I am looking to install a grid-tied system in a house we moved into a few months ago. It seems that now over the last few months we average about 800kWh of power consumption a month, which I anticipate will go about to +-1000kWh in winter.

My thoughts on an initial installation are:

• 12KW Hybrid Inverter

• 12 Panels (roof is north facing. There are tall trees on the western side of the roof that may cause shade in the late afternoon, so I will install it on the eastern end of the north facing roof)

• 10KW Batteries.

Other info:

• I have a single 3KW geyser;

• Stove is gas, oven is electric;

• No airconditioning as yet, but probably a couple inverter units to come soon.

Questions:

1. What are the brands to go for on the inverter, batteries and panels?

2. Is 12KW inverter right, or could I go for 8KW?

3. Any general insight / advice is welcome.

Hi Justin91

I see you have given the power consumption for a month. this is handy; however, the figure needed for an inverter installation is how much maximum power will be used at any one time for the inverter to be effective. A bigger inverter is always better if one can afford it, as when it is under load, if you are using it, it is better to see the power usage up to 75% or less. Seeing that you are going to connect the aircons, it would be better to go for the larger unit.

As far as the make of the inverter, it is up to you, as there are many good brands on the market. As I read many posts, it is not difficult to pick out which ones have a good reputation. I can only recommend a Sunsynk or Deye as I have an 8KW Sunsynk and had no problems for six years. Deye, I believe, has better support.

12 panels seem a bit lite for the inverter chosen, as it looks like a total of about (12X550W) 6600W max. You could install about 11000W, even with an 8kW inverter. In Winter and Summer, if you install the aircons, you could save a lot during the day if more panels are installed. As far as make, again, it's up to you to check the posts. After reading a lot, I gained some valuable information. The best Panels are N-type panels. P-type panels are doped with Boron, and N-type panels are doped with Phosphorus. I am sure a lot of installers do not even know the difference. N-Type panels have a better output (about 2%) and last longer. The majority of panels sold are P-type, as they have been around longer. I did not know this before I bought my panels.

As far as the batteries go, 10KW could last a fair time if you did not use the aircons and limit the geyser during a power outage. A better bet is 20 kW with the extra panels if you can afford it, to ensure power during overcast days.

I suppose it's all up to the budget you have. It is a good time to install as the prices at the moment are still good, and I am sure loadshedding will be back and I see today it is.

Edited April 24, 20251 yr by Peter Topp

I myself, am a Solis fan.

When it comes to sizing the inverter, there are 2 view points

1. It needs to cover your max current usage (kettle + airfryer/oven + aircon), this is where the 6/8/12kwh comes in.

2. The inverter should be able to properly utilize your initial panels, with the option to expand later on.

For me personally, I use around 1000kwh s month on average, I am using the Solis S6, with 24 × Jinko panels. I have not once tripped the inverter (geyser runs for an hour between 1600 and 1700. Pool only kicks in when the pv forecast is still good for the next hour, and battery is full.

Now, with keeping thise points in mind, ai will later add another 6Kw version, for redundancy and as well to install an sdditional 2 pv strings.

When it come to batteryb, it should be eoughly 1.5x your daily usage

I have a 5kW inverter and it generated 975kWh last October. In my opinion an 8kW inverter can probably meet your needs most economically. The questions you should be asking is how much money should I be spending on energy efficiency, how will I do energy management, what are my essential loads and how much am I willing to spend on luxury (batteries)?

Thanks for the feedback so far.

Out of interest - are most people trying to connect their entire house as essential and manage when their geysers / pool pumps etc. run, or is it still preferable to put geysers etc. onto non-essential, but then, are you not forgoing the saving on those items as they will always draw grid power?

24 minutes ago, Justin91 said:

Thanks for the feedback so far.

Out of interest - are most people trying to connect their entire house as essential and manage when their geysers / pool pumps etc. run, or is it still preferable to put geysers etc. onto non-essential, but then, are you not forgoing the saving on those items as they will always draw grid power?

Depends on system size,

When I started with a single 5kW unit, geysers/pool pumps/stove remained on non-essentials and were back-fed with Solar by the inverter's ability to zero-export-to-CT through the grid port: this meant I didn't need to worry about the capacity constraints of the inverter since if we exceeded it's limits/production, the balance simply came from the grid.

