pilotfish

This has been done before by people much smarter than me;
  Fixed Adj. 2 seasons Adj. 4 seasons 2-axis tracker % of optimum 71.1% 75.2% 75.7% 100% The table above shows that there is hardly any value at all in adjusting panel tilt each season over a fixed tilt array, however there is a very real advantage to a 2axis tracker over fixed array.
The above numbers don't really tell the whole story - for a fixed array to theoretically match the annual output of a 2axis array you would need to add 40% panel capacity, but the larger fixed array would still give low output in the morning and evening with a huge output in middle day, whereas the 2axis array would give a much smoother output throughout the day.
This smoother output would deliver significant benefits in real life over the simplistic result of math on a piece of paper showing equal annual output. To have your output pick up quickly in the morning and extend PV output late into the afternoon would have significant benefits in an off grid situation (and most other situations as well).
 
 

All grid-tied installations, irrespective of the size, have to follow the process outlined by City Power for the Johannesburg metropolitan.
PV system installation in Johannesburg
All City of Johannesburg customers planning for PV system installation should follow the permit application process prior to installation and commissioning of the PV system. It is mandatory for customers with PV systems already installed to follow the same process and register/regularize their installations with the system and connection requirements of City Power.
We advise that all our installers familiarize themselves with the permit application process and hope that the following few point can assist in ensuring responsible supply of world class tier 1 PV equipment.
Applicable standards and guidelines
The technical requirements for Small Scale Embedded Generation are covered in the following standards and guidelines. All installers preparing for an application should ensure compliance with the SSEG standards and guideline indicated below, among other recognized standards:
1. City of Johannesburg By Laws for Electrical Connections
2. SANS 10142
3. SANS 959
4. South African Renewable Power Plant Grid Code.
5. NRS 097-2-1 Grid interconnection Generation (Utility interface)
6. NRS 097-2-3 Grid connection of Embedded Generation (Simplified utility connection     criteria for low-voltage connected generators).
7. IEC 62116 Test procedure of islanding prevention measures for utility-interconnected     photovoltaic inverters.
8. IEC 62109-2 Safety of power converters for use in PV power systems –
Part 1: General requirements.
9. IEC 62053-22 Electricity Metering Equipment
10. IEC 60364 – 1 Low Voltage Electricity Installation
A site survey is very important as many installations are done at sites were pre-paid meters are currently installed. No system will be allowed to be connected to a pre-paid meter even if the system will have zero exporting.
The only meter that is currently re-programmable for bi-directional application is Itron. All other meters will need to be replaced. Provided all embedded generated power is legally connected by following the permit application, City Power welcomes grid feeding of all Renewable energy sources.
Acceptance of the plant
Once all commissioning tests have been completed and the installer has issued the relevant COC for the installation, it will be the responsibility of the Installer to notify City Power of the status and request an official commissioning date. City Power will provide a date for their Engineer to visit the site together with the registered PR engineer and the commissioning documents will be signed off simultaneously by both parties at the site.
Embedded Generation Tariff.pdf
COJ Tariff - TOU.pdf

Hi @WillieC
Your system appears to be 3x Axpert MKS 5k inverters in parallel, with 8 panels connected to each inverter probably arranged as 4 strings of 2 panels in series, and an 800Ah common battery bank made up of 16x 200Ah batteries arranged in 4 strings of 4 batteries.
The software that you require to monitor your system is ICC. It comes in Rasberry-Pi and Windows versions, but not Mac as far as I am aware. I run it on an clunky old Pentium Laptop running Windows 10 and it works brilliantly - in fact I don't know how anyone could effectively run a PV system such as the one you have without similar monitoring software. You can download the software for your chosen platform at http://iccsoftware.co.za/about/download-2/
The computer (whichever route you decide to go) is connected to 1 of the 3 Axperts via the USB terminal.
I would also recommend that you get a Victron BMV-702 which addresses the 1 major fault of the Axpert (and most other inverters as well) being the method used to monitor battery State Of Charge (SOC) - the Axpert estimates SOC via battery voltage, whereas the BMV measures amps in/out of the battery which is a vastly more accurate method. Accurate SOC information is important for ICC to make accurate decisions on when to switch between Grid and Battery modes in order to protect your batteries from damage (lets hope you are not too late). The BMV will also communicate with ICC via a USB connection
ICC is like a high performance athlete on crutches without the BMV. If you decide to go this route then contact @Camel regarding the BMV and he will provide you with the correct equipment.
It all sound a bit complicated but really isnt once you get started - some sameples of ICC output below.

