Your July bill is on the desk. Same machines. Same shifts. Same tonnes out the door as June.
The number is thousands higher.
You didn’t use more electricity. You used it at a different time of day.
That’s most of the story. The rest is the Eskom tariff structure, printed on your own schedule. Almost nobody reads it.
First, Rule Out the Obvious
It isn’t load shedding.
It isn’t the annual increase either. That landed on 1 April, at 8.76% for Eskom-direct customers. One percentage, across the board. It can’t explain a jump this size.
And it isn’t your average rate.
There’s no such thing as your average rate. That’s the part worth sitting with.
Your Eskom Tariff Structure Is Not a Price. It’s a Set of Levers
Open Eskom’s 2026/27 Schedule of Standard Prices at the Megaflex page.
Megaflex is the standard time-of-use tariff for bigger industrial sites. Time-of-use means the price of a unit changes with the hour.
Think of the petrol price. It moves on a date you can see coming, so you fill up the night before. Power does the same. Twice a weekday.
We’re in the high-demand season now: June, July, August. That’s the bill in front of you.
A unit drawn in a peak block costs 720.19 c/kWh.
The same unit drawn overnight costs 120.03 c/kWh.
Both exclude VAT. Same tariff. Same supply point.
720.19 ÷ 120.03 = 6.0
You pay six times the price for the same unit. The only thing that changed is the hour you drew it.
The Winter Window Is Worth About R6 a Unit
720.19 − 120.03 = 600.16 c/kWh excl VAT.
That’s roughly R6 of value for every unit you move from a peak block to an off-peak one. Not save. Move.
In summer the same window is 298.89 − 120.03 = 178.86 c/kWh. Still worth having. Not the same animal.
Ruraflex is wider again. Winter peak is 732.98 c/kWh against 122.16 off-peak. A spread of 610.82 c/kWh, the widest window in the schedule. Agri-processors and packhouses feel this hardest.
One caveat. On Ruraflex the network demand charge is 45.56 c/kWh, charged in every period. It’s an energy charge wearing a demand charge’s name. Shifting load doesn’t touch it. Using less does.
On Nightsave Urban the Lever Is kVA, Not kWh
Think of water. Energy is the litres you drew this month. Demand is how wide the pipe had to be at your thirstiest moment. You pay for both.
Litres are kWh. Pipe width is kVA.
Nightsave Urban (Large) is Megaflex’s mirror image. Its energy charge barely moves with the season: 177.20 c/kWh in winter, 170.21 in summer. It isn’t time-of-use.
The whole tariff hangs on one line. The energy demand charge.
- High season (Jun–Aug): R332.91/kVA/month.
- Low season (Sep–May): R77.88/kVA/month.
That’s a 4.3× swing for the same peak. R255.03/kVA/month more in winter than in summer.
Peak shaving attacks that line. Put a battery between your load and the meter. It works like a dam wall. Your surge never reaches the meter.
Shave one kVA off your peak and two charges fall. The energy demand charge, and the distribution network demand charge of R26.29/kVA/month.
- Winter: R332.91 + R26.29 = R359.20/kVA/month excl VAT.
- Summer: R77.88 + R26.29 = R104.17/kVA/month excl VAT.
- Per 100 kVA shaved: R35,920/month in winter, R10,417/month in summer.
- Annualised, 3 winter months + 9 summer months: (3 × R35,920) + (9 × R10,417) = R201,513/year excl VAT per 100 kVA.
R35,920 a month is a delivery vehicle payment. For pipe width you use a few minutes a day.
That sum is behind every serious peak-shaving business case I build. It’s also why a battery sized on January data disappoints in July.
Which Levers Don’t Move — and Who Has None
The Megaflex distribution network capacity charge is R39.13/kVA/month. It is billed on annual utilised capacity: your highest demand across the whole year, not this month’s. So it does not fall the month after you shave a peak.
Some models multiply every R/kVA charge by the kVA you plan to shave. That model overstates your saving.
Then there’s Businessrate. None of the demand-charge argument applies there.
Businessrate covers urban supplies up to 100 kVA with no grid-tied generation. It has no R/kVA/month demand charge at all. Its network demand charge is 15.81 c/kWh, an energy charge.
There is nothing to shave. If you’ve been quoted a peak-shaving battery on a Businessrate supply, ask which line on the bill it reduces.
Knowing which line your capex attacks is most of the engineering. The rest is sizing.
Worked Example: Moving 800 kWh a Day on Megaflex
Every assumption on the table.
Assumptions. These are Terawatt modelling inputs, not published facts:
- Megaflex, non-local-authority, ≤300 km, ≥500 V and <66 kV. Rates excl VAT, from the 2026/27 Schedule.
- The system delivers 800 kWh into peak periods per weekday. That’s roughly 200 kW for about two hours, in each of the two weekday peak blocks. It implies a battery of about 200 kW power and 900 kWh usable energy.
- Round-trip efficiency of 90%. That’s how much of what you put in comes back out. An engineering assumption, not a spec sheet number.
- Recharge happens in off-peak, at 120.03 c/kWh.
