced, which means R2.07 per kwH (22,995 / 11059). Still not bad, since I'm paying more than that currently (+- R2.60), and it's likely to go up 15-20% per year over the next few years. The cash outlay is large, but let's say you are in the fortunate position to have an access bond and some spare cash in it, I would guess at 7.25% prime, it's worth it. You get a warm fuzzy mostly off-grid feeling, you're covered for most load shedding scenarios, and you're utilising your excess solar better.

As suggested by @Tariq I've got to wait for a winter to really get a sense for whether I need an extra battery.

On 2021/12/09 at 9:07 AM, RichardZA said:

Hi all

With Eskom going for another 20% increase, I think it's time to revisit battery economics vs using the grid.

My problem is I can't seem to find all the info required. I use these batteries

https://solaradvice.co.za/product/fusion-4-8kwh-block-lithium-ion-battery/

Let's ignore installation costs for ease of calculation. Let's also assume that you have solar panels that you haven't maximised (e.g. you have excess solar that you cannot or do not want to send back into the grid, and that these batteries will be filled with excess "free" solar that would otherwise not be utilised).

R22,995 for 4.8kW / 80% DOD / 6000 cycles.

When the manufacturer says it can do 6000 cycles at 80% DOD, what do they mean? Do they mean 6000 cycles x 3.84kW = 23,040kwh throughput during its lifetime? Or do I need to take degradation into account - I assume a "cycle" is 3.84kW as advertised? 

Because if I can buy R23,040kwh prepaid for R22,995 in today's rands (R0.998 a kwh), that is an absolute steal. I could calculated with interest and eskom projected increases, but ignoring that for simplicity (likely eskom increases will outpace prime lending rate). It would indicate that anyone buying solar panels should size a battery rack to store as much excess power as possible (even oversizing the batteries just extends their life so not a waste to oversize a little?)

Please correct me!

Thanks,
Richard

 

 

An increase of 20% is a very good thing. 

Then I get 20% extra on my electricity feeding back into the grid.

So please stop complaining it a very good idea.
Next year they must ask for another 20% then I get even more.

I do not have to worry about cells not charging properly get additional equipment for monitoring the cells.  This means I immediately get more back and a far better and faster ROI.

Yes they must get the 20%.  I

What a pleasure I am getting 20% increase because other steels.

They should actually award Eskom 30% increase.

Go for it I am smiling all the way what a pleasure.

Dankie Oom Zuma & Co

 

 

Edited December 10, 20214 yr by Erastus

15 minutes ago, RichardZA said:

As suggested by @Tariq I've got to wait for a winter to really get a sense for whether I need an extra battery.

I have a 6.43 kWp array and there were a lot of Cape Town winter cloudy/rainy days could not fully charge my batteries, so no use getting another battery, only thing would be if CoCT made it easier and cheaper to feed in to the grid, then you could store surplus credits in summer and use it in winter.

its not 20%, news this morning is 44% over the next 3 years, 20%, then 14%, then 10%, expect the 14 and 10 to actually be more.

also each increase has a compound effect on actual price increase

I read it over my morning coffee, so all from memory now, might be slightly off

 

Edited December 10, 20214 yr by Nitrious

Good grieve,

 

Reading all the issues with batteries I am so glad I dumped mine went on grid smiling all the way and final;y I am getting my monies worth.

A lot was attacking me when I indicated that batteries are extremely costly and almost useless COMPARED TO GRID TIED and thanks to all I never knew so many agrees with me.

 

Think about it no extra logic, electronics.  My light backups are from a few 12V gel 7.2A @ R70 when they go I dumped them. I do not worry about heat, Celsius cost cycles over voltage under voltage R140 and I have 7 hours backup.  After a few years I dumped them and thanks to Eskom increases I do not feel the pain.

To all of those underlying my point about batteries not worth it and very expensive and requires a lot of additional junk to try and make it successful I appreciate your support,

Thank you.


Many thanks  to all this article underlines why people should go grid tie and not support the Chinese and buy a lot of expensive problems!!!

21 minutes ago, Tariq said:

I have a 6.43 kWp array and there were a lot of Cape Town winter cloudy/rainy days could not fully charge my batteries, so no use getting another battery, only thing would be if CoCT made it easier and cheaper to feed in to the grid, then you could store surplus credits in summer and use it in winter.

So 'n  bek kort jam!!!!!!

