Micro inverter to grid

Not to mention back feeding through a plug is seriously dangerous.
 
I have covered the legality previously here -

http://mybroadband.co.za/vb/showthr...ons-in-CPT?p=15145318&viewfull=1#post15145318

As well as a bazillion other times on the various Solar threads.

To be honest, I'd love it if Cape Town was Solar friendly. It is the complete opposite though, so its either off-grid (which is what I did), go illegally (which is what most do), or do the SSEG stuff and pay through the nose (only a handful in Cape Town, and it really only benefits businesses with >10k a month spend).

But hey, what do I know ;)
 
Hi Isheed_cn,

The device is not technically connected to feedback into the grid, you are simply reducing the amount of electricity drawn from Eskom.
The reason they do not want you to feedback is that it destroys their business model, as you would be "receiving" the retail price for electricity and not the wholesale price that they pay.

So you would be getting R 1.83 for each unit, when the City pays R 0.30 (for example) for the unit and marks it up to cover their expenses.

It's like you making a iPhone at home for R 300.00 and returning it to Apple for R 8,000.00, not a viable deal for Apple.

If you read the documentation, the Cape Town City is happy for you to be a net-consumer, but not a net-producer.
They are even happy if your consumption is zero. They do not really want to be involved in monetizing your returned power, and we all understand why, it's unfair on the producer.

And you are allowed to connect a device as long as it does not feedback into the grid, if your base load is more than 300W, you will never feedback into the grid and therefore not need the certificate as you are not in violation of the law.

If your base load is less than 300W, you probably don't need a solar solution as the amortization time is too long to justify the expense.

How do you know what your load is? It's quite easy to measure, go get a power meter and clip it to your DB supply line and have a look.

(PLEASE BE VERY CAREFUL, AS VOLTAGES IN THE DB CAN KILL YOU IF YOU TOUCH EXPOSED WIRES OR TERMINALS, BUT IF YOU ARE SENSIBLE AND CAREFUL NOT TO TOUCH ANY EXPOSED TERMINALS OR WIRE ENDS THERE IS NO MYSTICAL FORCE THAT WILL JUMP OUT AND KILL YOU)

Ellies sell one, http://www.ellies.co.za/energy_monitoring/efergy/Wireless-Energy-Monitor/FSEM2, this is the one I use.

I have connected many of these meters to various DB's and I am still alive to write this, it just takes common sense and care.

I don't think people should be kept in the dark (pun intended) when there is perfectly simple solution to reduce your dependence on the state and move to a more self sustainable position.

Kind Regards
Peter
Evolt Energy
 
Hi Isheed_cn,

I agree, if you have R 200k to go off grid go for it, for the average person that would be, at a savings rate of R1000.00 a month, an amortization time of about 200 months, or 16 years. Leaving you with outdated panels, multiple replacement batteries and old technology.

With a micro inverter, your system is DIY, (if you can wire a plug you can install it), you can expand it at will and take it with you when you move. At low watts it is cheaper than a string inverter installation.

See these links for details:
1. http://www.australianmicroinverters...s-micro-inverters-vs-string-inverters-winner/
2. http://www.businessspectator.com.au...ar-energy/has-micro-inverter-revolution-begun

The only issue is that there is no generic way to prevent feedback to the grid, well not yet, not that I know of. So you need to know your base load and size your power production appropriately.

Kind regards
Peter.
Evolt Energy.
 
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Hi Sinbad,

Let me correct you on both points:

1. Could you please explain how, with anti-islanding there is "Exposed 220v on the male plug."?

The function of anti-islanding is to shut down the output in the event of losing grid power.
The instant you unplug the Renesola micro inverter from the wall socket it shuts down.
It will only restart once it has detected that it is plugged into the grid again.
It uses 3 independent mechanisms from frequency shift to voltage differential to do this, it has to, its an interational law.

2. How is plugging the device into a wall plug, which is earth protected, "Bypassing of earth leakage."?

The earth is wired all the way to the micro inverter, including its frame and additionally strapped to the solar panel frame.
This gives you an unbroken earth from plug to micro to panel, ground faults will trip the DB earth leakage immediately.

