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When does it become viable to install solar power


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1 hour ago, Richard Mackay said:

My gut feeling is the same. Why we can't get clarity on these issues is amazing. The industry produces sophisticated grid tie inverters to assist with distributed power generation. Yes, this does become a problem when there is a massive uptake in these systems (mostly driven by incentives) but there's no way this can be the reason here in SA. 

Maybe the authorities are paranoid about something that might happen one day??

I still don't understand the uptake reasoning. With an inverter my uptake is less after a blackout than someone else without an inverter.

The duck curve power demand is a bigger problem in my mind.  They don't want our power during the day when you have sunlight.

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Hi I am busy installing a 8kw Sunsynk Hybrid Parity (Super) Inverter which allows you to divert the excess power to non essential loads in a split DB without feeding back to the grid or changing

When does it become viable?  In short my answer is it never does.  But: - The larger your electricity use the larger your system need to be thus your return on investment stays similar - It doe

You don't say where you are, but no matter: We should all know where our meters are and read them. Even if you don't read the same day as the municipality you can check your bill, see the read date an

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13 hours ago, Gerrie said:

I experienced this problem because I normally run completely off-grid during the day, so my prepaid display in my home would be fed from solar power during the day when my system switch over to solar, and that caused lost comms with the outside meter at the utility kiosk. I ended up moving the prepaid display to my utility main breaker that now works very nice as it is illuminated when Eskom is on and when it is off I know there is no Eskom power.

I currently have my meter on the closest plug to the main breaker on the upstream side of the inverter. 

How do you legally connect it to the mains breaker?  Can I install a wall plug next to the DB fed directly from the mains breaker?

Anyway, I suspect it is the current transformer around the mains incoming line connected to the goodwe inverter that is giving disturbances.  Could that be?

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2 hours ago, Richard Mackay said:

My gut feeling is the same. Why we can't get clarity on these issues is amazing. The industry produces sophisticated grid tie inverters to assist with distributed power generation. Yes, this does become a problem when there is a massive uptake in these systems (mostly driven by incentives) but there's no way this can be the reason here in SA. 

Maybe the authorities are paranoid about something that might happen one day??

Well I'm no electrical engineer, just a common or garden computer programmer *, so I figure there is some reason that I don't understand and that an electrical engineer might. I think I've seen on this forum that in CT there is some factor that is applied as a limit to what you can install, and I've read several times that in some parts of Australia they have problems because they can have too much power on the grid (or a local segment thereof) during the day and then suddenly they have a large nett load as the sun starts going down.

Maybe it's just as simple as electricity being a revenue generator (pardon the pun) and so whilst they can't stop you having solar they can make it expensive for you to be in a position where they start paying you rather than the other way around.



* And I know my place. I used to work for a big healthcare group and in the IT department we used to have a little joke: 
Q: What's the difference between a neuro surgeon and a computer progammer?
A: The programmer knows he doesn't know anything about brain surgery.

Edited by Bobster
joke ha ha ha
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28 minutes ago, Pietpower said:

How do you legally connect it to the mains breaker?  Can I install a wall plug next to the DB fed directly from the mains breaker?

My prepaid meter worked great for more than 3years than I got new neighbours who installed electric fencing and than problems started, I had a problem for more than a year that when I tried to load prepaid units my meter would not except the newly purchased tokens, after calling the municipality the municipal electricians would come over take the keypad directly to the municipal mains breaker, connect it there and it would load units the first time, After about a dozen of times of coming out they had enough so they installed a socket outlet directly below my main breaker no earth leakage. They said in future I must just load it there myself.

It was a nuisance as I sometimes had to go out at night with a torch, keypad and voucher number to load units, So what I done is cut off the plug top and installed a small 6A circuit breaker next to the main municipal breaker and feed my keypad directly from there, Fortunately this is just on the outside of my bedroom wall so I drilled through the wall the keypad now inside my room but connected directly outside. Legally wise, I think its ok now with the 6A breaker a bit safer than the loose hanging socket these guys gave me as a quick fix🙂

(By the way this is a Landis and Geyer prepaid meter, I heard they are known for this funny behavior)

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10 hours ago, Bobster said:

Well I'm no electrical engineer, just a common or garden computer programmer *, so I figure there is some reason that I don't understand and that an electrical engineer might. I think I've seen on this forum that in CT there is some factor that is applied as a limit to what you can install, and I've read several times that in some parts of Australia they have problems because they can have too much power on the grid (or a local segment thereof) during the day and then suddenly they have a large nett load as the sun starts going down.

