The number that decides whether your embedded generation application is approved is the inverter's rated AC output, measured against a percentage of the connection capacity already recorded against your property — not the size of the solar array on the roof. Most municipalities express the cap as a share of that connection capacity, and 25% and 50% are the two figures I keep meeting, though some publish flat kilowatt ceilings instead and treat single-phase and three-phase properties differently. The connection capacity is on your municipal bill, or one phone call away from the electricity department, and everything else about system size falls out of it as arithmetic.
The bill on the left, the quote on the right
I do this at the kitchen table, and I want you sitting next to me with two pieces of paper in front of you. On the left, a municipal bill. On the right, a solar quote. Before I open the quote, I go hunting through the bill for the connection — sometimes it's a line described as supply capacity, sometimes it sits inside the tariff description, sometimes it's just an amp figure printed next to the meter number. The label moves around from one municipality to the next, which is exactly why people skim past it. What you're after is the size of service the municipality has agreed to supply you: an amps figure, a kVA figure, or both.
If it isn't printed, it isn't a secret. The electricity department keeps it on the property's record. I've asked by phone and by email, and once I've given the account number and the street address, the answer comes back quickly enough. The mistake is doing this after you've signed something.
Now convert, because the limits are usually written as a percentage and we tend to read amps. Multiply amps by volts. A 60 A single-phase connection at 230 V lands near 13,8 kVA. An 80 A single-phase lands near 18,4 kVA. A three-phase property on 3 × 63 A at 400 V comes out around 43,6 kVA. Treat those as illustrations of the arithmetic rather than a reference table — your own bill is the document that counts, and older properties often carry a connection capacity that no longer matches what is physically there.
Then apply the percentage. On a 13,8 kVA single-phase connection, 25% gives you roughly 3,45 kW of generation capacity, which is a 3 kW inverter and very little else. At 50%, the same connection allows about 6,9 kW, which fits a 5 kW inverter comfortably and rules out an 8 kW machine. Move those same percentages onto that 43,6 kVA three-phase connection and you get 10,9 kW and 21,8 kW. That gap is the whole reason a three-phase property can host a system its single-phase neighbour can only dream about, and it's why the first question an experienced installer asks isn't about your roof.
The inverter is the gate, the array is the fuel
Here's the distinction that trips people up, and it's worth getting straight before you speak to anyone. The array is what sits on the roof. The inverter is what converts DC to AC and pushes it into your wiring and, if you're allowed, onto the municipal network. The municipal calculation uses the inverter's AC output, because that describes what can appear at the point of connection at any instant. The array never enters the sum.
That single fact is where panel oversizing lives. It is entirely normal design practice in South Africa to hang more panel capacity on an inverter than the inverter's own rating — a DC-to-AC ratio somewhere in the region of 1,2 to 1,4 is common, because panels spend most of their life well below nameplate output and the array only occasionally produces everything it can. Under many municipal rules that's fine, and it's fine precisely because the extra panels don't change the number the municipality cares about. Swap that 5 kW inverter for an 8 kW unit and the panel count can stay identical, but you've just changed the number that decides whether your application stands.
Read the datasheet properly. Inverters carry a nominal or rated AC output and a separate maximum AC output, and those are not the same figure. Some application forms ask for one, some for the other, and NRS 097-2-1 describes inverter behaviour on the network in its own language again. If a form asks for maximum AC output, quoting the nominal figure and hoping is not a strategy.
Where the extra paperwork starts
Past a certain size, some municipalities want more than a completed form. A load flow study or network impact assessment checks whether the local network can absorb what you're proposing, and it's usually at the applicant's cost, sometimes bundled into the application fee. The threshold varies between municipalities and, in practice, between networks inside the same municipality — a suburb at the end of a long feeder can be treated more cautiously than one sitting beside a substation. So a system that sails through on one street can stall four blocks away without anything about the house being different. That isn't bureaucracy for its own sake; it's the municipality protecting the voltage of everyone downstream of you.
What happens when you go over
Exceeding the allowed limit doesn't produce a warning letter and a grace period. It produces a refused application, or an approval that gets revisited later, and the system has to change before it can be switched on legally. The municipality owns the meter, so it has a front-row seat. I've seen the aftermath of that: a completed install sitting idle while the owner works out how to fit a smaller inverter, with the cost of the correction landing entirely on whoever signed the quote.
There's a quieter version of the same trap — systems that were never registered at all. They run fine for years, and then a property sale, an insurance claim or a meter replacement turns the missing approval into a problem that has to be solved with an installer who may no longer be trading. Keep the approval letter in the same folder as your CoC and your latest bill. That folder is worth more than any of the marketing material that came with the system.
Two more ceilings the municipality doesn't care about
The municipal limit is only one of three ceilings on system size, and it's the one people leave for last. Roof space is the second — orientation, pitch, shading from the neighbour's tree, the patch the geyser vent occupies. Budget is the third. Neither has anything to do with what the municipality will approve, and neither can be traded against it. A generous roof does not buy you a bigger limit, and a bigger budget doesn't either.
Which is why I work the order backwards from how most people do it. Connection capacity first. Percentage second. Inverter AC output third. Array last, sized to whichever inverter you've settled on and to the roof you actually have. Doing it the other way round — glossy quote first, municipal limit whenever someone gets round to it — is how a household ends up owning a machine it cannot register.
And when you're ready, ask the electricity department for the limit in writing, by email, with your account number in the subject line. What comes back is worth more than any number a salesperson quotes you across a table.