Kind regards
Peter.
Evolt Energy.
 
@Evolt-Technical.

Regardless of what you've written or think, City of Cape Town considers any generating equipment that is connected to the grid to require a SSEG licence, regardless of size. This includes dinky little 300W generation, which really makes the use of that in Cape Town pretty moot, as its just not feasible to get something that small licenced.

If you think that you are somehow exempt from that rule, I suggest you speak to either Ryno van der Riet or Brian Jones (head of Green Energy at City of Cape Town) at the CoCT electrical department, and have a chat with them to disabuse you of that notion.

I'll make it easy for you:

Brian or Ryno can be gotten at Electrical Services on 021 446 2015 or reach them via email at
[email protected]
[email protected]

Or go visit them

7th floor ENS House
No 2 Lower Loop Street
City of Cape Town 8001


As for supplying power through to a plug, that is completely illegal also, especially as far as the electrical standards are concerned!
All wiring must be wired into a DB, and supplied with an dedicated switch to turn it off.
Suggest you read this great article, which covers the requirements in sufficient detail - http://www.ee.co.za/article/connecting-pv-system-grid-earth.html

The other little wrinkle is that your equipment also doesn't appear to carry type certification ( NRS-097-2-1 ) to be usable in South Africa, or at least I couldn't find it listed as having that. Thats not a huge issue, it just needs to be tested and paid for (roughly 30k-50k depending on test house and who does it for you). Until thats done though, its... illegal to connect to the grid.

I am not anti-solar. I have my own solar installs (albeit off-grid as the fee's don't make it worthwhile to be on-grid in Cape Town).
You are however, telling people untruths, and promoting dangerous and illegal practices.

I cover the legalities on my blog here - http://goingsolar.co.za/solar-grid-tie-legalities-in-cape-town-south-africa/


The only issue is that there is no generic way to prevent feedback to the grid, well not yet, not that I know of. So you need to know your base load and size your power production appropriately.
Click to expand...

Perhaps something like... this? http://www.sustainable.co.za/microcare-grid-tie-limiter.html
or this http://www.exsolar.co.za/products/grid-tie-limiter/

L.
 
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Hi Isheed_cn,

Thank you for your comment, let me respond to your two main points.

My interpretation of the law, is just that, an interpretation, I have never stated that the system was legally allowed to be installed, I have just asked everyone in this discussion why they think it is illegal. It is the absence of breaking a law that makes an action legal.

I am not a lawyer, my skills are in other areas, my motivation is to try and help people, help themselves, save money.

I would rather people spend R7,500.00 on a small solar system that helps them save money, everyday, and pays for itself in 5 years, than have them do nothing, as a "fully off grid system" is beyond the reach of most people.

Your two points are:

1. "completely illegal" (according to the referred document)
2. "illegal to connect to the grid" (requires a NRS-097-2-1 certificate)

1. I have read the referred document, and will post a point for point on it on our web site, it's a bit long for this forum. (once I have completed my response, I will edit this article and replace this text with a link)

2. I do not import the Renesola Micro Inverter, I have just put up a suggested system that uses the product, the Solar Saver 300, which shows you the components required to connect it up and have it help you save money.

If it now turns out to be illegal to connect to the Cape Town electricity grid, then I will do my best to arrange with the manufacturer to follow the necessary testing procedures to have their device certified.

As to your suggested grid-tie limiters, both, unfortunately only work with specific manufacturers string GTIs (grid tie inverter).
The Microcare with Microcare and the Exsolar with Fronius. (to the best of my knowledge).
Which puts the system at a starting point of about 30k+ (5 panels to get to 150V minimum, and a 1.5KVA inverter).

I will contact Renesola, Brian and Ryno and see what is required regarding the NRS-097-2-1 and the City of Cape Town's other GTI requirements.

Kind Regards
Peter.
Evolt Energy.
 
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1) I point out where you completely disregard the safety rules laid out by Eskom which are mandatory.
Its not a discussion or I believe in my view that xx, its quite clearly not to wiring code.

