There was a declaration by the president that overruled this.

 From SAP     Import            Export

Oct 23	520.794	1,256.083
Nov 23	452.996	1,192.301
'Dec 23	381.076	1,833.817
‘Jan 24	342.252	1,967.088
Feb 24	365.277	1,735.952
'March 24	441.691	1,724.778
'April 24	520.181	1,138.854
May 24	629.939	962.096
June 24	639.060	685.092

Edited June 13, 20242 yr by NoJ

4 hours ago, GreenFields said:

It's the other way around - @macafrican is saying that at the Eskom customers WITHOUT solar are currently paying on behalf of the people that DO have solar.

The old tariff structures were fine when nobody was using solar, but now more and more solar is buggering up the assumptions that are underlying the old billing.

The point is, the true cost is made up of a fixed rate for the infrastructure before you've even used a single unit, and a variable rate for burning coal to produce power. This is what is charged to your municipality by Eskom. However, the municipality in turn was always charging the individual households NO fixed charges, and everyone the same fee per unit, probably for simplicity. If everybody keeps buying from Eskom, the billing models make sense. But when Solar users are buying for example just 10 units per month, then they are not buying enough units anymore to cover the fixed charges of maintaining the grid. That cost then falls to the remaining people that are still buying around 600 or whatever units. That's the less bad scenario when at least folks are using batteries.

A further problem, on top of that, and that's the case here, there's the issue that it costs Eskom differently at different times of the day to generate power, low-cost during the night and most of the day when generating from coal, and a much higher cost during peak time when they have to run expensive gas and diesel peaker plants. Let's say - just making up the numbers for illustration but it's not far off - that it costs 80c per unit to produce power at noon, and R8,00 per unit to produce power at 6pm - as long as people are paying around R2.68-R3.71 all around the clock, it sort of works out. You "overpay" at noon, and you "underpay" at 6pm but on average it's fair. Now what happens with solar is that people are not paying anything during the day anymore, but at night they want to buy the most expensive power at below the cost of generation. The utility can only lose like that. Not just losing out on sales, but actively losing money that other customers must somehow cough up for. And the solar user is either oblivious, or doesn't care, and gets indignant about it, as if buying solar power gives him a right to do what he wants when he wants no matter the costs to others.

Just in principle, the only fair way is to start passing on the billing to the end user in the same way as the municipality gets billed by Eskom. A fixed rate, combined with a time-of-use billing, including also a time-appropriate rate for selling into the grid. At appropriate corruption-free price levels, whatever that may be. And it does change the economics around choosing the right solar system if you're buying new, and it screws up the assumptions you may have had if you've already bought.

 

 

Maths is wrong

 

Edited June 13, 20242 yr by NoJ

13 hours ago, NoJ said:

No 30KW inverters I have more than 30KW solar panels and it is for my HOUSE.  Soon I will add another 30KW plus.  Iw ill stop when I have about 65KW that I can push back

 

 

NO!!    If you have more than 4.6kVA per phase exporting to the grid, you are entirely in breach of NR097:2:2023.    In summary, small scale embedded generation on a shared low voltage feeder must not, for technical reasons, exceed 4.6kVA per phase.   Those rules go back a decade.

what I have seen allowed:

if your council says it is 4.6kVA at dc level, they are wrong, the regulation refers to AC export not DC generated.   So you can argue that 5.5 solar is 4.6 ac.

if your council is progressive, they will allow you to install a lot of solar as long as your inverter is limited to export no more than 13.8kVA three phase and at unity.

what some people do is split their AC into a public db and a private db.    Nobody has any say over how much solar you install that sees a private db with loads that see that private db.     You can then still do the 4.6 per phase on your public db and many guys put the battery bank shared as that counts as pure isolation between the private and public board.    You will be fine if the inverters on private db can not in any way export AC to grid.

this will also be a trick when tariffs get rebooted.     So you do the split and downgrade your public db to the smallest available in your council residential  tariff, thereby paying for say a 20A public connection even if you have 150A private db with very big solar.      You leave a 20A charger on the public board that only gets activated when you really need grid.