Keeping these non-essentials fed by excess PV like this was critical for return-on-investment on the system, since they're a typical home's biggest power hogs.

When we parallel'ed our second unit, we then moved all these non-essentials onto the inverter's Auxiliary port (which is still constrained by the inverter's UPS/load capacity - albeit now double thanks to the second one), to let them run if there's spare battery and/or PV when the grid is down.

In retrospect, with our single 5kW we could've probably swapped the one geyser's element down to 2kW and then been OK moving just that geyser to the essentials/aux, for coverage during extended grid-outages; at the cost of slower water heating due to the smaller element.

The other possibility is you can put 'non-essentials' onto change-over switches to swap them between non-essentials (for most of the time when you don't want to be bothered by limits) and essentials (when the grid goes down and you need hot water!) for a best-of-both-worlds approach if you don't have tons of spare inverter capacity.

Edited April 25, 20251 yr by JayMardern

1 hour ago, Justin91 said:

Out of interest - are most people trying to connect their entire house as essential and manage when their geysers / pool pumps etc. run, or is it still preferable to put geysers etc. onto non-essential, but then, are you not forgoing the saving on those items as they will always draw grid power?

It depends :-)

My outbuildings and my pool pump are not backed up. On a sunny day with the grid up the inverter will run the non-backed up circuits with surplus PV. On a non-sunny day it will use battery, then grid for those circuits. So I still save on them, but I lose them when the grid goes down, even if it's sunny. As suggested in this thread I am thinking of a change over switch so that we can use the laundry when there's load shedding (at present we run it off an extension cord).

For water heating I have a heat pump. This is more efficient than a conventional element and draws a lot less, so I can get away with it on the backed up side.

There is no one right way. The household needs to decide what is essential to them and what they can live without. But the big loads are generally geyser, stove and kitchen appliances. TVs, lighting, wifi, electric fence don't draw much. Kettles and microwaves do, but not for long. Dishwasher... check the manual and see what it consumes on different programs.

There are limits that you need to be aware of
1) The sustained output of your inverter
2) The sustained output that your battery can deliver
3) The capacity of your battery.
4) The C rating of your battery,

Good batteries these days are 1C. That means you can use the entire capacity of the battery in one hour (and recharge at the same rate). This means that a 10kWh battery can deliver 10kW at any given time, but you probably don't want to do that for a whole hour.

Try to do as much as possible during the daylit hours when you have free electricity off the roof. EG I never run my dishwasher at night. It runs in the morning when I have lots of PV. I try to do all the heavy lifting (so to speak) during the day, so the loads at night are minimal and so we easily get through the night on the battery.

Finally, most systems have a way to reserve a portion of the battery for use only when there is no grid. On my system I have this set to 40%. It will not discharge the battery past 40% when there is grid power. So I go into any load shedding our outage with at least that much power available.

Edited April 25, 20251 yr by Bobster.
Extra detail

I can vouch for Luxpower Inverters and Cyclone batteries.

Luxpower units are 5kw and sell for +-R8000 each (City of Cape Town approved as well). What could work out cheaper is using 3 of these, giving you 15kw of installed capacity at +-R25000.
These inverters run 2 x MPPT's, each with a maximum of 4400w input, totalling 8800w per inverter.

The Cyclone batteries are supported locally by their importer Solarway and cost around R13000 per 5.12kw battery, with 10 year warranty.

What may be more suitable is to covert your geyser to solar with a fall back to heating from your inverter. Thats what I do and its dropped my consumption massively. I've recently had my geyser hit 75 degrees C.

19 hours ago, Bl4d3 said:

I can vouch for Luxpower Inverters and Cyclone batteries.

Luxpower units are 5kw and sell for +-R8000 each (City of Cape Town approved as well). What could work out cheaper is using 3 of these, giving you 15kw of installed capacity at +-R25000.
These inverters run 2 x MPPT's, each with a maximum of 4400w input, totalling 8800w per inverter.

The Cyclone batteries are supported locally by their importer Solarway and cost around R13000 per 5.12kw battery, with 10 year warranty.

What may be more suitable is to covert your geyser to solar with a fall back to heating from your inverter. Thats what I do and its dropped my consumption massively. I've recently had my geyser hit 75 degrees C.

Hi

As far as I know and have checked, no off-grid inverters are now being approved.

