I reside on a smallholding with a 3-phase 100Kva Eskom Supply on their Landrate 3 tariff - Fixed costs are about R4,000+Vat per month + R1.78 per kWh for consumption. Total account about R10k per month.

There are three houses of which two are rented out and we installed Pre-paid submeters in them.

The main house (mine) has a 9.7 kW ground mounted Canadian Solar array facing North with seasonal adjustment and connected to a Diehl - Platinum 16kw 3-phase Grid Tied Inverter plus a Sunsynk 8Kw with 12 x 450watt Canadians on the Garage roof facing East (N-E) and West (N-W)@ 45 degrees.  Storage is 5 x 4.8Kw Hubble batteries on the one phase supplying my essential loads (basically all plugs & lights)

The first option is if we stay on the same tariff structure but downgrade the supply to 50kVa. The fixed monthly fees decrease by about R1,000 per month BUT now they want to replace my old type meters at a cost of R1,800 odd plus an additional R9k deposit. 

The alternative is to go full-out for 50kVA connection on Ruraflex Gen  - with a TOU structure and bi-directional meters. The cost for this.....wait for it....R17k for the meters and R44k in extra deposit. Besides the prohibitive costs I am not particularly excited about the approval process - for which I haven't been able to find any info.

I am now leaning towards the first option but am worried how the new meters would treat my occasional feed-back. The two rental houses  probably absorb the majority of the excess generated by the Grid Tied system but there will be feed-back at times.

Does anybody know how the new Eskom Post paid electronic meters will handle my use ?

Any advice or suggestions would be highly appreciated.

Thanks for your reply@87 Dream  and I agree with your logic.

Just wished they made it easier - cost wise - to normalize (read legalize) a feed in connection.

I might need my head read, but somewhere deep inside, I would like to comply.

Any other suggestions or comments welcome guys.

To the best of my knowledge, there are only draft papers prepared, and that was a few years ago. They do have a feed in tariff published 👍 11 cents/kWh…. Apart from that, you will not find anything me thinks. Its a revenue protection thing for them. So nothing to work from that I could find.

43 minutes ago, Sarel said:

To the best of my knowledge, there are only draft papers prepared, and that was a few years ago. They do have a feed in tariff published 👍 11 cents/kWh…. Apart from that, you will not find anything me thinks. Its a revenue protection thing for them. So nothing to work from that I could find.

As far as I could establish these is no feed in tariff - on Ruraflex Gen anycase - only essentially a  give - and - take arrangement. They measure feed in for every TOU slot ( Peak / Standard / Off peak). You can then utilise the feed in credits - In the same TOU slot - cost free within a determined timeframe, which I think is their financial year. After which it expires.

43 minutes ago, 87 Dream said:

Wow, I feel for you Brickman. Unfortunately the equation is only in one direction & that is not in our favour. 

You are paying a considerable amount of money for electricity. What may work in your favour is to take that plunge & spend your money on your own honest system. Go off the grid! It makes sense & the economics are in your favour. Let's face it, 24 months later we will still be having this conversation & all that would have changed is that you will have a bigger hole in your pocket & none the wiser. In 24 months you will have sponsored R240k even more to the state. 

This can get you independent. The money is in the storage of energy. Yes it will be a massive capital out lay. In 24 months you will be the owner of that system. Off gridding involves a bank of batteries at least 4 X your daily consumption.

Many clients come to me & at this spend rate you are in the business study of off-gridding. The storage capacity is made even cheaper if you are willing the stack your energy & sea freight from China. All I am saying is you are a man of integrity & I respect that. Just hate when a worthy good citizen is being squeezed by the state.

Of course without getting into anyone's business here but this takes a huge financial commitment. But me thinks you cannot be paying so much for electricity & in 24months I can guarantee you only one thing if you stay on Eskoms Grid. Your tariff will have increased & loadshedding will still be happening.

87

 

 

 

Agreed it only works one way - and my good nature only goes só far🙃

Going Off grid is a bit scary with the two tenanted houses. Although essentially, being pre paid submetered, the are buying from me - which only helps.

Getting our water heating Off grid has always been my next step.

I have been toying with the idea of large volume hot water storage for DHW (1,000 to 1,500 litres) to provide for a few days of autonomy.  Solar thermal drainback system with  a non pressurised vessel and corrugated stainless steel tube heat exchanger.

Maybe start there and see where it goes ?

21 hours ago, 87 Dream said:

Wow u need to do a calculation. If you have the old spinning meter I would feed not just blips, I would feed back as much as possible to get that unit to spin backwards. 

 

This sounds like a risky tactic to me. I've heard about meters doing this, but how is a computerised billing system going to deal with this?
Last month closing = 123456

This month closing = 123111

Oh wow! The meter must have gone all the way around, zeroed and then gone forward again. The system will not stop to consider how you might have used so much juice in the space of a calendar month.

If the feedback amount is small then you might get away with it (EG would be 123489 instead of 123567), but eventually you will end up in the situation I describe. 