@Erastus, why don't you post your rates sheet that shows you getting all this money back from the city

I have already done it in another topic
So why do it again?
If people did not believe that then why should they believe it now?

Any person should be able to calculate.  If I paid R3500 per month electricity and now pay R0.00 I save R3500 or 12 x R3500 = R42000 per year.  If I have to replace my batteries I must safe this and donate it to China again. Very basic stuff.

My system cost me R56K my backups  a few bob if they die I through it away and get a new battery 12V 7A  R75 x 2.

Thus R56000 - R42000 = R14 000 left in 12 months.  It is actually more but lets keep it at this it is easy maths.

In fact my system is so basic, ugly and so stupid I am embarrassed to refer to it. Some of my panels I bought second hand because others thought it was rubbish.

Few years back I had 4 rows of 4 x 12V x 200A that I charged with out an MPPT.  I sold it as scrap and got a few R000  for it.  Then the decision was made no batteries again.  Please note if you have to use batteries then this is not part of it.

I am too embarrassed to compare my system  to those who spend R100-R200-R300K.

But then If your electricity is R2000 a month and you save R1800 on a R200K system which is not much BASED ON THE INFO  of others writing here it will take 100 months to break even.  Then I would like to know who has a R200 000 system with fancy batteries pays no electricity have no issues and in 12 months got 75% back on what they spend had no problems and did not have to lift a finger.  Can you guys send me the list please. Let me make it clear to do my job for me I got 75% back in 12 months.  If you spend R100 000 then you must have save R75000 in a year R200 000 savings is R 150 000.

Please do not forget the list I would love to go and visit and see them. There might be so many that me and my wife can go on a year touring journey to visit the people.

By then the reality is after some time your batteries from what people write will have issues and then it will cost a this and a that and another amount of money. This is not me writing this, this is clever people on this blog with expensive batteries and ..... Therefore shoot them not me.  Take note I have spend 000 except if I expand to caver more the get more back.  Not a singe cent.

Imagine I spend R0.00 with a pathetic system.  The only problem I have no brag rights as it is basic, cheap, ugly and pathetic and even second hand I never have to ask about battery voltage charging systems maintenance.  My system has no issues and now I am doing the wind turbine.

From my little database and info gathering I am now challenging the calculation of electricity for grid tied systems. I have asked for time billing and ..
Next year  I will make a proper submission to the mayor comity to re look at "kick back" and...

I wonder how many will have to support China for odds and sodds?

The facts if we do not calculate argue and get inputs we all can fall in a grove and the difference between a grove and grave is the depth.

The calculation on feeding back and profits is extremely simple and so are those on expensive batteries.
The people who write in this blog constantly have issues please TAKE  NOTE NOT ME THE PEOPLE PRO BATTERIES.

The cost of batteries are a given, the maintenance and up keeping as put out in this article nothing but a disaster and always another expense.

I am not going to do the calculations but let me share with you a little what I do. My business equipment must have a 24/7 up time else I am loosing a lot. I tried all batteries for load shedding for our electronic equipment. My 12V 10X and 200amp batteries are 4 - 7 years old. These batteries I paid R1800 for a 120 amp battery.  The chargers I have designed and use is extremely low cost try it 50a 12V/24V R195. So if you truly want to take me on get any one on this site to compare batteries with batteries. If you want to go one step further I can show you comments from the design engineers of major suppliers of batteries commenting on my designs.  In no other words cost wise, easy replacement wise and maintenance wise there are some batteries that I can not recall when last we have visited them.  Every single outage for the past years they operated and still going strong. I do not know what the cell voltages are or have to worry about this or that.

Would I swap them for these expensive stuff not in a million years.

Sorry to say batteries are not there to safe with. They are there to supply power in an emergency and never a good product to safe with.

This may create a far more sinister messages but roughly put read what the people NOT ME say about the expensive stuff.  Some one tried to sell a faulty battery for R10K. It fascinates me that people still try to convince people to get batteries after I would argue the most articles is on this blog contains "expensive batteries life cycle and charging and maintaining" it. Why on earth would I dig a deep whole for myself and almost kill myself by jumping in it?

Not me chatting about it but others.  Go and read it.
 

The interesting point is every one discusses how to get maximum charge, maximum life how expensive these wonder batteries and they are better than sliced bread.  Well I do not talk about my system it simply works requires no attention and no costs.  As a fact it is the reason why less money is leaving my pocket.