Nope, the battery is a commercial unit with bms, inside a steel box with cells firmly secured, with a circuit breaker that is turned off so that the terminals on the front are dead - off course if you dragged it from JHB to Durbs behind your vehicle then there might be some problems.

I am not going to get involved in this discussion other than to offer this one opinion (because the conversation is an endless circle);
There is no value in installing a grid connected system in JHB (which includes any inverter that connects to the grid, irrespective of its ability to feed back into the grid). The authorities have carefully calculated costs and complexities to make it just a dumb thing to do. In my opinion this is intentional to protect their revenue stream of which electricity sales is the major contributor.
If you want to move forward with solar then make sure you are "Off Grid" in that your inverter and the grid never meet. This can be accomplished by Having a Grid DB for things like Oven (gas?), geyser (solar?), A/C, under floor heating etc. Then have a PV-DB for lights, general plugs (not space heaters), fridge, TV+Decoder, PC's, internet, etc. You can have Grid Backup for the PV-DB via a suitable separate changeover switch.
This solution (off grid) will require that you register with Nersa as an SSEG when the time comes and regs are settled (unless panel capacity is below a pathetic 250W apparently), and have a COC for the installation - but no special applications, approvals, engineers, tariff changes etc etc etc
If you look at the numbers and feel that there is value in going the Grid Connected route then go for it.

@BowsieThey do.
Din_Changeover_Onesto.pdf

All grid-tied installations, irrespective of the size, have to follow the process outlined by City Power for the Johannesburg metropolitan.
PV system installation in Johannesburg
All City of Johannesburg customers planning for PV system installation should follow the permit application process prior to installation and commissioning of the PV system. It is mandatory for customers with PV systems already installed to follow the same process and register/regularize their installations with the system and connection requirements of City Power.
We advise that all our installers familiarize themselves with the permit application process and hope that the following few point can assist in ensuring responsible supply of world class tier 1 PV equipment.
Applicable standards and guidelines
The technical requirements for Small Scale Embedded Generation are covered in the following standards and guidelines. All installers preparing for an application should ensure compliance with the SSEG standards and guideline indicated below, among other recognized standards:
1. City of Johannesburg By Laws for Electrical Connections
2. SANS 10142
3. SANS 959
4. South African Renewable Power Plant Grid Code.
5. NRS 097-2-1 Grid interconnection Generation (Utility interface)
6. NRS 097-2-3 Grid connection of Embedded Generation (Simplified utility connection     criteria for low-voltage connected generators).
7. IEC 62116 Test procedure of islanding prevention measures for utility-interconnected     photovoltaic inverters.
8. IEC 62109-2 Safety of power converters for use in PV power systems –
Part 1: General requirements.
9. IEC 62053-22 Electricity Metering Equipment
10. IEC 60364 – 1 Low Voltage Electricity Installation
A site survey is very important as many installations are done at sites were pre-paid meters are currently installed. No system will be allowed to be connected to a pre-paid meter even if the system will have zero exporting.
The only meter that is currently re-programmable for bi-directional application is Itron. All other meters will need to be replaced. Provided all embedded generated power is legally connected by following the permit application, City Power welcomes grid feeding of all Renewable energy sources.
Acceptance of the plant
Once all commissioning tests have been completed and the installer has issued the relevant COC for the installation, it will be the responsibility of the Installer to notify City Power of the status and request an official commissioning date. City Power will provide a date for their Engineer to visit the site together with the registered PR engineer and the commissioning documents will be signed off simultaneously by both parties at the site.
Embedded Generation Tariff.pdf
COJ Tariff - TOU.pdf

