Jump to content

Grid tie inverter and ac coupling


Tariq
 Share

Recommended Posts

Have been reading and watching overseas videos on ac coupling, is this viable in South Africa. I was thinking of getting a grid tie inverter, at this stage and in the future , hook up an ac coupled system, if the need arises, I already have a 1 kva Axpert that handles critical loads at present 

Link to comment
Share on other sites

56 minutes ago, Tariq said:

Have been reading and watching overseas videos on ac coupling, is this viable in South Africa. I was thinking of getting a grid tie inverter, at this stage and in the future , hook up an ac coupled system, if the need arises, I already have a 1 kva Axpert that handles critical loads at present 

Is this specifically to reduce your electricity bill?

What about FIT?

Link to comment
Share on other sites

talked to a person at CoCT, , regarding grid tied feed in, according to him it would take nearly 300 Kilowatt hours just ti break even with the high feed in tariff, so for my small scale system would not be feasible to have feed in

talked to Solaradvice, according to them the Solis won't to talk to an  inverter/charger, some of the other makes are out of my budget. I currently have a 1 kw Axpert running all the lights, fans , tv. etc, then use a grid tied ( non feed in for the big loads, pool pump, aircon, geyser on a timer, tumble dryer, washing machine, etc during sunny days, do you all think this is feasible

Link to comment
Share on other sites

1 hour ago, Tariq said:

Solis won't to talk to an  inverter/charger

If you plan on feeding into the grid, then it doesn't have to talk to anything. You simply let the surplus flow into the grid.

I also believe it has its own current clamp  for limiting feed-in to zero, so it will still work just fine. The Axpert can just charge from the grid, and the Solis will notice this import using its current clamp and feed in power to cancel it.

The only downside is that if the grid goes down, then so does your PV. But you know that 🙂

I believe the Solis can do frequency dependent power reduction, so it will work in an off-grid scenario with other capable inverters (Victron, MLT), should you aim for something that can be reused in future... BUT... Solaradvice is correct, it is not terribly well supported. You'd be better of with a Fronius or an ABB...

(except Fronius has dropped off the CoCT list due to lack of 2017 NRS097 certification, which sucks a bit, I have no idea about ABB).

(edit: OK, only ABB on the current list is the PVS-100-TL... which is a big old 100kw three phase beast. So SMA would be your next best bet).

Edited by plonkster
Link to comment
Share on other sites

Hi Plonkster,

   Have another scenario for you, what about a VM III,( which can run without batteries), price wise it is the same as a Solis,  run it essentially like a non feed back to the grid Solis and if I need be, at a future date, can always add batteries and the small Axpert solar inverter powers the essentials as always.

Sound crazy or viable, maybe you can guess, don’t have the budget for expensive stuff

Link to comment
Share on other sites

20 hours ago, Tariq said:

talked to a person at CoCT, , regarding grid tied feed in, according to him it would take nearly 300 Kilowatt hours just ti break even with the high feed in tariff, so for my small scale system would not be feasible to have feed in

Please explain. Does CoCT charge YOU (instead of crediting you) for FIT?

Link to comment
Share on other sites

2 hours ago, Richard Mackay said:

Please explain. Does CoCT charge YOU (instead of crediting you) for FIT?

Due to South African legislation that assigns sole buying rights to Eskom, the municipality cannot buy electricity from you. Cape Town is using a loophole: Instead of paying you for your electricity, they rebate you on whatever you buy from them. This rebate is essentially the same as a FIT, but has some caveats: You will never get any money from them, and you have to remain a net consumer. There is also a fee that is charged for feeding into the grid.

The fee charged for feeding in is the stumbling block. The official reason for this is that you are using CoCT infrastructure (transformers and transmission lines) to "sell" your product, and therefore have to help pay for its upkeep. The amount of electricity you have to feed in to get a large enough rebate to pay for this additional fee often makes it unfeasible.

Link to comment
Share on other sites

18 minutes ago, plonkster said:

The fee charged for feeding in is the stumbling block. 

COCT is really making it difficult.

This explains it a bit: Fair tariffs

Tariffs  So you need to feed back 16kWh to cover your fixed fee tariff ?

How do you do that and cover your own usage and keep a net usage on a 3.5kW system ?

SSEG tariffs.JPG

Edited by Pietpower
Link to comment
Share on other sites

The City of Cape Town introduced a second Feed-In tariff that is a bit more user-friendly - see the "Residential Small Scale Embedded Generation 2" in the attached document.

This works out at R85.00 more than the standard monthly "Network Access" fee, so you need to feedback 108kWh/month or roughly 3.6kWh/day to offset this increased fixed cost.

The only way this will work to your financial advantage is to maximise your feedback during summer months to try and offset your increased usage during winter months. Remember that you cannot be a net-exporter over any 12-month window. 

However, it is worth taking note of section 10.3 of their Supplemental Contract:

Quote

The City reserves the right to make amendments to the tariff as stated and does not warrant the financial viability of the customer’s embedded generation installation.

 

Electricity Consumptive Tariffs 2019-2020.pdf

Link to comment
Share on other sites

1 hour ago, plonkster said:

The fee charged for feeding in is the stumbling block. The official reason for this is that you are using CoCT infrastructure (transformers and transmission lines) to "sell" your product, and therefore have to help pay for its upkeep. The amount of electricity you have to feed in to get a large enough rebate to pay for this additional fee often makes it unfeasible.

I found the same in Jhb. I could export. They don't pay rebate you very much, but it would make some difference. BUT I'd have to convert to the feed in tariff and that includes a fixed monthly fee and so unless I have a Koeberg on my roof (and I don't) it won't be worth my while.

My reading of the situation is that COJ don't want to minimise the loss  of revenues, so they have created a situation where they can say "yes, of course you can resell your surplus power", but they know that nobody's actually going to take them up on it.

Link to comment
Share on other sites

And from what the person at CoCT told me the net meter and installation is between R15,000 and R18,000 , so decided the heck with grid tied and go with a off grid set up, so ordered a VM III , which can run without batteries, blending ( hopefully. 🤔🤔 ) solar and pv 

And, according to the same person, It will be years before the municipalities will be able to buy electricity from ipp’s, if at all, due to the legal stuff, guess the president’s statement is wishfull thinking, like everything else

Edited by Tariq
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...