Your September bill dropped. October’s dropped again, and nothing in the business changed.
Most owners file that away as good news and move on.
It isn’t only good news. That drop is a free diagnostic of your operation, and almost nobody reads it. It’s also the cheapest Eskom tariff comparison you will ever run.
It isn’t Eskom going soft on you. April’s increase of 8.76% is still buried inside every rate you pay.
It isn’t your solar either, if you have solar. Panels don’t switch themselves on in September.
It’s the season. Eskom charges winter rates from June to August, and that window closed on 31 August. The low season now runs all the way through to May.
So far, so ordinary. Here’s the part that actually matters.
Those two bills, a winter one and a summer one, reveal the shape of your business. And the shape of your business decides whether your tariff still fits it.
Most firms picked a tariff once, usually when the meter was first installed. Nobody has reviewed it since. Your load changed over the years, but your tariff never moved with it.
Eskom sells electricity two different ways
The first way charges you for when. Power costs a fortune in the early morning and the early evening, and very little overnight. Megaflex, Miniflex and Ruraflex all work like this, and they’re called time-of-use tariffs.
Think of airline seats. Same seat, same aircraft, different price depending on when you choose to fly.
The second way charges you for how hard. Your energy rate stays flat all day, but you pay a heavy monthly fee for the biggest bite you took. Nightsave Urban works like this.
That fee is a demand charge, and it’s measured in kVA rather than kWh. Picture a water pipe. Energy is how many litres you drew, and demand is how wide the pipe had to be. We pulled those two apart in more detail in our guide to Eskom’s winter tariffs.
One tariff punishes bad timing. The other punishes a sharp peak.
What an Eskom tariff comparison comes down to
Here is winter energy on each tariff, priced per 1,000 units, before VAT.
Look carefully at the Nightsave figure. It lands almost exactly on the Megaflex standard rate.
So flat energy isn’t a bargain at all. It’s an insurance policy against expensive peak hours.
Insurance carries a premium. On Nightsave you also pay R332.91 per kVA, every winter month, on your peak demand. On Megaflex that same charge is only R26.29.
Almost every other line on the two bills is identical. Same network capacity charge, same transmission charge, same legacy charge, same service and administration charges.
So the entire decision reduces to just two numbers.
Each unit you burn during peak hours costs R5.43 less on Nightsave.
720.19c − 177.20c = 542.99c, or R5.43 per unit
Each kVA of peak demand costs you R332.91 more on Nightsave.
Divide the second number into the first:
R332.91 ÷ R5.43 = about 61 units
For every kVA of peak demand you carry, you need roughly 61 units inside the peak windows each month. Above that figure, flat energy wins. Below it, time-of-use wins.
A month contains roughly 80 to 90 peak hours, in two blocks a weekday of about two hours each. So 61 units per kVA means running near 70% of your peak, straight through every peak window.
That describes a genuinely busy site. A cold store, a packhouse in season, or a three-shift factory.
Eskom says exactly the same thing in its own words. Its booklet calls Nightsave Urban suitable for high load factor customers. Now you know what that phrase means in rands.
Why summer doesn’t change the answer
You might expect this sum to flip over in summer, but it barely moves at all.
In the low season the Nightsave demand charge drops to R77.88 per kVA. The Megaflex peak rate falls too, and considerably further. Run that same division on the summer figures and you land on about 60 units.
Sixty-one units in winter, and sixty in summer. The seasonal swing is brutal on both tariffs, yet the choice between them hardly budges. That’s useful, because it means you needn’t guess which season to plan around.
The footnote that moves your tariff for you
Now here’s the part that catches people out.
Nightsave Urban and Businessrate both carry one small footnote in Eskom’s booklet. For grid-tied generation a time-of-use tariff is mandatory.
Read that twice. Connect solar to the grid and you cannot remain on either of those tariffs.
So a solar project can move your tariff whether you asked it to or not. Your energy bill falls, and your entire charge structure changes underneath you at the same moment.
If nobody modelled that properly, the payback figure you were shown is wrong.
Which tariffs can you actually be on?
This next part surprises almost everybody. You don’t get a free choice of tariff.
Megaflex requires a notified maximum demand above 1 MVA. That’s the capacity you’ve contracted with Eskom, and it’s printed on your bill in kVA. It’s worth understanding properly, because it also drives the one charge peak shaving can’t reduce.
Below 1 MVA, Megaflex simply isn’t available to you. Miniflex is the time-of-use option instead, and it runs from 16 kVA up to 5 MVA.