All grid-tied installations, irrespective of the size, have to follow the process outlined by City Power for the Johannesburg metropolitan.
PV system installation in Johannesburg
All City of Johannesburg customers planning for PV system installation should follow the permit application process prior to installation and commissioning of the PV system. It is mandatory for customers with PV systems already installed to follow the same process and register/regularize their installations with the system and connection requirements of City Power.
We advise that all our installers familiarize themselves with the permit application process and hope that the following few point can assist in ensuring responsible supply of world class tier 1 PV equipment.
Applicable standards and guidelines
The technical requirements for Small Scale Embedded Generation are covered in the following standards and guidelines. All installers preparing for an application should ensure compliance with the SSEG standards and guideline indicated below, among other recognized standards:
1. City of Johannesburg By Laws for Electrical Connections
2. SANS 10142
3. SANS 959
4. South African Renewable Power Plant Grid Code.
5. NRS 097-2-1 Grid interconnection Generation (Utility interface)
6. NRS 097-2-3 Grid connection of Embedded Generation (Simplified utility connection     criteria for low-voltage connected generators).
7. IEC 62116 Test procedure of islanding prevention measures for utility-interconnected     photovoltaic inverters.
8. IEC 62109-2 Safety of power converters for use in PV power systems –
Part 1: General requirements.
9. IEC 62053-22 Electricity Metering Equipment
10. IEC 60364 – 1 Low Voltage Electricity Installation
A site survey is very important as many installations are done at sites were pre-paid meters are currently installed. No system will be allowed to be connected to a pre-paid meter even if the system will have zero exporting.
The only meter that is currently re-programmable for bi-directional application is Itron. All other meters will need to be replaced. Provided all embedded generated power is legally connected by following the permit application, City Power welcomes grid feeding of all Renewable energy sources.
Acceptance of the plant
Once all commissioning tests have been completed and the installer has issued the relevant COC for the installation, it will be the responsibility of the Installer to notify City Power of the status and request an official commissioning date. City Power will provide a date for their Engineer to visit the site together with the registered PR engineer and the commissioning documents will be signed off simultaneously by both parties at the site.
Embedded Generation Tariff.pdf
COJ Tariff - TOU.pdf

If you are using 6 panels in series to create 1500w and 220v then you should use a 1500w element and there is no reason not to work, but how will you control the temperature? - if you put 220v DC on your normal geyser thermostat then please DONT tell your insurance broker what you did when the house burns down!!!
You will need a suitable (read heavy duty and very expensive) DC relay to switch the power when the geyser reaches temp - you could use the normal thermostat to control the relay.

I have attached 2 excerpts from latest City Power tariff booklet showing some info regarding grid feedback. It seems that they will allow subject to certain requirements of which this is my interpretation (but I am lazy and prone to error so read the documents for yourself!);
Must be registered install with all usual requirements (which I believe are Nersa requirements so should be similar anywhere), Must be signed off by engineer (also Nersa apparently), Must be a net consumer - you will receive credit not cash, Must be Time Of Use customer - (minimum monthly cost R442.14 + vat = R504.04) Service Fee (all) - R112.02 60A 1ph capacity charge - R330.12 80A 1ph capacity charge - R362.86 60A 3Ph capacity charge - R411.09 80A 3ph capacity charge - R452.03 Summer Rates Peak - R1.3117 Standard - R1.0376 Off Peak - R0.8723 Winter Rates Peak - R3.0177 Standard - R1.2362 Off Peak - R0.8723 Feedback rate (domestic) R0.4279 (same as what Eskom charges City Power) So you must pay a monthly fee of R500 and EXPENSIVE consumption unless you are able to arrange Net zero consumption (so feed back at least 3 times what you consume and much more in winter). Bear in mind that if you are pure grid-tie with no battery backup then your peak morning and evening consumption will be hellish expensive.
I think I am happy to stay without grid-tie using solar during the day (my wife and I both have offices at home so daytime consumption higher than average), and then use Prepaid at night after 20% DOD changeover to grid (battery charging solar only).
Prepaid Service fee - R0 0-500kWh - R1.1357 501-1000kWh - R1.2903 2001-3000kWh - R1.3854 >3000kwh - R1.6961 If I can limit usage to 500kWh I will almost match the monthly connection fees - plus;
much cheaper equipment required, no council loops to jump through, no engineers to please, no-one telling me that I cant add panels without reapplying, and a nice battery bank to carry me through the very regular power failures in our area. ...anyone notice that City Power misspelled [Tarrif > Tariff] in the booklet
 
City Power Booklet_Tariff_2016-2017_Embedded Generation.pdf
City Power Booklet_Tariff_2016-2017_TOU.pdf

Because you are feeding the inverter from an E/L circuit in your grid DB, and you have connected N-E on the outputs which is an earth fault.
I hope the attached sketch is legible, my CAD skills are a touch lacking (I can do it but it will take the whole day!)

Because you are feeding the inverter from an E/L circuit in your grid DB, and you have connected N-E on the outputs which is an earth fault.
I hope the attached sketch is legible, my CAD skills are a touch lacking (I can do it but it will take the whole day!)