On 2021/10/26 at 3:23 PM, Bobster said:

This sounds like a risky tactic to me. I've heard about meters doing this, but how is a computerised billing system going to deal with this?
Last month closing = 123456

This month closing = 123111

Oh wow! The meter must have gone all the way around, zeroed and then gone forward again. The system will not stop to consider how you might have used so much juice in the space of a calendar month.

If the feedback amount is small then you might get away with it (EG would be 123489 instead of 123567), but eventually you will end up in the situation I describe. 

We have two other residences on the same property which should absorb most of what I generate - Which is roughly 50 to 60kWh per day on the 3 phase Grid Tie from +- 9,66KwP of panels. They are in two strings - 14 x 335w (CS6U) and 14 x 355w (CS3U) Canadian Solars - on the Grid Tie's single MPPT. Plus another 20 to 25 Kwh per day on the 8 kw Sunsynk which has 12 x 450w (CS3W) Half Cell Canadian Solar panels (6 East + 6 West).

Unfortunately our main Eskom connection is about 100metres from my house which makes it a little challenging to communicate the amount we feed back into the Grid. Even if i did , I am not sure if the Diehl Grid Tie has the capability to Zero the back feed.

56 minutes ago, 87 Dream said:

As stated before Brickman, you are in Off grid study territory. I know you mentioned you have a 8kW SunSynk, the 12kW 3 phase would have been a welcome alternative I think. Because on the Voltronics side I have worked with the 15kW Infinisolar on a similar project & it removes the challenge of single phase Vs 3phase. My head hurts when you tell me you are sponsoring Eskom with R10K pm. 

87

Care to explain a little what you mean by " removes the challenge of single vs 3 phase.."

Further following  my "Off Grid Study" as you put it  ... another hurdle to overcome with my current setup is that 75% of my generation is by 3 phase Grid Tied Inverter which becomes Zero during Load shedding. 

49 minutes ago, Brickman said:

another hurdle to overcome with my current setup is that 75% of my generation is by 3 phase Grid Tied Inverter which becomes Zero during Load shedding

Micro grid, that serves to solve that specific problem. I shared a post on here called Micro grid, explains it there. Also my Micro grid system is fully documented and explained on here.

@SarelI have been following your Micro Grid journey, which I have to say has impressed me to no end.

The fact is that I am not designing from scratch and would like to use as much of the existing equipment as possible.

Sure, that is not ideal and may require some alternative thinking.

At least I have a new Victron 250/100 Smartsolar MPPT to use in the planning😄

 

Maybe investigate if you can have 3 Sunsync's and add the Diehl on their output and create a Micro grid that way? If that's not feasible, look at Victron or Sunnyboy or ABB or Schneiders. Zero feed in may be n issue tho....

28 minutes ago, Sarel said:

Maybe investigate if you can have 3 Sunsync's and add the Diehl on their output and create a Micro grid that way? If that's not feasible, look at Victron or Sunnyboy or ABB or Schneiders. Zero feed in may be n issue tho....

If I go for 3 Sunsynks,  an option would be to just rewire the panels for the Sunsynks lower MPPT voltage and leave out the Diehl . Will then already have 8kw per phase = 24 kw equivalent of a single phase setup

With the Diehl you will have better efficiency likely, but it's just another option. Many ways indeed....

1 hour ago, 87 Dream said:

Exactly what others are saying. Your system would work better on a 3 phase Sunsynk. So you can have all phases supplied.

I am doing a great deal of testing on the subject but Sarels case study on here is a great education. Power creation & spitting out a pure SINE wave 🌊 is Grid Power. In three phase to the tune of 400 odd volts is the only difference. 

If your Grid tied inverter had this fed then it does not know the difference. By no stretch of the imagination there are some complexities but fundamentals that need following. The "Factor of One" is one of these rules that must be followed otherwise safety & equipment damage is a real threat.

However, with the Pure 3 phase Hybrids around Grid tied inverters are no longer so appealing especially in our unstable grid scenario in SA. They achieve lower Eskom costs & are good for high electricity users that need savings. However, in a Loadshed scenario are pretty useless.

The Infinisolar 15kW inverter I have seen as probably the best bang of all worlds. Blends power & can add up to 22kW of Solar PV & the most impressive part can work without a battery 🔋. This machine though is a lot of money. The more cost effective option is to stack MAX inverters in parallel feeding different phases. In your case the cost calculation will be adding two more Sunsynks Vs the 12kW inverter price.

All that I know is that every 4 months you could afford a new 8kW Sunsynk & slowly get out of the Eskom predator trap. 

You should really start this conversation with a Solar consultant & explore your options. After much talking & digestion of information you will get a solution & one that pays for itself. Your have already a very solid infrastructure & equipment that still has value & can be sold to raise capital for whatever option you want to take. 

87

 

The only reason keeping me from putting the Grid Tie on the Sunsynk output is that one is single phase and the other 3 phase.  I have lots of faith in the Sunsynks and would prefer to stick with them. Now should I go for the 12kw - 3 phase OR add two extra 8kw's ? Funding is not unlimited. 

3 x 8kw Sunsynks will have more capacity, but costs probably 50% more than one 12kw 3 phase. Also unable to do it in stages. Can't add one and another later due to the three phase setup.