It will not pass an electrical inspection. If you have an electrician that believes it does, then I suggest they take a careful read of the literature regarding this, and revise their views. SANS requirements are listed in the link I gave you earlier.

Documents to read are listed below. I have these on my website, or a google search can find them.

NRS 097-2-1 Grid interconnection of embedded generation Part 2: Small scale embedded
generation, Section 1: Utility interface.

http://www.goingsolar.co.za/uploads/NRS 097-2-1.pdf

Specifically - 4.2.4.1, 4.2.5, 4.5
Annex B is also a good read.


SANS 10142-1 The wiring of premises;
http://www.goingsolar.co.za/uploads/SANS10142-1Amdt8.pdf

(there is a 9th amendment, I don't have it to hand)

The South African Grid Code (google for it).


2) It doesn't matter if you import it or not. In order to connect to the grid it requires certification.


As I quite suspected initially, the legal implications make using a micro inverter a non viable product for our environment, at least in Cape Town, as I stated Cape Town requires an SSEG if you export power.
If you have no way to limit the power exported, then you have to sign up for the grid export SSEG and pay a daily fee of R14 (current rates)
This makes using a single micro inverter a non starter.

Given 5 hours of generation on a 300W micro inverter, you'll get about 1KW out at best, or generate a savings of R1.86 or so.
You'll literally be losing money if you install one legally.

Conversely, if you need to install 20 or so micro inverters + panels to break even, then its pointless going the micro inverter route, as its cheaper and better to go with a central inverter..

Again, other municipalities have different requirements, and it may be usable with their legislated setup.


While your aims are laudable, the legality of it currently is that it is illegal to connect and use without the appropriate certifications, wiring compliance, and municipal requirements.

On the face of it, Cape Town appears to be pro-solar until you look at the legislation, and realise they are firmly into protecting their income via 'taxation' on electricity.

The good news though, is that getting off grid is getting cheaper by the year, and is getting more and more viable as the retail pricing per kw goes up. The bad news is that the people that Cape Town can least afford to lose going off the grid, are the ones that are leaving.
At the end of the day, this will lead to rates hikes, and/or an eventual acknowledgement that the current status quo is not viable, and the poor will have to pay for things, just like the rest of us, instead of being subsidised by us.
 
Hi lsheed_cn (i changed to an l),

If you don't mind, since you seem to have done a lot of research on this subject, would you like to help me get to the same point as you.
I believe in Micro Inverter technology as a simple solution to a lot of people's problems with electricity increases.
I would like to see if, working together, we could overcome these hurdles and get to a point where micro inverters were "legal".

From our discussion so far I have identified 3 reasons that you feel that the city has declared them "illegal".
I will order them from easiest to more difficult to fix.

1. Wiring not conforming to standard
2. Missing NRS 097-2-1 certification
3. Grid feedback prevention and SSEG.

Could we tackle point 1 first please, ignoring the rest for now.

From what I understand is that embedded generators need the following:
1. Anti-islanding
2. An AC isolation switch
3. A 2 pole 10A breaker
4. An uninterrupted earth from house to panel
5. The cable connecting the devices to each other need to be a specific cable class with two core and earth.

Have I left anything out, or are there other requirements that I have overlooked?

Thank you
Peter.
Evolt Energy.
 
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I have:

2 x 300 watt photo-voltaic panels
1 x 2400 watt pure sine-wave inverter with an MPPT solar charger
4 x 105 a/h batteries, connected two in series
4 pole isolator for the house (3 phase + inverter)
Earth leakage for the inverter output
20 amp double-pole cb for the mains supply to the inverter
40 amp fuse on the +ve feed from the PV panels
60 amp double-pole cb for the battery to inverter feed
Cable from the PV panels is 4mm UV proof cable

With this setup, I feed all the lights in the house and 5 plug circuits

The inverter has been programmed for "Solar first" to feed the plug circuits and charge the batteries. You use a USB link from a Windows computer with the program "Watchpower"

From about 07h00 to 19h30 in summer, the inverter supplies all the current to the house. The load varies between 4% and 20%
From about 19h30 to 07h00, it switches back to "bypass mode" allowing the incoming mains to feed these plugs and lights
This is controlled automatically. I set the battery charge current to 20 amps, maximum 26.8 volts (it is a 24 volt system)