"The City of Cape Town was the first of the major metros to publish a list of approved inverters for grid-tied solar and backup systems. While the city initially allowed off-grid inverters like the customer's Must model and various brands of Axpert inverters, it changed to hybrid-only effective 1 October 2023.11 Mar 2025."

Edited April 26, 20251 yr by Peter Topp

6 hours ago, Peter Topp said:

Hi

As far as I know and have checked, no off-grid inverters are now being approved.

"The City of Cape Town was the first of the major metros to publish a list of approved inverters for grid-tied solar and backup systems. While the city initially allowed off-grid inverters like the customer's Must model and various brands of Axpert inverters, it changed to hybrid-only effective 1 October 2023.11 Mar 2025."

From the City of Cape Town approved inverter list that was last updated on 1 April 2025: https://resource.capetown.gov.za/documentcentre/Documents/Forms%2C%20notices%2C%20tariffs%20and%20lists/Approved%20Photovoltaic%20%28PV%29%20Inverter%20List.pdf

Additionally, I have a SNA5000 installed which was just approved by CoCT

Hi

looks like I checked in March which I downloaded and not the updated list. It is good news for some.

I was a bit unsure of the understanding of off-grid but now I understand that it is not a off grid inverter.

Off grid meaning it is seperate from the grid. So certain approved hybrid inverters that are tied to the grid without feedback are approved.

I see it reads grid tied hybrid (source with batteries) with no export.

.

9 hours ago, Peter Topp said:

Hi

As far as I know and have checked, no off-grid inverters are now being approved.

"The City of Cape Town was the first of the major metros to publish a list of approved inverters for grid-tied solar and backup systems. While the city initially allowed off-grid inverters like the customer's Must model and various brands of Axpert inverters, it changed to hybrid-only effective 1 October 2023.11 Mar 2025."

We need to be clear on what we are saying in terms of inverter terminology and especially how it is applied.

Let us break it down:

The NRS097 regulations require that any inverter connected to the grid (even if just feeding your own loads) must have certification, anti-islanding protection, and 1 usually a double disconnect switch (DDS) system built in.

Voltronic inverters (like Axpert, Mecer, Kodak OG series, etc.) are not NRS-approved because they don’t have this certification — but if there is no grid connection at all (i.e., you are truly off-grid), you do not need NRS approval.

In short:

Off Grid.

If you have NO Eskom feed, and you are running purely off batteries + solar, you can use a Voltronic or any other non-certified inverter without breaking any rules.

If there is Eskom (even if you don’t intend to export to it), then by law your inverter must be on the approved list

Hybrid inverter.

A hybrid inverter can manage solar panels, batteries, and the grid at the same time and needs to be on the approved list.

Bi directional inverters.

Will normally be in the approved list as it employes a ct coil and limiter(dds) to controll export to the utility grid.(Sunsynk, Deye,Solis, Goodwe ect.)

Luxpower tick all the boxes and is NRS approved due to the fact it employs a grid limiter and double disconnect switch.

8 hours ago, TaliaB said:

If you have NO Eskom feed, and you are running purely off batteries + solar, you can use a Voltronic or any other non-certified inverter without breaking any rules.

There should be a list of inverters that can be used with Eskom but that are off-grid inverters. There is no UPS list that I am aware of but everyone can use a UPS. I am confident CoCT won't win a court case against someone that has an inverter that can't blend in solar to load... I have gone for a 48V charger to seperate my off-grid system but still draw Eskom energy.

4 hours ago, frivan said:

There should be a list of inverters that can be used with Eskom but that are off-grid inverters.

As so often it'll become a game of definitions. What does "off-grid" mean? My understanding of the Axpert is that if load > PV then the inverter will shut down and switch all the demand to Eskom. It can't do the blending that newer, "hybrid" inverters do. So is an Axpert really an "off-grid" inverter? It can't feed back into the grid, which removes one potential sticking point.

Of course any inverter that is used where the grid connection is not presents is off-grid and so doesn't need to be certified for SSEG purposes.

4 hours ago, frivan said:

There is no UPS list that I am aware of but everyone can use a UPS.

Because a UPS doesn't feed back and is usually a plug in device. So it's more like an appliance as regards the grid. It's like a geyser or a deep freeze, and it gets silly quickly if we start imposing regulations about how long such a device must wait before it reconnects to the grid. Well what if I go out when there's load shedding and I leave some standard lights plugged in? Do the electricity police come and give me a ticket?