On a lighter note I had the dubious pleasure last year of being on a cruise in the Adriatic with the rest of the passengers being Aussies.
The only subject that I found interesting was their RE systems. Many of them had installed solar PV systems driven by incentives offered by the utilities. The first programs were generous when PV was new. As more systems were installed so the initiatives (feed in tariff) reduced.
The utilities continue to honour all the programs as long as no modifications are made to your system. So the owners never upgrade their systems because the initial FIT was so generous.

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Hi

I am busy installing a 8kw Sunsynk Hybrid Parity (Super) Inverter which allows you to divert the excess power to non essential loads in a split DB without feeding back to the grid or changing the wiring. This is achieved by installing a ct at the municipal feed  input in  the db. It will divert the excess power to non essential loads and can be adjusted. Geysers, pool pumps etc. can utilize this excess power. The explanation for this that the inverter drops the voltage just enough not to feed back by checking the reverse current from the ct.

It will not trip of interfere  with any prepaid meter. This is a great feature for those with prepaid meters problems. It can also feed back to the grid without a prepaid meter.

Edited by Peter Topp
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12 hours ago, Peter Topp said:

It will not trip of interfere  with any prepaid meter. This is a great feature for those with prepaid meters problems. It can also feed back to the grid without a prepaid meter.

This is not 100% true. Depending on your type of meter, it might still trip it. The inverter attempts to stop the feedback, but in certain cases it is not fast enough, or the meter is too sensitive. This can happen when you have a big load that is being powered from solar, and the load suddenly switches off. For example if you're feeding in 3.5kW from your solar panels into your geyser (non essential / non-backed up circuit), and the geyser switches off, the inverter can't instantly stop PV production, it takes a couple of milliseconds. During this time a little bit of current will flow into the grid.

 

I have the same setup that you're describing, with the Sunsynk 5kW inverter. My meter is a Landis Gyr 5235A. I am in a complex so I can't feed back. This meter doesn't trip with feedback, it just displays an error. The display on mine alternates between the kWh reading and a message that says "rED", aka reverse energy detected. So in my case it is not a problem, but a prepaid meter might have tripped.

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Hi Bernarf

I totally agree. The reason for the the feedback will be because when you switch off a large load suddenly the voltage may increase slightly and the inverter needs a small amount of time to adjust. I have not test my inverter yet. I also believe from the videos from the web sight that some prepaid meters allows a small  amount of feedback (80w max)

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15 hours ago, Peter Topp said:

Hi

I am busy installing a 8kw Sunsynk Hybrid Parity (Super) Inverter which allows you to divert the excess power to non essential loads in a split DB without feeding back to the grid or changing the wiring. This is achieved by installing a ct at the municipal feed  input in  the db. It will divert the excess power to non essential loads and can be adjusted. Geysers, pool pumps etc. can utilize this excess power. The explanation for this that the inverter drops the voltage just enough not to feed back by checking the reverse current from the ct.

It will not trip of interfere  with any prepaid meter. This is a great feature for those with prepaid meters problems. It can also feed back to the grid without a prepaid meter.

My Goodwe feeds excess power (when it's available) to non essential loads, but only whilst the grid is available. 

I think that feature is not uncommon, but it does annoy me that on a gloriously sunny day with solar power up the wazoo and fully charged batteries I can't run my pool pump if there's a power outage.

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IT seems from what I read ... the problem is the grid feedback ... and I need as many solar panels as I can afford.

What if I chat to my neighbours and get them to buy into the system ...for example ...rather than feeding back into the grid ...excess electricity can be redirected to the 4 houses around my house ... via an electricity meter to each property.

I am also thinking ... maybe install another 200 liter geyser ... seal up the geyser and lag all the piping ... then i turn up the thermostat to max ( I think around 65/70 degrees) and makes sure when there is no solar power ... the geyser is off.

I have a gas stove ... so there is never a problem with heating water ... cooking ...coffee etc ... man going gas on the stove is a life saver ... I am also considering a gas geyser.

 

 

 

 

 

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26 minutes ago, isetech said:

IT seems from what I read ... the problem is the grid feedback ... and I need as many solar panels as I can afford.

What if I chat to my neighbours and get them to buy into the system ...for example ...rather than feeding back into the grid ...excess electricity can be redirected to the 4 houses around my house ... via an electricity meter to each property

Yee-Haaa! This is called a microgrid. If you can get it right let us know how you did it!