I have figured that I need another 2, 300 watt panels and probably another 4 batteries so the PV panels can recharge the batteries if I switch off the incoming mains supply

To test this, I installed a system with 4 PV panels and 8 batteries and this works as enviaged

If it is a cloudy day, the PV panels cannot supply sufficient current

The Inverter is a MPP Solar device and came from Taiwan at about R5000 in May. The batteries are R1600 each (Communica) and the PV panels and hardware about R5000

I am not interested in feeding back power into the grid yet, just being reasonably self-sufficient. I am saving about R30 a day in electricity cost

There is also a solar water heater which does away with any electrically heated water. In winter, there is a heat-pump with a 1.1kw motor. This comes on from 12h00 to 18h00

My monthly electric cost is about R550

There is a lot of useful info on YouTube from Australian users about MPPT chargers
 
Hi chrisc4290,

That's a very clever idea, split off some of your circuits and have the inverter bridge them.
Since your inverter is not capable of supplying the "heavy duty" electrical appliances, you don't bother supplying electricity to them.

I think they call this a hybrid-inverter, being 3 devices rolled into one, an MPPT charge controller (DC), a battery charger (AC) and an inverter (AC)?

If I remember correctly, you can run it without batteries?

I assume that you don't mention the make and model as it's not on Isheed_cn's list of approved devices, or you are not in Cape Town :)

Kind Regards
Peter.
Evolt Energy.
 
I assume that you don't mention the make and model as it's not on Isheed_cn's list of approved devices, or you are not in Cape Town
Click to expand...

First off; This is an i. This is an l. Spot the difference? :D

Secondly; My list of approved devices? :wtf: Don't you mean the municipalities or Eskoms?

I merely pointed out that legality of it currently is that it is illegal to connect and use without the appropriate certifications, wiring compliance, and municipal requirements. I also pointed out that having to follow that for micro inverters makes them unfeasible to use in Cape Town, as the costs are then prohibitive.

If they catch you, they will try to fine you. That said, trying to catch someone with a microinverter or two feeding back into the grid is going to be difficult, although not impossible with a spot of data analysis.

Thats a risk you can take though as a consumer. Illegal wiring doesn't seem to stop the rest of the populace.
The middle class however are an easier target when it comes to being fined and being compliant.
As an installer it might be a different matter, as the authorities may be interested in a heavier fine when it comes to that sort of thing.

Another issue is that feeding back into the grid with a pre-paid meter / smart meter is also going to trip the meter anti-tampering. Even if you are only feeding back say 300W peak, its quite possible that the house base load will be under that 300W during the day. At that point in time, you will be feeding back to Eskom side, and the meter will trip, and the municipality will find out about your little install.
If you are on an older meter, this is not an issue.

As micro inverters are grid tied, and you say that they cannot be limited (although a cursory check of the manual suggest that frequency modulation would work as they do have anti-islanding), this kind of makes them unfit for use on smart meter installs. This is also a reason that the muni's are highly invested now in installing smart metering, as it scuppers a lot of smaller solar installs in the bud, thus ensuring profits..


I have no ball in this game, my installs were done by me, for me, and I imported most of the equipment I use myself, *and* I made sure that the equipment I use carries the relevant NRS certifications, is wired up according to standard, etc etc. I decided not to go SSEG, and instead went completely off-grid, mostly due to the lack of benefit to being SSEG. I'm quite happy about that choice, and would (and indeed have) done it again elsewhere.


From what I understand is that embedded generators need the following:
1. Anti-islanding
2. An AC isolation switch
3. A 2 pole 10A breaker
4. An uninterrupted earth from house to panel
5. The cable connecting the devices to each other need to be a specific cable class with two core and earth.
Click to expand...

You seem to be getting closer toward something that conforms to the electrical code on some of the requirements.
I see earthing/grounding finally being mentioned, and breakers mentioned. I am not an electrician or an engineer though, and speaking to a qualified one would be in order. Not someone with just a wiremans licence, a proper fully qualified one.
Speaking to Brian or Ryno for exact requirements would be recommended.


