Eskom Data Portal · Actual Generation · May 2025 – May 2026
Open Cycle Gas Turbine (OCGT) Generation
Eskom OCGT + Dispatchable IPP OCGT · Hourly actual dispatch · Last 12 months
1,567 GWhTotal OCGT energy generated (Eskom + IPP, 12 months)
462 GWhEskom OCGT only (30% of total)
1,105 GWhIPP OCGT (70% of total)
3,058 MWPeak combined dispatch 7 Jul 2025, 20:00
0.74%Avg OCGT as % of residual demand (12m)
Key finding: Eskom OCGT was dispatched heavily in May–Jul 2025 (winter onset, 397 GWh across 3 months) then almost completely stood down from August 2025 onwards — dropping to near-zero from Aug 2025 through Feb 2026. IPP OCGT ran continuously throughout at a near-constant ~100 MW baseload, suggesting a contracted minimum dispatch obligation. Eskom OCGT has resumed modest dispatch from March 2026 as winter approaches again.
Data: Eskom Data Portal historical download (Apr 2022–May 2026) · OCGT columns: “Eskom OCGT Generation” and “Dispatchable IPP OCGT” · Each row represents one hourly interval · MW values are average sent-out generation for that hour · GWh calculated as sum of hourly MW / 1000
Flattening the Curve — What Every Solar Installer Needs to Know
Technical Guidance · Solar PV Installers
You Installed the Panels. Now Flatten the Curve.
South Africa’s grid load profile reveals a clear daily pattern of stress and relief.
This article describes that problem — and one approach to addressing it.
The principles are universal. The execution will vary by site, inverter platform, and client.
Based on Eskom Actual Residual Demand data · Apr 2022 – May 2026 · Weekday averages
29.3 GWWinter evening peak demand (18:00 average)
3.6 GWSeasonal peak gap winter vs. summer
~5 GWEmbedded rooftop solar installed nationally
What the Load Curve Is Telling Us
The interactive chart below is not just a technical diagram. It is a map of exactly when South Africa’s
electricity infrastructure is under stress — and by extension, when every poorly configured solar system
on the grid is making things worse rather than better.
Two features of the curve demand attention from anyone who installs rooftop solar and battery systems.
Use the controls to toggle between seasons and explore how the TOU tariff bands align with the actual
demand peaks.
Interactive · Eskom National Grid Load Profile · Actual Residual Demand · Apr 2022 – May 2026
Eskom Data Portal · Actual Residual Demand · Weekday averages
Look at the chart above and three things stand out immediately. First, a sharp morning spike
from around 05:00 as the country wakes up — strongest in winter when heating loads stack on
top of the usual morning routine. Second, a midday trough visible in the summer curve between
11:00 and 15:00, the fingerprint of embedded rooftop solar now suppressing grid draw during
peak generation hours. Third, the most severe feature of all: the evening peak, where demand
climbs hard from 16:00 and hits 29.3 GW at 18:00 in winter — at the exact
moment solar generation reaches zero.
These three features define the grid’s daily stress pattern. They are as consistent as the
sunrise. And they are precisely what a correctly configured battery system should be designed
to address.
The Problem: What Most Systems Actually Do
Before describing a possible solution, it is worth being precise about what the problem
actually is — because it is not the hardware. The panels, inverters, and batteries installed
across South Africa are largely capable of far more intelligent behaviour than they are
currently delivering. The problem is the default dispatch pattern that most systems follow
after installation, and the absence of any deliberate strategy to change it.
The dominant pattern among installed solar-plus-battery systems follows a simple and deeply
inadequate cycle:
The Common (Wrong) Dispatch Pattern
Battery discharges after sunset through the evening. Once depleted, the system draws from
the grid through the night and into the morning. Solar charges the battery back up during
the day. Battery reaches 100% by mid-morning and then sits there — fully charged, doing
nothing — until the sun goes down again. Repeat.
On paper this looks reasonable. In practice it means the battery is idle at 100% through the
midday period when it should be absorbing surplus solar generation — and it means the morning
peak, one of the two hardest periods for the grid, is covered entirely by Eskom because the
battery exhausted itself the previous evening and solar hasn’t recovered it yet.
The battery is cycling once per day, serving one peak, and sitting unused through most of the
period when it could be most useful. This is not a grid asset. It is a glorified UPS.