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Hi

I want to clarify the the statement that I motioned about grid feedback. I have now completed my install with a Sunsynk 8KW Hybrid inverter. After going through all the documents and videos this is what I have got from them. You can achieve Zero feedback to grid even with large load switching. Sunsynke, Inga and  Deye have fixed this problem by doing the following. They have got a setting ( Zero Export Power) that will allow you set a watt value that allows the grid to give a small amount of power when you are using using pv power. This will raise the voltage a small amount good enough so that the switching off of large loads will not affect the feedback into prepaid meters. The bigger the load the higher the grid watts needs to be set to avoid feedback. Very, very nifty.

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8 hours ago, Peter Topp said:

Hi

I want to clarify the the statement that I motioned about grid feedback. I have now completed my install with a Sunsynk 8KW Hybrid inverter. After going through all the documents and videos this is what I have got from them. You can achieve Zero feedback to grid even with large load switching. Sunsynke, Inga and Deye have fixed this problem by doing the following. They have got a setting ( Zero Export Power) that will allow you set a watt value that allows the grid to give a small amount of power when you are using using pv power. This will raise the voltage a small amount good enough so that the switching off of large loads will not affect the feedback into prepaid meters. The bigger the load the higher the grid watts needs to be set to avoid feedback. Very, very nifty.

Cool, so the voltage is increased, but where does the power go?

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48 minutes ago, calypso said:

Cool, so the voltage is increased, but where does the power go?

It is measuring the total power from the grid that is supplying loads before and after the inverter and then sends back only enough to cancel this out by the limit you set. 

So if your zero export limit is set to 100w and the loads before the inverter is consuming 2kw, it will only send back 1.9kw back to supply these loads and reduce the grid usage to 100w.

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Hi

I should not call it voltage but potential difference. The current will flow from a high to a low potential. So by adjusting the "ac voltage" flowing  from the from the inverter, the current can flow either go to the  non essential load or to  the grid. If you have a higher potential (voltage) at the inverter side and a lower potential (voltage) at the grid side of the ct then you will feed watts back in the grid. If the potentials are swopped it will feed to the load. The ct accurately measures the current flow from or to the grid allowing the inverter to adjust the potential " voltage " to be set to the set (required amount). If you do not feed back to the grid and you have excess power after feeding essential, non essential loads and charging the batteries, the excess power would be lost. In this case you can  heat your geyser, start your pool pump ect. to avoid loosing excess power.

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 Hi DaveSA

The only way you will know what value to set to avoid the small amount of feedback when the load switches off as this is when the voltage will increase on the inverter side is to switch the 3.5kw load on and off and check the feedback and adjust value accordingly as the ismall ncrease in voltage will not be the same for everyone as this can be the result of resistance of the wiring which causes a volt drop caused by the distance to the load and wire thickness.when larger currents are drawn by the load.

 

 

 

Edited by Peter Topp
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  • 3 weeks later...
On 2020/10/05 at 1:07 PM, Fuenkli said:

i wonder what the real reason was why the CoCT has changed your existing prepaid meter 🙂. I am not aware of any one way prepaid meters who credit you (spinning backward) when you feed in.  

Be carefull of prepaid meters. Majority are counters. either direction affects the money on your meter. 99.9999% of meters will work fine but prepaid meters when you feed back into the grid sees it as you are using electricity. Thus you pay them max to feed back.

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Some actual information from feeding back into the grid and feasibility.  The Below is my usage.

I have 10 x 330W panels and a grid tied inverter.  I spend R 13 000 on the panels and a few R6500 on my  inverter. There where some issues on my billing side which have been resolved.  If some one is interested I have a Solis 3k3W for sale 5 months old dual MPPT for R 4500.  I used it for a test and it is replaced ( Hope I did not transgress)

If I add more panels I can turn the billing into 0 by end Dec. (This I am doing  due to the billing been resolved)



Facts are in COCT more than  600 Kwhr you pay R 2.51 ex VAT per Kwhr.  Now Eskom want a 10% increase and then the City wants an increase as well.  The chances are very good that soon you will pay R 3 Kwhr.  One problem comes in calculating the 600Kwhr they make use of a "floating" calculation. I have been billed R2.52 (EX VAT) per Kwhr @ 525 Kw.  Thus they can do what ever they feel doing and you can stand on your head they will stick to it.

If you spend say R30K on your solar a year or two and the escalations costs it will pay you.

With the "change" you are forcing two things.  1 Eskom and the others can steal less.  The City of Ape Town income will decrease then other levies will increase. Thus vote for another party not ANC or DA so there  can be an opposition so they can start spending less. Both these parties are hungry wolfs that are sucking us dry.