Again, Cape Town is vehemently anti-solar, so the rules are onerous, and the pricing discouraging, so even becoming legal for a grid tied micro inverter setup makes it a non-starter.
 
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Good news, please see the response from ReneSola, looks like they will be certifying the Renesola Micro Replus in South Africa as part of their global certification efforts.

Hi Peter,

For the micro-inverter, no customer asked the NRS certificates until this moment. We will start to evaluate NRS certificates and talk with our supplier about the plan. Since we are busy with the certificates for EU and USA at this moment. Hopefully 3-6 month, we will get NRS for SA.

Best regards.
Clark Ping
Email: [email protected]
ReneSola South Africa (Pty) Ltd.
Click to expand...

So that is 2 of the 3 objections we have identified, solved.

The required documents are available at : http://www.capetown.gov.za/en/electricity/Pages/ServiceApplicationForms.aspx

You will need to fill in submit (I am assuming, as I have not yet done it):
http://www.capetown.gov.za/en/elect...ion of embedded generation (5 June 2015) .pdf

The document we are interested in is: http://www.capetown.gov.za/en/elect...esforEmbeddedGeneration 6 July-2015 Final.pdf

1.3. Metering and Tariffs
Residential consumers may adopt one of two approaches to connecting SSEG to the grid:

i. Consumers wanting to connect SSEG to the grid without being compensated for
reverse power flow will be required to install reverse power flow blocking protection to
prevent reverse power flow onto the electricity grid. The consumers may then, subject
to the ruling policies for tariffs and metering, keep their existing meter and remain on
the relevant electricity consumption tariff. In other words, for this option the
conventional credit or prepayment meter is NOT allowed to run backwards.

ii. Residential consumers installing SSEG who wish to participate in the SSEG tariff must
have a bi-directional AMI credit meter installed....
Click to expand...

You still need to fill in the SSEG registration form, but can state that you have no intention of feeding back to the grid.
The requirement defines a net-producer as someone, who during the course of a year, ends up producing more than they consumed.
There is almost no-way a 300 micro inverter will be able to produce enough electricity to result in a net-producer situation.
Strictly speaking you need a device that prevents the meter from running backward, but no such device exists for micro inverters so there is no way they can insist you install a device that does not exist :)

I will email the city and see if they can clarify the micro inverter situation, and exactly what the requirement for a device that prevents feedback to the grid.

I have quite a good understanding of what is required to make such a device, so if this is something that is required, I am pretty sure we can make one.

Kind regards
Peter.
Evolt Energy.
 
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There is nothing there that I haven't told you already (sometimes repeatedly) within this thread, including the SSEG tariff options.

Strictly speaking you need a device that prevents the meter from running backward, but no such device exists for micro inverters so there is no way they can insist you install a device that does not exist
Click to expand...

I guess you've never dealt with government regulation before. If something does not exist, then they don't laugh and tell you haha, no you don't need to comply, they laugh and tell you haha, no, you can't use your device.

Secondly, I suggest you lookup AC coupling. The micro inverters can be controlled with frequency modulation, which again strangely enough, I have already mentioned. Renesola pdf docs explicitly mention the key ingredients for that - "over / under voltage, over / under frequency, reconnection time".

If you use Enphase you can also use their proprietary powerline control over modbus, its possible that Renesola has something similar, as their docs briefly mention Power Line Communication.
I'm having a bad internet day here in China, so I can't check as well as I'd like on that.

So that is 2 of the 3 objections we have identified, solved.
Click to expand...

Uh, no. Thats 1 ok, you're right, we do need an equipment licence, and we have some wavy hand stuff about the provider saying we're thinking about doing it in the future.

The other "objection" I had was that you could just maybe try to possibly comply with the electrical code, as its actually there for our benefit.
Its only after a number of people, including myself pointed this out that you hand wave over that also and say, ok solved.

And the last objection was again regulatory, which you now appear to concur with.

None of which are solved, just that you now agree that I happen to be correct.