- 22 weekdays per month, no shutdown weeks.
- Shifted energy only. No demand-charge saving counted, no solar, no diesel.
The working:
- To deliver 1 kWh in peak you must buy 1 ÷ 0.90 = 1.111 kWh off-peak, at 120.03 c/kWh → 133.37 c.
- Winter net value: 720.19 − 133.37 = 586.82 c/kWh delivered (R5.87).
- Summer net value: 298.89 − 133.37 = 165.52 c/kWh delivered (R1.66).
- Winter volume: 3 months × 22 days × 800 kWh = 52,800 kWh → 52,800 × R5.8682 = R309,841.
- Summer volume: 9 months × 22 days × 800 kWh = 158,400 kWh → 158,400 × R1.6552 = R262,184.
- Annual avoided cost: ≈ R572,000 excl VAT.
Now look at the shape of it. R309,841 of that R572,000 sits in three months. That’s 54% of the annual value inside one quarter.
Commission in September and you’ve missed more than half of year one.
There’s no capex figure here, and no payback in months. Battery pricing moves with the rand and with cell prices. A number I write today is stale by October.
What you have is the avoided cost and the sums behind it. Get your site costed, then divide. The savings calculator gets you close, and our comparison of 1 MWh and 500 kWh systems covers sizing.
Why Next April Matters More Than This One
NERSA got Eskom’s regulatory asset base wrong by R54.7 billion.
A High Court order forced public consultation. The regulator then settled on clawing the error back through tariffs, over three years:
- R12 billion in 2026/27.
- R23 billion in 2027/28.
- R19.7 billion in the period after that.
Strip that clawback out and this year’s increases would have been 5.36% for Eskom-direct customers and 6.19% for municipalities. The approved numbers were 8.76% and 9.01%.
Read that sequence again. What you’re paying now is the small instalment.
So anyone modelling a solar or storage payback on today’s tariff is being cautious, not hopeful. That’s an odd place to be. It won’t last.
Eskom-Direct or Municipal? Check Which You Are
Megaflex, Nightsave Urban, Ruraflex and Businessrate are Eskom-direct tariffs. They moved on 1 April.
Supplied by Johannesburg, Cape Town or eThekwini? You’re on that city’s tariff. Those increases landed on 1 July. eThekwini went up 9%, cut back from a proposed 10.5%.
So in a metro, the rates above are not yours. The structure usually is. Our tariff and load shedding forecast covers what’s next.
What to Do This Week
The first three steps cost nothing.
- Find your tariff name on the bill. Then find the split: peak, standard and off-peak units, or the R/kVA/month line.
- Check Appendix A, Figure 2 of the Schedule for your peak windows. They shift by season.
- Split your demand charges in two. Those billed on this month’s peak, and those on the year’s peak. Only the first kind responds to shaving.
- Then, and only then, get equipment priced.
Most owners have a view on whether the tariff is fair.
Almost none can tell me their spread. Or which demand charge falls when they shave. Or how much of their year sits in winter.
You can’t change the price. You can change which price you pay.
The spread is published. It’s 6:1 right now. About five weeks of it are left this year.
FAQ
Which Eskom tariff has the widest peak to off-peak spread?
Ruraflex. In the high-demand season its peak energy charge is 732.98 c/kWh against 122.16 off-peak. That’s a spread of 610.82 c/kWh excl VAT. Megaflex is close behind at 600.16 c/kWh. Both shrink in summer.
Does peak shaving reduce every demand charge on my bill?
No. On Megaflex the distribution network demand charge of R26.29/kVA/month is billed on this month’s peak, so it falls. The capacity charge of R39.13/kVA/month is billed on the year’s peak, so it doesn’t. A model treating them alike overstates your saving.
My municipality bills me, not Eskom. Does this apply?
The rates don’t. Those are Eskom-direct tariffs, and your increase landed on 1 July, not 1 April. But most metros run time-of-use and demand-based structures for larger users. Get your own schedule and find the matching lines first.
Should I wait for the next increase before running the numbers?
No. The R54.7bn clawback roughly doubles next year, so a payback built on today’s tariff is already cautious. Waiting doesn’t improve your answer. It costs you a winter. Engineering and grid approvals also start well before next June.
Will a battery help if I’m on Businessrate?
Not for demand charges. Businessrate covers urban supplies up to 100 kVA with no grid-tied generation. It carries no R/kVA/month demand charge. Its network demand charge is 15.81 c/kWh, an energy charge. There is no demand line for a battery to cut.
Find out which levers your bill has.
Send us twelve months of bills, plus half-hourly data if you have it. We’ll name your tariff, then split the charges that respond to load-shifting from the ones that don’t. You get a number on your winter exposure. No obligation. If you shouldn’t spend, we’ll say so.
All tariff figures are taken from Eskom’s Schedule of Standard Prices 2026/27, effective 1 April 2026, for non-local-authority supply in the ≤300 km transmission zone at ≥500 V and <66 kV, and exclude VAT unless stated. Rates vary by voltage, distance and supply category — check your own schedule. Nothing here is financial or tax advice.