 

 

9 minutes ago, macafrican said:

NO!!    If you have more than 4.6kVA per phase exporting to the grid, you are entirely in breach of NR097:2:2023.    In summary, small scale embedded generation on a shared low voltage feeder must not, for technical reasons, exceed 4.6kVA per phase.   Those rules go back a decade.

what I have seen allowed:

if your council says it is 4.6kVA at dc level, they are wrong, the regulation refers to AC export not DC generated.   So you can argue that 5.5 solar is 4.6 ac.

if your council is progressive, they will allow you to install a lot of solar as long as your inverter is limited to export no more than 13.8kVA three phase and at unity.

what some people do is split their AC into a public db and a private db.    Nobody has any say over how much solar you install that sees a private db with loads that see that private db.     You can then still do the 4.6 per phase on your public db and many guys put the battery bank shared as that counts as pure isolation between the private and public board.    You will be fine if the inverters on private db can not in any way export AC to grid.

this will also be a trick when tariffs get rebooted.     So you do the split and downgrade your public db to the smallest available in your council residential  tariff, thereby paying for say a 20A public connection even if you have 150A private db with very big solar.      You leave a 20A charger on the public board that only gets activated when you really need grid.

 

 

There has been a proclamation by Mr  Ramaphosa that changed everything.

The technical reason is total nonsense. 

Since when does a breaker or a cable or a transformer know which way current is flowing?

This was my excess for Jan 2024. On the 8'th I pushed back 76KWhr for the day. Do the maths.

This been covered in previous discussions. Come summer I will push back about 130KW per day

26 minutes ago, NoJ said:

There has been a proclamation by Mr  Ramaphosa that changed everything.

The technical reason is total nonsense. 

Since when does a breaker or a cable or a transformer know which way current is flowing?

This was my excess for Jan 2024. On the 8'th I pushed back 76KWhr for the day. Do the maths.

This been covered in previous discussions. Come summer I will push back about 130KW per day

The presidential proclamation was about limits lifted to 100MW for very big systems.

I am MV connected to the grid through my private MV:LV transformer so I could go big solar.

You are LV connected to the grid, could be single phase or three phase.     There are very good technical reasons from grid perspective why people on a shared LV feeder (you and say 100 houses around you are connected to one MV:LV transformer) should be individually subject to limits.    You can go read NRS97:2 and argue with them if you disagree.     At a more practical level, you will have an instant disaster if you try and connect 65kW solar on a 60A single phase connection!

35 minutes ago, NoJ said:

There has been a proclamation by Mr  Ramaphosa that changed everything.

The technical reason is total nonsense. 

Since when does a breaker or a cable or a transformer know which way current is flowing?

This was my excess for Jan 2024. On the 8'th I pushed back 76KWhr for the day. Do the maths.

This been covered in previous discussions. Come summer I will push back about 130KW per day

I see where we are missing each other : you are confusing kW and kWh

You said “No 30KW inverters I have more than 30KW solar panels and it is for my HOUSE.  Soon I will add another 30KW plus.  Iw ill stop when I have about 65KW that I can push back”

What you meant is you want to push back 65kWh per day.     That would mean a three phase home with about 12kW worth of solar capacity in CPT in summaer and not using much in terms of loads.     A 65kW solar system would be outputting 350kWh+ per day.

If you are three-phase connected you can legally and safely do around 16kWdc solar even if COCT argues that the limit is 13.8kWdc.    You could do say 25kWdc and convince them that your inverter will throttle grid export at 13.8kWac.   That way your loads get solar and you export the most solar you are legally allowed to.

 

 

 

We have been through this already on this site.

 

So help me with my maths. Help me understand what am I calculating wrong.

I had 16KW in Jan produced about 2MW feedback.  Do understand 16KW inverter or  16000/240 = 66Amps AC or alternating current NOT DC.
Now I am busy with another 14KW inverter power that means I will add another +/- 2MW monthly or +/- 14000/240 = 58Amps.
Then when my building is complete I will add another 30KW or 30000/240 = 124 Amps. Thus in summer if I understand maths correctly 32000 + 30000 = 62 KW  or  62000/240 = 258 Amps.

January I generated about 110KW per day of which +/- 70KW per day was pushed back.  Some day's more some day's less depending on the sun.

Where is my calculations wrong?  Can you please help me with my maths that I can understand what I am calculating incorrectly.  I currently have more than 40 panels installed. 

Below is an account print out. My calculations differ as I work per calendar month and the council has a moving month for billing on the water you can see it is 33 days.

Maybe you can explain to me what I do not understand and where I error with my calculation.  My calculations are not scientifically correct to the 3rd decimal but it is accurate enough for me to understand:

1. My new 14Kw inverters is already paid for
2. The existing 16KW is paid for
3. All panels are paid for.
4. My electricity pays my taxes on my house and my water is free as I use an RO for sea water.

Please help me understand where I error.