Take a look at Annex P.4 starting on page 361 of SANS 10412-1:2017 ed2
I sadly cant share this with you because my scanner has recently croaked and I haven't got around to sorting it out, but in summary you should bond your main E terminal (from earth bar in Main DB) to your inverter N terminal (at the inverter) which will prevent your floating voltage situation. The earth conductor should be a minimum of 50% size of the Live conductors.
This should be done before the inverter output Earth Leakage which I am sure you have installed.
So as an example if you run a 50amp 10mm L/N from the Main DB to your Inverter L/N(in), then you should run at least 6mm from your main E-bar to the inverter body and to the N(out) terminal (looped, not 2 separate wires).

Because the PC at the end of long lead will see rectification sag + cable drop - close pc sees only sag.

I think something like the following is happening;
the PV system is supplying loads and charging batteries, then a high AC load exceeds the inverter happy place causing the system to switch to grid (until the load drops again), the system then dumps the momentary excess PV capacity into the batteries, causing the battery voltage to spike while the MPPT adjusts to the lower requirement. I wouldn't be too concerned until you see smoke.

I think there are a few points deserving comment here:
1. It is not good practice to add new lead acid batteries to an existing used bank.  Batteries age both with time as well as with discharge cycles, and as they do, they take, hold and deliver energy at a decreasing rate. Adding a bank of fresh batteries in parallel with your existing ones will result in disparate charging between the two.  This can be managed to a degree, but is not ideal.  Top quality flooded batteries like Trojans are apparently less susceptible to this than your typical SLA or AGM block. This, incidentally, is one of lithium's great advantages - you can pretty-much add capacity whenever you like, as the BMSs manage the batteries at cell-level.
2. For a backup application, you need to pay attention to the "C" rating of your battery - this tells you how much energy you will get out of the battery at a particular rate of discharge.  Most lead acid batteries are rated at C10, some at C20 - in other words, a 100Ah (C10) battery will be able to give you 100Ah of energy when discharges over 10 hours WHEN NEW.  For a power backup application, and in particular load shedding, we are typically looking at a 2-3 hour backup requirement.  A typical 100Ah AGM battery would have a C3 rating of 80Ah. Most lithium batteries are rated at C1, but warranty requirements may limit use to C2, which is still fine.
3. Whilst the economics of total energy of Lithium is a clear winner, you need to be aware of your maximum power requirements.  The greater discharge depth of lithium allow a smaller battery to be utilised, but there is a limit to the continuous maximum power that can be drawn.  For example, the Pylon 3.5kWh battery coupled to an Axpert inverter (no communication) must be limited to a 37A (1.75kW) continuous discharge rate, to comply with warranty conditions. If you have a larger capacity inverter you can control this by installing a suitably rated circuit breaker on the inverter output (effectively de-rating the inverter), which can be increased at a later stage if you decide to add more battery.
3.As @DaveSA indicated, you need to decide whether you intend to cycle your batteries.  In brief, if you want to make use of your solar panels, you need to cycle the batteries.  If you intend to cycle, you need to go lithium. It's as simple as that, if you have grid power.  There is no lead acid battery which offers a warranted cost/kWh which is cheaper than grid power.
In summary, I would recommend lithium over lead acid in all but the most basic backup setups, assuming budget allows, the inverter is compatible, and you are sure of your energy and power requirements.  Its also useful to remember that you will be comparing capacities of the various batteries when new, but due to the significantly longer cycle life of lithium, the difference in usable energy after a year or two can become increasing disparate in lithium's favour.
Enjoy!
 

So I popped over to the Megasolar web site and scrolled down to latest news where I found this;
http://www.megasolarsa.com/nuclear-vs-renewable/
Huh is that not a blog by Jason Sole - the one and only who has nothing to do with Megasolar???
So if you rob a bank and then change your name, are you no longer a bank robber?