But why then does so many struggle with these wonderful products?  Help me understand it please.  If the suppliers know what they doing and they can't better on my dumb and stupid deep cycle batteries how on earth must I believe that it is a good product when almost every article is about struggles?

If they are that wonderful as many claim I am sure Ferrari will pay you millions to get them for F1 racing.

What I don't understand not a single person in a single discussion could explain TOTAL cost and savings versus grid tied. 

Let me return the challenge you beat me and proof me wrong then next year I will arrange for an Ox braai for those who wants to come and enjoy the day with who are there. Free and on me.  Any one can challenge me if I am right then you pay for it and pay me double. In short put your money where your mouth is I am prepared to do that.

Please not you are more than welcome to insult and challenge me.

Something went wrong with cut and paste  I will fix it and paste again

Coun Col	R @ Step T
R 386.77	R 397.90
R 430.67	R 430.67
R 505.36	R 505.36
R 576.29	R 576.29
R 591.49	R 591.49
R 621.34	R 621.34
R 559.28	R 559.28
R 463.78	R 479.68
R 342.63	R 371.24
R 377.23	R 396.89
R 435.21	R 448.50
R 525.02	R 562.13
R 314.40	R 443.25
R 198.71	R 396.29
R-174.11	R 268.36
R-380.42	R 237.76
R-595.19	R 214.21
R-911.39	R 179.05
R-1,036.43	R 188.49
R-310.38	R 345.16
R-228.04	R 341.87
R 31.63	R 412.71
R 641.31	R 973.62
R 536.83	R 946.33
R 236.33	R 812.78
R-532.08	R 307.50
R-493.81	R 366.00
R-493.93	R 352.97
R-187.50	R 112.45
R 2,431.00	R 12,839.59

Edited December 10, 20214 yr by Erastus

1 hour ago, RichardZA said:

Still not bad, since I'm paying more than that currently (+- R2.60), and it's likely to go up 15-20% per year over the next few years.

100%, if you are conservative and it still makes financial sense then you can celebrate when you outperform your expectations!

54 minutes ago, Tariq said:

@Erastus, why don't you post your rates sheet that shows you getting all this money back from the city

Exactly

1 hour ago, Nitrious said:

its not 20%, news this morning is 44% over the next 3 years, 20%, then 14%, then 10%, expect the 14 and 10 to actually be more.

also each increase has a compound effect on actual price increase

I read it over my morning coffee, so all from memory now, might be slightly off

 

That is actually 50% over 3 years, using this year's tariff as a base. 

IE If you are paying R1 per unit now (I did say "if") you will be paying R1.50 this time 2024.
 

The article had it at 54%, I corrected to compound removed to avoid confusion, tried to find the original article, but couldn't

And here we go again:

Info/Opinion on system not delivering as expected
Look at the article ...

20 hours ago, Tariq said:

@Erastus, why don't you post your rates sheet that shows you getting all this money back from the city

Tshwane pays 11.4c I pay them on average R2.80. So I would have to sell about 25 units to cover me for one night-time unit. If I use half my 30kWh at night, I need to sell 30/2x 25 = 375 units per day to break even. With a yield factor of 6 that is 62.5kWp or 150-180 panels ... simply infeasible. Simple maths tell me no-one has enough roof to break even with backfeed in Tshwane. So it is a non-argument.

Edited December 11, 20214 yr by Scubadude

Depends where you are, the western cape seems reasonable 

https://www.westerncape.gov.za/energy-security-game-changer/small-scale-embedded-generation-sseg-feed-tariff-map

I can fit around 24kw on my roof, assume 3300 units per month, self consumption, say 800, export 2500, could maybe work at 0.80 tariff which some Muni's give, I'll take a better look in the morning, this is worked out on my phone 

Edited December 10, 20214 yr by Nitrious

5 hours ago, Erastus said:

Good grieve,

 

Reading all the issues with batteries I am so glad I dumped mine went on grid smiling all the way and final;y I am getting my monies worth.

A lot was attacking me when I indicated that batteries are extremely costly and almost useless COMPARED TO GRID TIED and thanks to all I never knew so many agrees with me.

 

Think about it no extra logic, electronics.  My light backups are from a few 12V gel 7.2A @ R70 when they go I dumped them. I do not worry about heat, Celsius cost cycles over voltage under voltage R140 and I have 7 hours backup.  After a few years I dumped them and thanks to Eskom increases I do not feel the pain.