The fact is a 5 Kwhr inverter can take an average house hold account to zero sooner than you think.

What is very important is that no matter what you are decreasing your usage during the day and that is difficult to reflect. My daily isage now is +/- 13Kwhrs per day

Date Import Kwh Export Kwh Kw HrDiff Cost R Val
Aug 2019 552.760 15.20 537.56 R 1,005.6 R 1,005.56
Sep 2019 657.780 0.00 1195.34 R 1,239.4 R 2,244.98
Oct 2019 795.820 0.00 1991.16 R 1,564.0 R 3,808.93
Nov 2019 764.070 0.00 2755.23 R 1,489.3 R 5,298.24
Dec 2019 800.700 0.00 3555.93 R 1,575.4 R 6,873.67
Jan 2020 825.680 0.00 4381.61 R 1,634.2 R 8,507.82
Feb 2020 743.810 0.00 5125.42 R 1,441.7 R 9,949.50
March 2020 637.010 21.78 5740.65 R 1,190.6 R 11,140.09
April 2020 505.720 39.06 6207.31 R 1,075.0 R 12,215.06
May 2020 543.980 26.84 6724.45 R 980.9 R 13,195.95
June 2020 608.070 18.15 7314.37 R 1,109.3 R 14,305.21
Jul 2020 752.540 50.67 8016.24 R 1,425.1 R 15,730.30
Aug 2020 706.460 176.51 8546.19 R 1,224.6 R 16,954.89
Sep 2020 583.970 272.69 8857.47 R 874.4 R 17,829.27
Oct 2020 460.708 593.34 8724.84 R 412.8 R 18,242.09
Nov 2020 420.000 812.34 8332.50 R 177.6 R 18,419.72
Dec 2020 414.000 1257.00 7489.50 R-159.0 R 18,260.69
  10,773.078 3283.58 7489.50    

 

 

 

 


 

           
           
           
           
           
           
           
           
           
           
           
           
           
           
           
           
           
           
Edited by Erastus
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I want to add something more to the way COCT calculates costs. Your first goal would be to keep your account below 600W pM
The import and export values is directly from the COCT SAP via csv down load.
Look at the difference between Aug & Sept when the export started to work well. The feedback difference is 100Kwhr for the month. The effect on the account is +/- R400pm x 1.15 = R460 that you can use to pay your solar.

The same system fully kicked in in Oct and now the saving is +/- R 950 per month.  That pays your solar and it should last 20 years.

 

Jul 2020 752.540 50.67 8016.24 R 1,425.1 R 15,730.30
Aug 2020 706.460 176.51 8546.19 R 1,224.6 R 16,954.89
Sep 2020 583.970 272.69 8857.47 R 874.4 R 17,829.27
Oct 2020 460.708 593.34 8724.84 R 412.8 R 18,242.09
Nov 2020 420.000 812.34 8332.50 R 177.6 R 18,419.72
Dec 2020 414.000 1257.00 7489.50 R-159.0 R 18,260.69
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This brings me to my last bit of splatter.  Batteries or no batteries.  3 x 48V x 100 systems costs +/- R 36 000.

Should one chose to add batteries to your system compare the two tables below.  The same system only addition of 7200 Kw batteries.
This creates an immediate difference of R 803 per month.  Roughly 40 months or 4 years the batteries are paid and you are not affected by Eksdom neither the theft of the politicians.

Battery life is expect to be 10 years a saving of R12000 per year or R72 000 minimum over 10 years.

These values are not thumb suck it is from COCT SAP and directly from my account. I have added the exl file for those who are interested in it.




image.thumb.png.16823f10da99ccf0d9dc988ed26a14f6.png

Oct.xls

Edited by Erastus
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  • 3 weeks later...
On 2020/10/05 at 3:57 PM, Bobster said:

My gut feeling is that municipalities for some reason don't want to encourage solar, or at least systems that feed back into the grid.

It's not a secret. Most municipalities make a large portion of their revenue through electricity resales. From what I can find online, Eskom sells electricity to direct customers at around R1.16/kWh. The municipalities probably get it for less. The municipalities mark it up to R2.00+/kWh with their fees, tariffs, IBT scales and other NERSA approved BS. Other than some minor distribution costs it's like printing money.

Check this out from the Tshwane Draft Bylaws for Embedded Generation:

6.10 Risks
6.10.1 Economic
Increases in the price of electricity and the rapidly decreasing costs of EG solutions will impact negatively on municipal revenue. In future this may lead to grid defection, with serious revenue consequences. It is therefore important that the City creates an EG connection environment that is customer-friendly.