@Pilotfish, CoJ's piddly tariff is about as good as it gets. In march 2017 Tshwane's Mayor Solly Msimang got up on his soap box and waxed lyrical about Tshwane becoming the "solar capital of South Africa" - this from a municipality that it unable to even publish its electricity tariffs until midway through the financial year.  NERSA has subsequently approved a 10c/kWh FIT ("Credit reverse energy charge") for Tshwane (yes, that's not a typo, 10 cents per kWh), so once you have parted with the necessary "Access Charge" it is simply impossible for residential-scale rooftop PV to break even. http://www.nersa.org.za/Admin/Document/Editor/file/Electricity/PricingandTariffs/201819/Gauteng Province - Approved tariffs.pdf
Our electricity supply bodies are by-and-large a disgrace.  They are unable to get the basics right (billing, maintenance, tariff design) - we should not hold our breath waiting for meaningful FITs to improve the economics of rooftop solar.
I believe we may see yet another technology leap-frog in this regard: the improving economics of energy storage present an opportunity to focus solar system designs around self-consumption optimisation (with inherent power security benefits in the face of unreliable electricity supply).

[Joburg] In order to access the piddly feed in tariff of 42.79c/kWh you will need to jump through various hoops of diminishing diameter in order to register as SSEG, and then you will be forced to migrate to Time Of Use metering - with very high monthly fixed cost of R400-R500/m before any power consumed, and very high power costs when you need it and low power costs when you dont need it.
It is just not worth it, which is by design by City Power because they dont want high earners (reliable payers) installing PV systems, they need the money for cross subsidies.
COJ Tariff - TOU.pdf
Embedded Generation Tariff.pdf

That would be the best way forward if in the budget.

Replace and carry on - fuses will often blow at lower than rated currents as a result of heat build up from other sources. Make sure your terminals are tight, wire not too thin or annealed, fuse terminal gripping tightly.

[Joburg] In order to access the piddly feed in tariff of 42.79c/kWh you will need to jump through various hoops of diminishing diameter in order to register as SSEG, and then you will be forced to migrate to Time Of Use metering - with very high monthly fixed cost of R400-R500/m before any power consumed, and very high power costs when you need it and low power costs when you dont need it.
It is just not worth it, which is by design by City Power because they dont want high earners (reliable payers) installing PV systems, they need the money for cross subsidies.
COJ Tariff - TOU.pdf
Embedded Generation Tariff.pdf

1. What is your max AC demand (A) on your inverter circuit. - 36 amps/2 (18 amps per inverter)
2. What is the max AC demand (A) at your grid connection. - seldom exceeds 50 amps (in Winter)
3. What is the max DC demand from the batterys - never exceeds 166amps (4kW per inverter)
4. What is the max charging current you allow from each inverter. - 40amps each (80a total)
5. What is your total amps on your PV side. - 40amps per inverter (midday spring)
6. If you feed back to grid, What is the max (A or Watts) you export. - I don't
October kWh - total consumption 909 / Grid consumption 143 / PV production 882

There is no rocket science to what I am planning, I intend using a contactor with 2x n/o and 2x n/c contacts to perform the changeover role currently performed by the Axpert, thereby allowing my system to be classified as off-grid instead of the bogus grid-tied classification they currently choose to apply.


With the above arrangement there will be no point where the Axpert setup comes into contact with the grid. I understand that I may have to register as an SSEG (eventually), but as an off-grid setup there will be no dealing with ineffective council, no tariff changes and no engineer sign-off, I will do my own COC.
I dont want to go the route suggested by TTT because I am currently on prepaid and average about R250/m over the year at a low unit cost because of my low usage - the moment I am classed as grid-tied I will attract a high monthly connection fee, higher unit costs, and jump through various impossibly tight hoops - no thanks, I HATE red tape!
The perceived downside is that I wont have grid charge available, but I charge solar only so if the C/O is successful it will have zero effect on my current situation which is very effective.
The only "development" that I need to do is to try and get a changeover setup that will allow the operation without affecting PC's/TV;s/Decoder/Amps etc - failing which I will need to install UPS's which I am trying to avoid. I was hoping to do some experimentation this weekend but life intervened.

I think it has to do with a short developing in one cell of one string. Now the other strings are dumping current into this string because it is now at a lower potential. In particularly severe cases -- and one can probably debate how likely that is but I'd expect from three strings upwards it becomes quite possible -- you could be cooking and heating batteries in that bad string. It would be better if there was a fuse that could disconnect just that one string. That's the idea at least, the theory.
In a BYD rack for example, each module has a 85A breaker, but the rack as a whole would have another 125A breaker. Same idea :-)
Victron has a busbar system with individual fuses for exactly this kind of setup. Of course it isn't exactly cheap, but it explains the general idea. Jono modifies a "Battery In" unit here, from around 7:00, to use fuses. There is also a distributor module that also has LEDs to show blown fuses.