A Possible Solution: The Full-Day Dispatch Model
What follows is one approach to addressing the problem described above. It is not the only
approach, and its execution will depend on the inverter platform, battery capacity, site
load profile, and the client’s priorities. The underlying principles, however, are consistent:
the battery should be cycling in response to the grid’s actual daily stress pattern, not
simply reacting to sunset and sunrise.
The model described here targets two discharge events per day — one at the
morning peak, one at the evening peak — with two corresponding recharge events: a slow
overnight grid charge during the off-peak trough, and a solar midday charge during peak
generation hours. The target state of charge before each discharge is 95%,
with a 40% floor maintained as an emergency reserve that is never drawn into
under normal operation.
On a 10 kWh battery, the usable window of 95% to 40% gives 5.5 kWh per discharge event —
11 kWh of active daily contribution across both events. The specific numbers will differ by
system size and load profile. The principle does not.
The 24-Hour Dispatch Cycle
22:00 – 06:00
🔋
Slow grid charge to 95% SoC
Off-peak period — lowest grid demand of the day. Slow charge rate to avoid adding load spike. System draws steadily through the night.
06:00 – 08:00
⚡
Discharge — morning peak cover
Battery discharges to cover morning loads. No grid draw. Floor: 40% SoC emergency reserve. Grid demand climbs sharply here — the battery absorbs it.
08:00 – 10:00
☀️
Solar ramps up, covers daytime loads
Solar takes over household consumption. Battery at ~40–50% resting. Grid demand is declining — no battery action needed.
10:00 – 15:00
🔋
Solar charges battery back to 95%
Peak generation window. Priority: serve loads → charge battery → export surplus only. Target 95% SoC by 15:00. This is the midday recharge that makes the second daily discharge possible.
Deferred PV charging: Do not start battery charging from solar at first light — allow morning solar (08:00–10:00) to serve loads directly while the battery rests at 40%. Defer bulk PV charging to the midday window when generation is at its strongest. This intentionally deepens the midday demand dip on the grid curve, maximising the embedded solar benefit at exactly the point it is most visible. The battery charges faster and more efficiently at peak irradiance, and the grid sees a more pronounced suppression during the 10:00–15:00 window.
15:00 – 17:00
☀️
Solar covers loads, battery holds at 95%
Battery fully charged and waiting. Solar still generating. Grid demand beginning to climb. Hold battery in reserve for the peak ahead.
17:00 – 20:00
⚡
Discharge — evening peak cover
The critical window. Battery discharges to cover all loads. Zero grid draw. Floor: 40% emergency reserve. This is where the national grid hits 29+ GW — every kWh discharged here is one less Eskom must generate.
20:00 – 22:00
🌙
Grid covers remaining evening loads
Battery at 40% reserve. Grid demand easing. System draws lightly from grid. At 22:00 the overnight charge cycle begins again.
On Overnight Grid Charging
Overnight grid charging is likely the most counterintuitive element of this approach —
and the one most likely to need explanation to both clients and fellow installers.
The principle behind it is worth understanding clearly, because the justification is
not primarily financial.
Between 22:00 and 06:00, national demand drops to its daily low — around 19–21 GW. Generation
capacity is in surplus. Coal stations that cannot be ramped down are running at minimum load.
Pulling a slow, steady charge from the grid at this hour adds almost no marginal stress —
it is absorbing capacity that would otherwise go to waste.
Compare that to the morning peak at 07:00, when demand climbs toward 26 GW and every available
generation unit is running hard. A battery that is still recovering from the previous evening —
drawing from the grid at this moment to recharge — is adding load at exactly the wrong time.
The overnight charge eliminates this entirely.
This Is Not About Cost — It Is About When
The motivation for overnight grid charging is not primarily financial, though on TOU tariffs
the off-peak rate saving is a genuine client benefit. The motivation is grid timing. Charging
slowly through the night at low-demand hours, and discharging at the two daily peaks, is
what active grid participation looks like. A battery configured this way is doing something
useful 24 hours a day — not just for four hours after sunset.
On flat-rate and IBT installations, overnight charging costs the same per kWh as any other
time. There is no financial penalty for the client. The grid benefit is identical. The case
for doing it is purely about responsible system configuration.
The 40% Floor — Always Hold the Reserve
The 40% state of charge floor is not a soft guideline. It is a hard limit that should be
programmed into the inverter’s depth-of-discharge setting and never overridden.