To all of those underlying my point about batteries not worth it and very expensive and requires a lot of additional junk to try and make it successful I appreciate your support,

Thank you.


Many thanks  to all this article underlines why people should go grid tie and not support the Chinese and buy a lot of expensive problems!!!

I'm confused, do you have a Hybrid inverter with panels, that push back power into the grid, and therefor you're saying you are a net supplier  to City of Cape Town, or are you fully off grid with 12V 7.2AH batteries for lights, and maybe a generator? An explanation of your system would be great.

I started with 12V DC lights throughout the house, then a bunch of pure sine wave inverters, and now am happy with a SunSync 8.8K machine with panels and lithium batteries. I absolutely have to have good batteries, as the power grid in my area is Bad. There have been times the power is off for days, and some weeks we experience three power outages a week, which has nothing to do with load-shedding. Oh, and as a final backup, I also have a generator. For those who don't believe me, come to KZN, midlands. 😂

@RichardZA Batteries, and more batteries, plus panels to charge them, as the power grid countrywide will sooner or later get even more unreliable.👍

Edited December 10, 20214 yr by TimCam

4 hours ago, 0012 said:

Exactly

It has already been posted. So why again?

2 hours ago, Nitrious said:

Depends where you are, the western cape seems reasonable 

https://www.westerncape.gov.za/energy-security-game-changer/small-scale-embedded-generation-sseg-feed-tariff-map

I can fit around 24kw on my roof, assume 3300 units per month, self consumption, say 800, export 2500, could maybe work at 0.80 tariff which some Muni's give, I'll take a better look in the morning, this is worked out on my phone 

This is a problem.  Therefore should we not draft a "petition" and get this "enforced" as the tariffs are enforced?

Currently I am debating with the local people on the basis if we have time based meters and which is a requirement why do we not get time based billing.  I fixed the cut and paste.  This is what the COCT should have paid Eskom for my electricity  R 12,839.59.  If they are paying Eskom  R 0.391  per Kwhr at night and they take 100% markup we should pay R0.80 not R2.00

Note that from Sept 2019 - Aug 2020 nothing  registered on my account.  Then in Aug 2020 the council did something and the feed back registered. 
Still incorrect but it was something.  After some issues they decided to replace my meter late Oct 2020 and the rest is clearly obvious. 
Then June July Aug I worked on my house and solar was not working 100% as I had to move all my panels remount them as my house developed a serious water problem with the water rushing in through my concrete top and caused sever damages to my house.

15 MONTHS I had bad figures and since Aug 2020 after calculating what they had to pay and the difference by selling my electricity which they "now get for free" my total electricity cost them R 2431. That is from Aug 2019.

Now do the calculations then you will actually see how much they are reaping from us.
On top of this they have a moving billing period.  This playing with dates cost and extra amount R6758 for this period mainly in early 2020.

Coun Col	R @ Step T
R 386.77	R 397.90
R 430.67	R 430.67
R 505.36	R 505.36
R 576.29	R 576.29
R 591.49	R 591.49
R 621.34	R 621.34
R 559.28	R 559.28
R 463.78	R 479.68
R 342.63	R 371.24
R 377.23	R 396.89
R 435.21	R 448.50
R 525.02	R 562.13
R 314.40	R 443.25
R 198.71	R 396.29
R-174.11	R 268.36
R-380.42	R 237.76
R-595.19	R 214.21
R-911.39	R 179.05
R-1,036.43	R 188.49
R-310.38	R 345.16
R-228.04	R 341.87
R 31.63	R 412.71
R 641.31	R 973.62
R 536.83	R 946.33
R 236.33	R 812.78
R-532.08	R 307.50
R-493.81	R 366.00
R-493.93	R 352.97
R-187.50	R 112.45
R 2,431.00	R 12,839.59

Edited December 10, 20214 yr by Erastus

54 minutes ago, TimCam said:

I'm confused, do you have a Hybrid inverter with panels,

Nope I have three grid tie inverters.  My old inverter that I used with the 48V if you wish batteries is standing some where and rusting. 
I use 2 x 12V 7.5A batteries a small charger for my lights backup ..

When I started grid tied I was not sure so I bought a 1.2Kw Solis.  It did not last in my conditions and the salt / damp blew the in puts.

Then there where some shortages and I got me a 3k3 solis grid tied.  Cost was if I remember correctly R8300 hope I am right.