The Diehl and Ground array are at the back of my garage - about 30 metres from the Sunsynk & Batteries in my house. Between my garage and house is a sub DB - on the pole where the Eskom feed for my house comes in from our Main supply meter - which is another 100metres further.  The Diehl feeds in 3 phase at this DB  and my Sunsynk takes Single phase from here. The Sunsynk CT is also located here so I can "export" to non essentials on the same phase. I am not currently limiting export, so the Sunsynk and Diehl both backfeed the other two houses on the property - when Grid is on. 

Maybe I should consider the following option as a first step  : Replace the Diehl with another 8kw Sunsynk. Run it Grid Tied and feed into the essential load output of the existing Sunsynk and 24kwh Battery pack -  both on the same Phase.  Later add another 8kw, move everything to the garage and then configure as 3 phase supply off the same Battery pack.

Hope I'm not blabbing.......just trying to give as much info as possible for everyone to "picture" my setup.

  

Consider getting the Extra Sunsynks. Get first one, install it but do not yet do final connection. Get second one and install per available budget. Now connect all. This way you get max flexibility, redundancy and the best cost recovery from your current investment. You also do not get much in the form of disruption of supply. You get to keep on line until just the switchover.

@sarel and @87 dream I really appreciate your valuable inputs. I will consider the options and keep you posted on my progress.

A last question before we provisionally wrap this up . Any suggestions on monitoring my power use and or feedback at our Eskom supply point +- 100m from my house. This is after the two rental houses have absorbed my excess generation.

I want to measure/ log this data and have access to this from my house - to establish how power flows and maybe control loads to keep the balance..

There is a Wifi access point close to this point.

Be careful here. There are energy meters and energy meters here. Some cannot even measure bi-directinal and count both directions as one. So called 4 quadrant metering would likely be required. As an Eskom direct client, I would think you get hit with demand charges and Power Factor is important, active/reactive and real (true) power.

Depends on what you want to do with that info tho. Just display to monitor the situation? Log the data and maybe use it to automate things?

Good quality meters are expensive. This is a good brand, Carlo Gavazzi. There are others. Likely finding the right meter with ethernet or wifi may be a stretch and a search. 
 

 

 

Here be example.

Thinking that this is a journey towards being self sufficient we need to know exactly what we are currently using.

For a start monitor and log to know exactly what the current status is - peak demand  and consumption ( how much and what time of the day) - also generation (feed back of excess) and when during the day.

Later, if possible use the info to switch loads at appropriate times.

Would a Carlo Gavazzi work ? What other equipment and software would I need to work with the meter ?

 

Hi 87,

This looks like exactly what I need.

Where did you source yours ?

8 hours ago, 87 Dream said:

https://a.aliexpress.com/_m0ICwQm

Express Air Shipment is a tad expensive at the moment. If I ship again I will actually include a few of these units. Think you are not the only person interested to get their hands on one of these.

Still under the value of most meters out there. Just wish shipping was at pre Covid prices. Maybe in time the world will get to some normality again. 

87

Thank you for your recommendation.

The monitoring software seems very capable. You can even change dates to coincide with your Utility billing cycle and also has TOU billing functionality.

I've taken the leap and ordered two of these with DHL delivery - First time on Aliexpress🥴

One for the Mains and one for the 3 phase Inverter (which currently doesn't have any logging info that I can process)

That way I should be able to monitor the energy flow in-and-out on one platform.

 

Ok, I see the immediate steps in my Off Grid journey as follows - please correct me where necessary.

1) Measure the current energy requirements accurately. Also what exactly is generated  -how much and when.

2) Get DHW off grid. All stoves are already on Gas - but ovens still all electric. 

3) Replace Diehl Grid Tie with another two 8kw Sunsynks to complete the 3 phase supply - Independance from grid outages

4) Add battery capacity

5) ?

On the subject of battery capacity and generation which is centralized at one point (my house) - Would you stick with that setup  or decentralize and have the extra battery and Inverter capacity split between the two other houses on the property ? 

Then maybe do the 12Kw 3 phase Sunsynk instead and add a smaller 5kw Inverter and PV at each of the other houses.  Both feeding excess into separate phases of the same Micro Grid (Thank you @Sarel 😇) . Thus each house largely self-sufficient but connected. Peaks being supplemented from the main house capacity.

Am I daydreaming ? 

Why drop the Diehl? It’s a more efficient harvester, plus you can build your Micro grid. Except if you want to sell the Diehl, but still…. Also you have redundancy, should one Sunsync need service, as well as extra Solar input capacity. Just curious. 

39 minutes ago, Sarel said:

Why drop the Diehl? It’s a more efficient harvester, plus you can build your Micro grid. Except if you want to sell the Diehl, but still…. Also you have redundancy, should one Sunsync need service, as well as extra Solar input capacity. Just curious. 

That was my initial idea - selling the Diehl to help fund the Sunsynks.

Got it for a good price though (2nd hand but unused) and although not common locally,  its seems like a quality product that comes with a 10 year OEM warrantee.

If we keep that for redundancy, it will require some nifty planning - wiring wise. The Sunsynks operate at 350 V and the Diehl at 550v  currently.