It serves two functions. The first is practical: it preserves genuine emergency capacity.
An unplanned grid outage at 19:30, a client’s medical equipment, a power cut that runs
longer than expected — the 40% reserve is what covers those events without the system
being caught empty. The second is technical: consistent deep discharge below 40% accelerates
battery degradation, particularly in lithium iron phosphate chemistry. Holding the floor
protects the battery investment and maintains usable capacity over its service life.
The usable window — 95% to 40% — represents 55% of nominal capacity per
discharge event. On a 10 kWh battery that is 5.5 kWh. On a 15 kWh system, 8.25 kWh.
Twice daily that is a meaningful and consistent contribution. Do not be tempted to squeeze
the floor lower to extend evening coverage — size the battery correctly instead.
This Applies to Every Installation
The full-day dispatch model described above applies equally to TOU-billed clients and to those
on flat-rate or inclined block tariffs. The grid does not differentiate. The morning peak at
07:00 is just as real for a client paying a flat rate per kWh as for one on Megaflex (TOU). The battery’s
state of charge at that moment has the same effect on grid stress regardless of the bill.
TOU billing provides a financial signal that reinforces good behaviour — cheaper overnight
charging, more expensive peak-hour grid draw — but the underlying configuration logic is
identical. An installer who only applies active dispatch management to TOU clients is doing
a disservice to the majority of their installed base and to the grid they all share.
“The load curve is your configuration brief. It tells you exactly when the grid needs
help. Your client’s tariff structure does not change that — it only changes whether
the client notices the benefit on their electricity bill.”
Principles for Implementation
The following points describe what a system configured along these lines should achieve,
and the considerations relevant to each phase of the daily cycle. How each is implemented
will depend on the inverter platform and its scheduling capabilities — the intent here
is to describe the desired outcome and the reasoning behind it, not to prescribe
specific menu paths or parameter values.
The intent is to enter the morning peak with a full battery, charged during the
period of lowest national demand. The charge rate should be spread across the available
window rather than concentrated at the start — a slow, steady draw is what makes this
benign to the grid. On most platforms this means setting a charge current that would
fill an empty battery over six to eight hours, not two. The specific current value
depends on battery capacity and inverter capability.
2
Morning Discharge — Battery as Primary Source, 40% Floor
During the morning peak the battery should be the primary source, with grid draw
minimised or eliminated until either the 40% floor is reached or solar generation
takes over. The 40% floor should ideally be enforced at the inverter firmware level
rather than purely as a schedule parameter — this ensures the floor is respected
regardless of what the schedule is doing. On most winter mornings solar will not be
generating meaningfully until well after the peak begins, so the battery carries
the full load for this period.
3
Midday Solar Charge — Battery Before Export, Deferred Start
During peak solar hours the charge priority should be: serve loads → charge
battery to 95% → export only the genuine surplus. This is the setting that enables
the second daily discharge event — without it, the battery arrives at the evening
peak partially charged. Most factory defaults favour export over charging; this
behaviour should be explicitly reviewed and changed where necessary.
The solar charge should be deferred — not
started at first light. Between early morning and approximately 10:00, solar should
serve loads directly while the battery rests at its morning floor. Starting the bulk
charge when irradiance is approaching its daily peak means faster charging, better
panel efficiency, and — across the installed base — a more pronounced midday demand
dip on the national grid curve. How this deferral is implemented depends on the
inverter platform: some support a self-consumption period type that achieves it
natively; others require a charge current limit or a scheduled block.
4
Evening Discharge — Battery as Primary Source Through the Peak
The evening peak is the critical window — the highest national demand period of
the day. The battery should be the sole source through this period, with grid draw
suppressed and export disabled. The same 40% floor applies. In winter this window
runs broadly from 17:00 to 20:00; in summer the peak shifts later, broadly 18:00
to 21:00. Both seasonal variants should be considered at commissioning and documented
clearly. If battery capacity is insufficient to maintain the floor through a typical
winter evening peak, that is a design conversation, not a configuration adjustment.
5
Geyser and Large Loads — Out of Both Peak Windows
The geyser is typically the largest controllable load on a residential installation.