Then my other 2 cost a little more at R5K each.  Three inverters something like R18300 can't remember the Solis price.
I don;t bother about the stuff anymore but I think I have 8 or 10 second hand 330W panels.  It was around 12K for it could not remember. That brings me to R30K keep the change.

Like I said others thought its rubbish its still generating the same power as when I got it.

When my wind genie works properly I recon I will add another 2 10Kw units.....  Because I am designing the electronics the genies will connect to the 10K plus these units and I recon in the good winds I will push 14 - 17Kwhr per turbine. Or in low winds something like 350W.

Trust me it is basic installation.  I took a dedicated 3 phase cable from my 1 DB to the roof. Have an isolater switch 3 phase.  This T in after my main cct breaker.  In the meter box on the pavement I have 3 120A breakers.  Each inverter has its own cct breaker on mains.

No junction boxes no other electronics except my own  power meter.

Three DC fuses for the solar panels.  Mean and lean.  Each inverter has its own set of panels with a good 220V cable to the little DB  with breakers.

It complies to all specs rules and safety and ... In total 9 meters conduit. The cable was expensive as it is a 4 wire 120 amp per phase cable if you wish.

And that is it. Not impressive not expensive not fancy not something I will show photos of as it is nowhere in the league of what is installed and showed on this blog and rightfully laughable.  Some people that came to look was shocked how little and how basic. A proper cheap and nasty was a comment.

The back up. They are either 12V or 24V depending of the LED lights.  I started running 12V then realize its a waste. 

I am getting another 5 batteries next week for some more stuff  and they are brand new R75 each.  Gell no fumes no issues no ...

It can either switch automatically to backup lights or switch on via a switch or CPU

Cheap and nasty and extremely effective. 

The COCT currently pays:

R 0.7551 per Kwhr and an incentive of  R 0.25  a total of R 1.01 EX VAT.

My average usage per day is 9Kwhr when my solar runs 100% normal and in the installed positions
This cost me  +/- R 18.09 per day or 20Kwhr push back then I have a 0 account. I do not want to give my exact Kwhr on this page but I can assure you I do not measure in Kwhr for my electricity generated...

They also increase it with the Eskom rates then a 20% will be R 0.91 + R0.25 = R 1.16.

If only they can go to time based billing.

Now in Cape Town the calculation are benefiting the council but not worth while to support China.

Edited December 10, 20214 yr by Erastus

@Erastus options for people e.g. in jhb? 

 

6 hours ago, RichardZA said:

@Erastus options for people e.g. in jhb? 

 

Let me check on this. I never bothered to check else where and ask about it maybe its time to do so.
Wonder how many others will be interested should Jhb offer the sam as Cpt....

 

I would start by seeing if your muni has a sseg tariff program. here's a link, info can be outdated, keep that in mind - https://www.sseg.org.za/

the one's in trouble like mine, have simply abandoned the process by the looks of things, so I'm stuck on self provisioning, read batteries, borehole etc etc, as well as weird meter readings, hence getting "off grid".

if your muni doesnt support sseg tariff's, it may be worth picking it up a group like outa, maybe not them per say, but you get the idea.

there are costs to getting your setup certified should it be an option, make sure to see if its worth it for you.

there are tax breaks for solar, last I checked its 50% in the first year, so on and so on, maybe that helps

keep in mind I'm been professionally out of solar since covid hit, so some of my info may be lagging behind.

lastly I'd look at keeping system capital costs very very low, just before covid came along I had arranged to get solar panels in bulk (containers and containers) at a fraction of current pricing, this could be re investigated, as I recall 10kw panels were around 15K or so.

 

18 hours ago, Erastus said:

A lot was attacking me when I indicated that batteries are extremely costly and almost useless COMPARED TO GRID TIED and thanks to all I never knew so many agrees with me.

 

I also 100% agree with you that the grid is your best battery. My father in the Seychelles has solar and the municipality allows 1:1 credit for your solar output - e.g. if you put 1kwH into the grid, you get 1kwH in credit on your account (you an only spend the credit on electricity, they will not pay you out). He has a beautiful bell curve of power production every day and a couple of small batteries in case the grid goes out (rare but it does happen).

My challenge is City of JHB and most of the country outside of the Western Cape will either pay you nothing for your feed-in or close to nothing 10c-30c per kwh, plus jumping through several hoops. So the question is where do we focus our efforts - do we think there is a realistic chance of persuading City of Johannesburg or others to give us reasonable tariffs. Might be easier to move to the Cape!