 

Thank you

Edited June 14, 20242 yr by NoJ

38 minutes ago, NoJ said:

We have been through this already on this site.

 

So help me with my maths. Help me understand what am I calculating wrong.

I had 16KW in Jan produced about 2MW feedback.  Do understand 16KW inverter or  16000/240 = 66Amps AC or alternating current NOT DC.
Now I am busy with another 14KW inverter power that means I will add another +/- 2MW monthly or +/- 14000/240 = 58Amps.
Then when my building is complete I will add another 30KW or 30000/240 = 124 Amps. Thus in summer if I understand maths correctly 32000 + 30000 = 62 KW  or  62000/240 = 258 Amps.

January I generated about 110KW per day of which +/- 70KW per day was pushed back.  Some day's more some day's less depending on the sun.

Where is my calculations wrong?  Can you please help me with my maths that I can understand what I am calculating incorrectly.  I currently have more than 40 panels installed. 

Below is an account print out. My calculations differ as I work per calendar month and the council has a moving month for billing on the water you can see it is 33 days.

Maybe you can explain to me what I do not understand and where I error with my calculation.  My calculations are not scientifically correct to the 3rd decimal but it is accurate enough for me to understand:

1. My new 14Kw inverters is already paid for
2. The existing 16KW is paid for
3. All panels are paid for.
4. My electricity pays my taxes on my house and my water is free as I use an RO for sea water.

Please help me understand where I error.

 

Thank you

Maybe start with confirming what exactly is your grid supply size, or what size circuit breaker have you got? Probably not a single-phase 60A circuit breaker. 80A? 3-phase? Rating per phase? Is it typical of the average household?

Your breaker might not care which way the power flows, but it might care if you exceed its rated current.

3 phase 100A per phase.  I thought for those that understand the maths it would have been commonsense.

Edited June 14, 20242 yr by NoJ

You’re confusing kW and kWh.     KW is power, kWh is energy over time.     Think of it like water in a pipe.   You have a 10cm pipe (10kW) that delivers 10 liters per hour (10kWh).  After three hours you have 30 liters (30 kWh) but obv still have a 10cm pipe.   With solar, that 10cm pipe has low pressure in the morning and it might only deliver 2 liters per hour at that time.

You take your solar DC capacity (sum of adding the watts of all your panels) is say 16000 Watts.   That might have for example a 18kW grid tied inverter.

Over a year unless you have odd tree or mountain shade, you should expect around 1525h of output at AC level.    16kW * 1525h = 24,400 kWh.   That will not be linear over year.   For rough math work on 6.1h per day in summer and say 2.6 in winter.   You can use these ‘solar hours’ and ignore that your 16kw system is only doing 1kw at 8AM and 1.8kWh between 8AM and 9AM and it might do 17kW on a cool sunny day.      Solar hours are basically a conversion of the solar exposure per sqm and the 1525h I gave you is based on what I’ve seen across many MW in the area and is measured after conversion, so it is your alternating current hours.  Forget about the DC Watt hours and conversion losses - solar hours the way I gather them is your AC output to expect.

If you switched off all your loads then you’d be generating about 3MWh in Dec/Jan in Cape summer (16kW x 6.1h x 31days).   In Winter generating about 1.3MWh in July.

What you export is entirely a function of generation and your loads and the timing of your loads.    If you add more solar then the added solar is likely to nearly all be added to exports because your old solar export was after loads deducted.   Despite all the theory, if you can, try and do your new solar that a portion faces ENE, a portion N, and a portion WNW.    What you lose in solar hours vs all North is minor compared to the benefit of a longer flatter kWh curve.     Think of it this way : with a longer flatter curve you get more solar earlier, and later, even if you export less in middle of day.

As mentioned, you CANNOT add more in conventional grid-tied solar if you are LV connected on a shared LV feeder which I am 99% certain you are.    There are rural connections where one client is on one pole mount transformer and he can do different.   You cannot, COCT can detect you in an instant and importantly your AC setup might not cope with 30kW which is say 150Amps!   Very few homes are wired for that.   What you could do is split your AC board.    So put more solar down, this time put a hybrid inverter with that new solar and add a battery bank and move everything that you would like to have backed up during loadshed/power failure onto this second DB.      Your other AC board has the loads that will go down if grid goes down and it has your existing solar and it will export when old solar exceeds the loads that stayed on the public board.    So it will prob export more and depending how you size your private AC board and what you put on it in terms of loads, that would never export to council but always have 3 to 5 hours of stored energy.   (There are cheat methods that if your private AC board and new solar has full battery to supply some of that DC to your old grid-tied inverter but now getting very tricky.      You would add a small breaker in your public AC board and program the new hybrid inverter on your private AC board to (1) only charge the battery (2) at a throttled kW and (3) not export to grid and (4) only when that battery is in trouble say 20% SoC.    You could cheat a bit and allow export after battery full but be careful to cap that at what the public AC board’s middle of day loads are.     You mentioned your new inverter is paid for : if I were you I would really ask the guys if you can upgrade that to a hybrid inverter and add batteries.     You have so much solar, you really should have all lights and plugs at minimum able to run almost indefinitely.    You will go insane if you have 30kW residential solar and no power during grid problems.