Running it inside either peak discharge window forces the battery to cover it at the
expense of other loads, or draws from the grid at the worst possible moment. Scheduling
it during solar midday or deep overnight off-peak removes it from the battery’s discharge
burden entirely. The same principle applies to any other large schedulable load —
pool pumps, underfloor heating, EV charging. The specific scheduling method will depend
on what controllable switching is available on site.
6
Seasonal Variation — Summer and Winter Profiles Differ
As the load curve makes clear, the summer and winter demand profiles are meaningfully
different in shape and timing. Evening peak starts earlier in winter, morning peak is
sharper, and solar generation windows are shorter. A system configured for summer
conditions will not behave optimally through winter. Whatever approach is used,
the seasonal difference should be considered — whether through dual seasonal
configurations, a scheduled review, or a platform that adapts automatically.
The Bigger Picture
South Africa has approximately 5 GW of embedded rooftop solar installed,
growing by over 1 GW per year. The midday dip now visible in the national load curve is
direct evidence that the installed base is having a measurable effect on grid demand.
That is a meaningful achievement.
But the morning and evening peaks — the two moments of greatest daily grid stress — remain
almost entirely served by Eskom’s conventional generation fleet. At 18:00 on a winter
weekday, the grid is carrying 29+ GW. The sun is down. Solar contributes nothing. At 07:00
the following morning, demand is surging toward 26 GW and most battery systems are still
recovering from the night.
The hardware to change this is already installed on rooftops across the country. The potential
is tens of gigawatt-hours of active daily dispatch capacity sitting in residential batteries,
cycling once a day at best, configured to serve the client’s convenience rather than the
grid’s need.
The gap is not hardware. It is not cost. It is configuration knowledge and the professional
standard to apply it on every job. That is entirely within the control of the installer.
What Flattening the Curve Actually Means
A flatter load curve means less strain on generation and transmission infrastructure,
fewer emergency generation events, a more stable grid frequency, and a lower average
cost of electricity production for everyone. For your clients it means genuine energy
independence at the moments that matter — morning and evening, every day, not just
during load shedding. For the industry it means installations that can be pointed to
as a demonstrated contribution to grid stability rather than a rooftop accessory
that happens to reduce one person’s electricity bill.
Summary of Principles — Not a Prescriptive Checklist
The following summarises the intent behind each phase of the dispatch approach described
above. How each is achieved depends on the inverter platform, site conditions, and
available controls. The goal in each case is clearly stated; the method is for the
installer to determine.
◎ Overnight: charge battery to ~95% using slow grid draw during low-demand hours
◎ Morning peak: battery as primary source; minimise grid draw; hold 40% reserve
◎ Early solar: serve loads from PV directly; defer bulk battery charging
◎ Midday solar: charge battery to ~95% before exporting surplus
◎ Pre-evening: battery fully charged and held in reserve
◎ Evening peak: battery as primary source; suppress grid draw; hold 40% reserve
◎ Large loads (geyser, pool): scheduled outside both peak discharge windows
◎ Seasonal difference: addressed — whether through dual configs or platform adaptation
◎ All of the above regardless of tariff structure
The panels are the easy part. Anyone can put panels on a roof. The value you add as an
installer is in the intelligence of what sits behind them — a dispatch strategy that puts
stored energy into the grid at the moments of greatest need, twice a day, every day,
summer and winter.
A battery configured for active full-day dispatch is doing its job. Everything else is
leaving the work half done.
Loadshedding has become South Africa’s Number One ‘Sport’ as various Ministers and a parade of CEO’s peddle the latest quick fix solution.
Many of us cannot afford a decent Solar System to keep the lights on and have developed our own coping mechanisms to make loadshedding just that tiny bit more palatable.
Here are 15 tips to help you survive load shedding risks, without the need of a generator or solar panels:
Know your schedule: Make sure that you keep track of any scheduled outages in your area by downloading a reputable Eskom load shedding app on your smartphone. Alternatively, ask to be added to a group of friends who can keep one another updated on planned load shedding schedules.
Be security savvy: The sad reality is that criminals also study load shedding schedules to identify which areas will be vulnerable at specific times. Tripped and false alarms are great opportunities for opportunistic burglars. Be extra vigilant about access to your home and securing your perimeter.
Get back-up batteries for your alarm and gate system: Ensure that your alarm system is in a working condition and the back-up battery is fully functional to provide power to the system in the event of load shedding. Similarly, check that your garage door motor or electronic gate can function without power.