Nightsave Urban starts at 25 kVA, and it permits no grid-tied generation. Businessrate covers 100 kVA and under, permits no grid-tied generation either, and carries no demand charge whatsoever.
Ruraflex serves rural supplies from 16 kVA, at 22 kV or below. It has the widest gap between peak and overnight rates of anything Eskom publishes.
But Ruraflex charges more for the network, at R52.55 per kVA monthly against R39.13 on Megaflex. Its network demand charge is also billed per unit, in every single period. Shaving a peak doesn’t touch that charge. Only using less does.
Who this post isn’t for
If you’re on Businessrate and solar isn’t on the table, stop reading here.
Businessrate carries one flat energy rate and no demand charge at all. There’s nothing to time and no peak to shave, so comparing tariffs will tell you nothing you can act on.
The day solar enters your plan, come back and read this again. That footnote is about you.
What to do this week
- Find your tariff name. It’s printed somewhere on your bill, and our line-by-line walkthrough shows you where.
- Find your notified maximum demand in kVA. It’s usually on the same page.
- Put your July bill beside your September bill. Compare the energy lines first, then the demand lines. That’s your seasonal shape, measured for nothing.
- Ask yourself the honest question. Can you move real load into the overnight window? Not in theory. Actually.
- Email Eskom’s pricing desk on electricitypricing@eskom.co.za and ask which tariffs your supply and your demand qualify for. Ask what the change process involves as well. This step costs you absolutely nothing.
- If solar or a battery is on the table, have the tariff modelled before you sign anything.
One warning before you act on any of it. We can’t tell you the notice period for a tariff change, or how quickly you could switch back. Those details sit in Eskom’s NMD rules, which shift with the regulator’s approval. Ask before you commit, rather than afterwards.
Questions business owners actually ask
How do I find out which Eskom tariff I’m on?
It’s printed on your bill, usually somewhere near the account number. Look for a name like Megaflex, Miniflex, Nightsave Urban, Businessrate or Ruraflex. If you buy your power from a municipality instead, you’re on a municipal tariff and these names won’t appear anywhere.
Can I just switch to a cheaper Eskom tariff?
Not freely. Each tariff carries rules about supply area, voltage and notified maximum demand, and you may simply not qualify. There’s a formal process behind it as well, set out in Eskom’s NMD rules. Email the pricing desk and ask what applies at your own point of supply.
Which is cheaper, Megaflex or Nightsave Urban?
That depends on your load shape rather than your size. Nightsave suits a site running hard and steadily right through the peak windows. Megaflex suits a site that can push real load into the overnight hours, and it also requires more than 1 MVA of notified demand.
Does installing solar change my Eskom tariff?
It can force one on you. Eskom’s booklet says grid-tied generation makes a time-of-use tariff mandatory, so Nightsave Urban and Businessrate both drop off the table once you connect. Model the new tariff before you buy the panels, not afterwards.
I buy my electricity from the municipality. Does any of this apply?
The principle does, but the rates don’t. Megaflex and the rest are Eskom-direct tariffs, and municipal customers sit on their own separate schedules. Those schedules rose on 1 July rather than 1 April. eThekwini’s business electricity went up 9%.
Will a battery fix a tariff problem?
Sometimes, and sometimes it’s the expensive way round. A battery is good at shifting energy and cutting a peak, but it cannot make you eligible for a tariff you don’t qualify for. We set out what batteries do and don’t fix in our piece on peak shaving savings. Check the tariff first, because asking about it costs nothing.
Start with the two bills you already have
Your two bills are already sitting on your desk. Winter in one hand, summer in the other. The gap between them tells you more about your tariff than any brochure ever will.
If you’d like us to read them with you, get in touch.
Where these numbers come from. All rates are Eskom’s published 2026/27 non-local-authority tariffs, effective 1 April 2026, for a supply of 500 V or above and below 66 kV in the Transmission zone up to 300 km. Your own band may differ. Rates and eligibility rules: Eskom, Schedule of Standard Prices for Eskom Tariffs, 1 April 2026, and Eskom, Tariffs and Charges Booklet 2026/2027, both published at eskom.co.za/distribution. Figures exclude VAT unless stated. The 61-unit and 60-unit breakeven figures are our own arithmetic on those published rates, and they compare the active energy and demand charges only — every other charge is the same on both tariffs. They are a guide to which way to look, not a substitute for modelling your own metered data.