21 minutes ago, NoJ said:

3 phase 100A per phase.  I thought for those that understand the maths it would have been commonsense.

Hell guy, don’t insult people trying to help you.   Especially when you were confusing kW and kWh!   Obviously they’ll start at the bottom to figure what you actually have

16 minutes ago, macafrican said:

Hell guy, don’t insult people trying to help you.   Especially when you were confusing kW and kWh!   Obviously they’ll start at the bottom to figure what you actually have

Don't waste your time arguing with this guy. NoJ was previously Erastus, who left the forum because people could not understand what he was trying to say, and he could not understand what people were saying to him.

Edited June 14, 20242 yr by P1000

28 minutes ago, macafrican said:

Hell guy, don’t insult people trying to help you.   Especially when you were confusing kW and kWh!   Obviously they’ll start at the bottom to figure what you actually have

Thanks, but relax, I'm easy. More bemused than offended.

51 minutes ago, NoJ said:

3 phase 100A per phase.  I thought for those that understand the maths it would have been commonsense.

Look, if one follows the NRS 097 guideline, then your 3-phase 100A supply should be capped at 17kW export capability, which is around 25% of the 69kW maximum power on that line. This is already being exceeded with the existing 30kW installed.

Going out on a limb and saying this is clearly not the average size home supply. You've obviously already calculated that you can add another 30kW to get closer to the peak power rating of the supply line, you'll have around 86% of peak capacity connected. Just bear in mind that you can probably just carry 23kW per phase, so you may have to re-consider onto which phase you install which additional inverter(s).

Honestly I don't know whether CoCT has dispensed with NRS 097 just because they want to buy every last kWh they can. Maybe you should ask them that in writing before proceeding.

Lastly, I don't deal in precise maths, only in rough 2c's worth, some high-level thumbsucks, a couple of estimates, and I'll leave it to you and your installer to sort out the details about installing that much power in your home with CoCT.

 

Edited June 14, 20242 yr by GreenFields

2 hours ago, macafrican said:

You’re confusing kW and kWh.     KW is power, kWh is energy over time.     Think of it like water in a pipe.   You have a 10cm pipe (10kW) that delivers 10 liters per hour (10kWh).  After three hours you have 30 liters (30 kWh) but obv still have a 10cm pipe.   With solar, that 10cm pipe has low pressure in the morning and it might only deliver 2 liters per hour at that time.

You take your solar DC capacity (sum of adding the watts of all your panels) is say 16000 Watts.   That might have for example a 18kW grid tied inverter.

Over a year unless you have odd tree or mountain shade, you should expect around 1525h of output at AC level.    16kW * 1525h = 24,400 kWh.   That will not be linear over year.   For rough math work on 6.1h per day in summer and say 2.6 in winter.   You can use these ‘solar hours’ and ignore that your 16kw system is only doing 1kw at 8AM and 1.8kWh between 8AM and 9AM and it might do 17kW on a cool sunny day.      Solar hours are basically a conversion of the solar exposure per sqm and the 1525h I gave you is based on what I’ve seen across many MW in the area and is measured after conversion, so it is your alternating current hours.  Forget about the DC Watt hours and conversion losses - solar hours the way I gather them is your AC output to expect.

If you switched off all your loads then you’d be generating about 3MWh in Dec/Jan in Cape summer (16kW x 6.1h x 31days).   In Winter generating about 1.3MWh in July.

What you export is entirely a function of generation and your loads and the timing of your loads.    If you add more solar then the added solar is likely to nearly all be added to exports because your old solar export was after loads deducted.   Despite all the theory, if you can, try and do your new solar that a portion faces ENE, a portion N, and a portion WNW.    What you lose in solar hours vs all North is minor compared to the benefit of a longer flatter kWh curve.     Think of it this way : with a longer flatter curve you get more solar earlier, and later, even if you export less in middle of day.