Hmmmm,,,, maybe it's better not to put ideas into heads.

4 hours ago, frivan said:

I am confident CoCT won't win a court case against someone that has an inverter that can't blend in solar to load... I have gone for a 48V charger to seperate my off-grid system but still draw Eskom energy.

Maybe not. But who wants to get into that position? Lawyers don't come cheap. The person in the street is going to have to break into the piggy bank. COCT will fight it with the best legal team money can buy. Because if they lose that case a precedent they don't want will have been set. So it's worth it to them to fight it as hard as they can. Meanwhile the plaintiff's legal bills mount up.

2 hours ago, Bobster. said:

Maybe not. But who wants to get into that position? Lawyers don't come cheap. The person in the street is going to have to break into the piggy bank. COCT will fight it with the best legal team money can buy. Because if they lose that case a precedent they don't want will have been set. So it's worth it to them to fight it as hard as they can. Meanwhile the plaintiff's legal bills mount up.

Yes, I figured death by lawsuit will be the approach and kill the little guy. That is why we need to define an approved off-grid inverter and stick it to the oppressors:

Any inverter that has diodes on the grid input side is an approved off grid inverter. Such inverter may have a grid bypass, provided that PV cannot be injected into the AC circuitry of the inverter in this mode.

Why would CoCT only define the expensive solution? Perhaps they want to keep the poor poor.

5 hours ago, frivan said:

Why would CoCT only define the expensive solution? Perhaps they want to keep the poor poor.

I don't think the technical regulations are theirs. Those are drawn up by a national body and all utilities & municipalities have to fall in line. Like everybody has to fall in line with the codes for the wiring of a house. What happens with metering & tariffs is their business, but not the technical side.

I'm not saying that makes it OK. I heard from an installer last week who told me about arguments installers & electricians have had with SANS over regulations that, he says, have no reasonable justification. So I'm saying that it's not COCTs fault or even Eskom's fault, we need to get annoyed with somebody at national level.

I don't feel able to comment on the technical aspects, but I know there is unhappiness about the regulations.

When COJ come to take your prepaid meter away because you have solar, THEN you can get fed up with COJ.

10 hours ago, Bobster. said:

I don't think the technical regulations are theirs.

Don't get me started on the national bodies. I don't even think SANS 10142-1-2 has been officially implemented. However, if CoCT wants to set the trend with a list of grid compliant inverters, they must do the same for off-grid inverters. Cape Town will only be better off if the people in Khayelitsha are allowed the same sunshine as the people in Clifton.

1 hour ago, frivan said:

Don't get me started on the national bodies. I don't even think SANS 10142-1-2 has been officially implemented. However, if CoCT wants to set the trend with a list of grid compliant inverters, they must do the same for off-grid inverters. Cape Town will only be better off if the people in Khayelitsha are allowed the same sunshine as the people in Clifton.

Yes. This is a problem. You can save on your bill, reduce your footprint, decrease your dependency on the grid. But only if you have the money.

Though City Power in Jhb provided a small solar farm for a religious community in Alexandra who don't care for grids because they see it as a connection to Babylon (I think that's the term used). So that community now gets solar power. I don't know what payment arrangements were made.

I'm willing to bet that somebody has tapped into the output side of that system. If they'll tap in to City Power's grid, they'll tap into any grid.

Poor @Justin91 . We've taken his enquiry way off topic.

To pull things back on topic.

Inverters:

• Sunsynk and Deye are pretty much the same, however local support for Deye is horrible should anything go wrong.
  These inverters do offer some extra features that you may like.
  However they are relatively expensive with 5kw versions starting at R16000
  A 12kw Deye will set you back about R35000 with a 12kw Sunsynk at R43000

• Luxpower has entered the space to offer better features and better reliability than the Axpert type inverters, while conforming to NRS standards
  They have managed to do this while maintaining a low price point.
  There is a local Luxpower agent however support it best through the store you buy it from, best look into who offers the best support.
  Pricing starts at R8500 for a 5.5kw however there is the more recently released SNA12000 12kw for R20000. This SNA12000 has not yet made it on approved inverter lists but likely will.

• Growatt, Axpert, Mecers TheSunPays, I recommend avoiding these as they are relatively basic, don't conform to standards, and have a high failure rate, mainly with the MOSFETs failing.