And:

6.11.1 Revenue
There could be a revenue dip due to the introduction of EG, in particular in the residential sector, and this should be rectified by appropriate tariffs. Tariffs need to be adapted due to EG being part of the energy mix.

http://www.tshwane.gov.za/sites/business/Bylaws/Draft%20ByLaws/28.%20Proposed%20Embedded%20Generation%20Policy%20to%20support%20and%20formalise%20procedure.pdf&ved=2ahUKEwil4PudoIXtAhVipHEKHVb9CG8QFjABegQIBBAB&usg=AOvVaw1cks5-EcFHKgeY7OFNVhpD

The thought process and reasons are blatantly clear.

Edited by Surge
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11 hours ago, Surge said:
On 2020/10/05 at 3:57 PM, Bobster said:

My gut feeling is that municipalities for some reason don't want to encourage solar, or at least systems that feed back into the grid.

It's not a secret. Most municipalities make a large portion of their revenue through electricity resales. From what I can find online, Eskom sells electricity to direct customers at around R1.16/kWh. The municipalities probably get it for less. The municipalities mark it up to R2.00+/kWh with their fees, tariffs, IBT scales and other NERSA approved BS. Other than some minor distribution costs it's like printing money.

Yes. A couple of posts later I made the point that municipalities see electricity as a revenue generator. I don't mind too much because the City has to provide lots of services and it costs money to do that. I almost feel a little guilty lately because City Power still have the cost of providing a connection to my house and I expect that connection to be reliable and safe and etc but they get maybe R90 from me a month. I almost don't blame them for their repeated attempts to add a flat fee to the bill for pre-paid users.

We may also be getting cheap juice in Johannesburg. I'm still on the pre-paid tariff (which even with the gerrymandering of tariffs of the last few years is still a money saver for most residential customers) and I am paying R1.72 per kw/h for units that I purchase up front. 

Yeah, I know. Eskom is a cesspit of malfeasance and City Power is crippled by years of neglect and not updating infrastructure. These are serious problems, but I don't disagree with the principle of the municipality charging me more than Eskom charges them, nor with them effectively robbing Peter (folks like me with income and who can pay) to feed Paul (unfortunate souls below the poverty line who get free, limited electricity and water). And they can't impose any old increases they like - Eskom have repeatedly been smacked down the last few years and got less than they asked for.

I like the cut of the current Eskom management's jib (or at least dislike it less), but they have inherited a problem that somebody else made and the only way they can repair the situation is with tariff increases. So that's a further driver for making your own, but every time somebody does that it's also a loss of revenue to them and to the municipality. So it's a non-virtuous circle.

Edited by Bobster
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On 2020/10/06 at 9:19 AM, Bobster said:

Well I'm no electrical engineer, just a common or garden computer programmer *, so I figure there is some reason that I don't understand and that an electrical engineer might. I think I've seen on this forum that in CT there is some factor that is applied as a limit to what you can install, and I've read several times that in some parts of Australia they have problems because they can have too much power on the grid (or a local segment thereof) during the day and then suddenly they have a large nett load as the sun starts going down.

Maybe it's just as simple as electricity being a revenue generator (pardon the pun) and so whilst they can't stop you having solar they can make it expensive for you to be in a position where they start paying you rather than the other way around.



* And I know my place. I used to work for a big healthcare group and in the IT department we used to have a little joke: 
Q: What's the difference between a neuro surgeon and a computer progammer?
A: The programmer knows he doesn't know anything about brain surgery.

Very simple to control.  You convert Koeberg Nuclear Power Station from a base station to a load following station. Eskom suppose to have spinning reserve. That is where the pawpaw hit the fan. The spinning reserve by non engineers was a so called waste. The growth plan was filed in file thirteen the new MD was paid a huge amount for the savings and today there is load shedding.

With SA being so wide there are "3 time zones" in a day. Thus the east can support the West in the morning and the West the East at night.  If the planner understands numbers and the usage patterns it can be easily managed.  THe number understanding is the issue.
If you have 300Mw in the east then have 300Mw in the center and 300 Mw in the West. Business have a good 1.2G whatt extra and at night you can replace the 300MW station with one power station. When the West lost its sun the east peak is almost gone  ...

It is very simple IF YOU UNDERSTAND the numbers.

The new plan is only to create business for friends and not so much looking at the need and what to do where ever....

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