As mentioned, you CANNOT add more in conventional grid-tied solar if you are LV connected on a shared LV feeder which I am 99% certain you are.    There are rural connections where one client is on one pole mount transformer and he can do different.   You cannot, COCT can detect you in an instant and importantly your AC setup might not cope with 30kW which is say 150Amps!   Very few homes are wired for that.   What you could do is split your AC board.    So put more solar down, this time put a hybrid inverter with that new solar and add a battery bank and move everything that you would like to have backed up during loadshed/power failure onto this second DB.      Your other AC board has the loads that will go down if grid goes down and it has your existing solar and it will export when old solar exceeds the loads that stayed on the public board.    So it will prob export more and depending how you size your private AC board and what you put on it in terms of loads, that would never export to council but always have 3 to 5 hours of stored energy.   (There are cheat methods that if your private AC board and new solar has full battery to supply some of that DC to your old grid-tied inverter but now getting very tricky.      You would add a small breaker in your public AC board and program the new hybrid inverter on your private AC board to (1) only charge the battery (2) at a throttled kW and (3) not export to grid and (4) only when that battery is in trouble say 20% SoC.    You could cheat a bit and allow export after battery full but be careful to cap that at what the public AC board’s middle of day loads are.     You mentioned your new inverter is paid for : if I were you I would really ask the guys if you can upgrade that to a hybrid inverter and add batteries.     You have so much solar, you really should have all lights and plugs at minimum able to run almost indefinitely.    You will go insane if you have 30kW residential solar and no power during grid problems.

Just so you know and understand I design and develop control system for a living.

So I will stress about power if I get to 300KW.  Below that its lego blocks.

2 hours ago, GreenFields said:

Thanks, but relax, I'm easy. More bemused than offended.

Look, if one follows the NRS 097 guideline, then your 3-phase 100A supply should be capped at 17kW export capability, which is around 25% of the 69kW maximum power on that line. This is already being exceeded with the existing 30kW installed.

Going out on a limb and saying this is clearly not the average size home supply. You've obviously already calculated that you can add another 30kW to get closer to the peak power rating of the supply line, you'll have around 86% of peak capacity connected. Just bear in mind that you can probably just carry 23kW per phase, so you may have to re-consider onto which phase you install which additional inverter(s).

Honestly I don't know whether CoCT has dispensed with NRS 097 just because they want to buy every last kWh they can. Maybe you should ask them that in writing before proceeding.

Lastly, I don't deal in precise maths, only in rough 2c's worth, some high-level thumbsucks, a couple of estimates, and I'll leave it to you and your installer to sort out the details about installing that much power in your home with CoCT.

 

Oh dear me that has been recalled. Then mayor Lewis had a long speech on this. Since then things changed.  The COCT is on the fore front with this and people has a difficulty to understand what is happening.  I think the account I showed one can clearly see that I generate more than 2MW per month.

That NRS guide line is of no value.  When I have the next 15KW working properly in the summer I will send you the graphs. I am 100% in the frame work set by President Ramaphosa and Mayor Lewis.

The cash back of R15K since Nov I think is proof of it.

I think the challenge is going to come when I want to exceed 300A push back.   😇

Edited June 14, 20242 yr by NoJ

2 hours ago, P1000 said:

Don't waste your time arguing with this guy. NoJ was previously Erastus, who left the forum because people could not understand what he was trying to say, and he could not understand what people were saying to him.

'n Goeie begryper het 'n halwe woord nodig.  Ek kan nier help as mense nie somme kan maak nie en aanvaar dat almal tegnies gestremd is nie

Basies is ek te lui om detail te bespreek.

Wat belangrik is is 'n Goeie begryper het 'n halwe woord nodig.

As mense nie die berekeninge kan verstaan nie is ek nie daar om dit te leer nie.

Ek argumenteer nie ek wys net uit hoe beperk mense se denke is

Let me add one sentence.  Show me where any person could prove the calculations wrong, the installation cost or where any entity had legal issue.

Surely if no person can proof the calculations wrong and the fact that you can see the impact on my account then you must be very dumb to argue against facts.

My calculations are good, my savings are terrific, my expansion on solar is what every one tell me can't be done yet I show it on my account and then you say I am arguing.

Meditate on it and then you consider who needs to be convinced. 

I assure you not me.

I smile all the way and the people I have guided what to do so do they and frankly as for the rest you are most welcome to support Eskom and the corrupt. 

Edited June 14, 20242 yr by NoJ