Inverters can normally be paralleled together to increase capacity.

Batteries:

Steer clear of new / unknown brands and stick with known brands that are supported locally.
Brands to consider are Dyness, Deye, Sunsynk, Freedom Won, Cyclone, Hubble. Some important factors when looking at batteries:

• Output rating - You will want at least a 1C rated battery when looking at 5kw units. This ensures you will be able to output at least 5kw. Some larger 10kw batteries might be rated to 0.75C, allowing you to output 7.5kw.

• Warranty - Some brands only offer 5 years, most 10 years, some only 2 years. You'll want to see who offers the longest warranty, but also more importantly, will that support still be there in 10 years. This is why its critical to go with one of the main brands who have a strong following, to ensure you will have support down the line.

• Price - Price is coming down rapidly. You can now pickup a 5kw battery for R13000, compared to R26000 a year or 2 ago.

Solar Panels:

Only buy from reputable sellers. There are lots of fly-by-night sellers advertising 600w panels, only to deliver 300w units which have been relabeled as 600w.
Well known and good brands are Canadian Solar and JA Solar.
Both offer similar pricing, similar warranty, and similar guarantees, and both brands have a very good following in South Africa.

Nowadays, you can pickup a 600w panel for R1500 new. Insanely cheaper than a couple years ago.

Personally, what I would do is the following:

3 x Luxpower SNA5000's - R25500

3 x Cyclone F5 5kw batteries - R42000

18 x JA Solar 600w - R27000

This would give you considerable room for expansion while giving you some extra storage.

22 hours ago, frivan said:

Any inverter that has diodes on the grid input side is an approved off grid inverter. Such inverter may have a grid

Is this the way off grid inverters are designed?

My latest thoughts after having read through the above:

• Deye / Sunsynk - These are the two brands I recognise. Solis and Luxpower I have heard of, but I have never seen them in action. What struck me though, is the Deye support in SA really not that great? Are Solis and Luxpower really worth it? I would like to get a lot of it automated at some stage.

• 8KW vs 12 KW inverter - We are a household of 4 plus the domestic worker there during the day only. 2 small kids and 2 adults. I would like to get the geyser onto the essential side of things, even if it means putting in a 2000W element. If I do that, surely 8KW would be fine? I do have a 0.75KW pool pump which runs for 4 hours a day. My stove is gas. I am also looking to put in 3 aircons, but they will be inverter type R32 energy efficient ones (likely 2x 9000 BTU and 1x 12,000 BTU). I technically have two geysers plumed in series, but generally I only run one. However, what I could do I suppose is run one after the other during the day in order to ensure that there is enough hot water for everyone, but I am never pulling more than 2000W. Washing machine, dishwasher, kettle, iron would be the other usual high-power suspects. Would 8KW manage?

• Panels - I will stick to the trusted brands, N-Type. Likely 12-16 panels.

• Batteries - Hubble and Dyness are again the two I recognise. Cyclone definitely seems cheaper, but not common. Any other thoughts or suggestions? Due to cost I might start with 1x 5KW to get through the night, and another 1-2 at a later stage.

• Assuming I purchase the inverter, panels and batteries - how much (ballpark) can I budget on for other materials and installation. I have a standard pitched roof.

2 hours ago, Justin91 said:

Assuming I purchase the inverter, panels and batteries - how much (ballpark) can I budget on for other materials and installation. I have a standard pitched roof.

Consider the battery & inverter as a pair. Make sure they can talk to each other. Don't take for granted that they can.

When my system was installed I had a different brand of battery than I have now. There were various problems which left me concluding that having to restart the system at least once a week was just the way things were. A recurring problem was that the inverter would stop recognising the presence of the battery.

Long story short: the installer recommended a switch to Freedom Won LiTE. This was a game changer. Now BMS & battery got on & the system was stable. When the cable from the BMS was plugged into the inverter the BMS took over & manipulated the settings on the inverter to be what it wanted.

So be aware of that. Ask those questions. In my case Goodwe are not aware of Freedom Won which is a local brand, but Freedom Won know about Goodwe & the two get on just fine.

On 2025/04/28 at 1:24 PM, Scorp007 said:

Is this the way off grid inverters are designed?

On three phase systems one can use 6 diodes to create a DC bus. I am not sure about single phase systems.