Are you going to go back to previous customers now, and remedy a deficient install on your own dime?
Or are you going to leave them with an out of code, possibly electrical hazard thats also illegal to use and install?

To clarify, in an overly harsh manner:

1) Its still illegal to use. No, this is not an opinion, it is a cold hard fact, due to a number of issues, some of which are listed below.
2) You currently have no equipment licence (NRS 97-02-1) for the product. See #1
3) You recommend installs that fail the electrical code in a number of ways. (Grid code, SANS Embedded Producer code etc), again See #1
4) Your installs don't comply with council regulations. See #1
5) Even if it did all comply, the council regulations for Cape Town make it likely unfeasible cost wise to use.

Micro inverters are a nice solution, but not for our regulatory environment, and definitely not in Cape Town.
Grid tied is not the way to go here, Hybrid or Off Grid makes far more sense (and cents!).

Good luck, but I'd suggest a different solution for your clients that isn't going to get them or you into trouble now, or in the future.
Longer term I don't see this changing, as either Eskom gets worse (in which case Grid Tied is a bad idea), or the anti-solar regulations get worse to prevent more solar users on an ever decreasingly used grid, as people migrate to offgrid as prices are too high.
 
Fortunately I have installed all the systems myself, and have improved/corrected the wiring as our discussion progressed.

I will have all the ads changed to state the following:
Requirements for installation in South Africa:
1. The micro-inverter is not yet NRS certified, and therefore illegal to connect in Cape Town.(certification is pending)
2. Specific electrical wiring rules need to be followed when connecting the micro-inverter to the grid. (Grid code, SANS Embedded Producer code etc)
Additional Cape Town specific requirements:
1. The SSEG form must be completed, submitted and approved before purchasing the device.
2. If your intention is to consume all you produce, a grid-feedback-prevention device must be installed, to comply with legislation.

(edited)
Click to expand...

Regarding frequency-shift, you are correct, and the ReneSola micro inverters do have frequency-shift power control. The problem is that you need to have a micro-grid (your own grid, disconnected from Eskom) in order to do this. There is no way that you will be able to frequency-shift the Eskom grid.

I have emailed ReneSola technical regarding their own powerline control protocol, hopefully there is some way of using it to prevent feedback to the grid.

I have also emailed the contacts you suggested at City Power, and will post their response. I think this is a fight worth fighting and I am not one to simply give-up, yet.

If you read the following article, you can see how, working with micro-inverter-enabled homes, Hawaii is able to stabilize their grid:
http://www.greentechmedia.com/articles/read/enphase-to-help-hawaii-ride-its-solar-energy-wave

It's a pity that Eskom and City Power are not thinking of how they can "use" our home generating capacity to help the country grow.
Instead we are looking at spending billions on a nuke.

Kind regards
Peter.
Evolt Energy.
Simple solar saving solutions.
 
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Without NRS certification, its illegal to connect up *anywhere* in South Africa to an Eskom or Municipal fed grid.
Not just Cape Town.

Cape Town has additional requirements over and above Eskom's as mentioned.
Other municipalities are easier to deal with, and / or have differing requirements.

Honestly though, its not about stabilizing a grid, its about actively discouraging things that potentially reduce their revenue income from electrical sales, which is why I said they're vehemently anti-solar, more-so if you look at their policies/pricing..

The problem is that you need to have a micro-grid (your own grid, disconnected from Eskom) in order to do this. There is no way that you will be able to frequency-shift the Eskom grid.
Click to expand...

You don't frequency shift Eskom grid, you shift the micro inverter side.
eg

Inverter <-> DB <-> Grid Tie Feedback Limiter -> Grid
 
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Hi lsheed_cn,

I have made changes to my disclaimer as per your suggestions.

I think you are wrong regarding frequency shift controlled micro inverter power control.
The sites I have found all mention a micro-grid, could you post a link to an example where they do not use a micro-grid for frequency control.

http://www.exsolar.co.za/blog/energy-metering/frequency-control-of-microgrid-tie-inverters/
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&tp=&arnumber=6878637

Thank you
Peter
Evolt Energy.
 
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