Make sure you have sufficient back-up lighting: Keep a torch or headlamp in your car if you arrive home at night during a power outage. Most smartphones have built-in torches or torch apps which come in handy during unexpected power outages – which bring us to the next point…
Always stay charged: Ensure your cellphone, laptop and tablet devices are fully charged ahead of scheduled blackouts. Be sure to charge them again as soon as possible after the power returns. It’s also a good idea to have an emergency phone charger and power bank close by. This comes in handy during extended power outages.
Plan to stay connected: Staying connected to the internet is a great way to keep in touch with what’s happening as well as for regular updates, so ensure that your mobile data stays topped up. Remember to use devices sparingly during outages so that you don’t drain the battery completely before the power returns.
Don’t forget the benefits of gas: Invest in a small gas bottle and lamp to for cooking and lighting. A gas lamp provides good quality lighting for a large area and a gas cooker can be a life saver during electricity cuts. It’s a good idea to keep hot water in a thermal flask so that you can make hot drinks. Prepare meals beforehand if you know there’s going to be a scheduled blackout during meal times.
Stock up on bottled water and pop some in the freezer: Some households depend on electric pumps for their water supply, especially in rural areas. Frozen bottled water will help keep food cold during a power outage and will also not spoil. Having a few extra bottles handy will ensure you won’t run out during outages.
Keep the cold in: Leave your freezer and refrigerator doors closed as much as possible to preserve the temperatures inside. Did you know that a fully stocked freezer should keep food safe for up to two days and a refrigerator for four to six hours?
Unplug your cables as soon as the power goes out: Consider any electrical connection as live during a power outage as power can return at any time. Unplug any electronic devices or equipment or switch it off at the wall, including fixed telephone cables. This will help prevent damage or injury due to surges that may occur when electricity is restored.
Back up your data: If you save important data on our home computer, consider backing it up over the internet in case of a hard drive crash or unforeseen electrical fault. Online cloud-based backups are very convenient and are mostly automated, which means that you have one less thing to worry about.
Know your emergency contacts: Save emergency contact information on your phone but also keep a printed copy close by. This should include emergency services such as the fire department, police and medical services. Also include contact information of friends and family along with your insurance information.
Buy perishables in smaller amounts: With longer and more frequent blackouts, perishables like vegetables are more likely to spoil. So, shop sparingly. While your fridge/freezer can preserve food for a few hours without power, the higher stages may not give the system enough time to reach optimal temperatures. While we often advise buying in bulk to save, in this case, less is definitely more.
Plan tasks around the schedule: Cook when you can so you don’t spend money on takeaways or going out. Time your laundry so you don’t end up with a half-washed load that needs to be rewashed when the power comes back. All these little expenses add up.
Gather the family together: Instead of having each family member squirrelled away in their own room, gather everyone together. You’ll be using fewer lights and spending more quality time together.
Electric surges are one of the biggest causes of damage to your household equipment during a power outage. Installing a surge protection device can help minimise some damage in unforeseen situations. Have a surge protection device fitted to your electrical distribution board or at the power outlets to electronic devices. Contact a profession electrical contractor to discuss the process and costs involved.
Saving electricity leads to longer lasting appliances and less load on your electrical installation. In the long run this will save you lots of money. Eskom has shared these tips that every household can use to save energy and money:
Geysers
1. Set your electrical geyser’s thermostat at 55 ° C to 60 ° C. To save energy, make sure the geyser and all hot water steel pipes in the roof are well insulated with fibreglass or newspaper.
2. Solar heating units could reduce the geyser’s electricity consumption by 40% to 50%. This would result in a savings of about 200kWh to 250kWh of electricity per month, depending on the number of geysers and the size of the family.
Lights
3. Switch off the lights when they are not needed.
4. Use fewer bulbs with higher wattages. For instance, one 100 watt bulb produces the same light as two 60 watt bulbs.
Use the correct heaters. Infrared electricity heaters are the most energy efficient heaters available while oil heaters are the safest.
6. Use compact fluorescent lamps (CFL) instead of ordinary bulbs.
7. Use low-energy lamps for exterior lighting.
Heating
8. Use the correct heaters. Infrared electricity heaters are the most energy efficient heaters available while oil heaters are the safest.
9. Insulate the ceiling and seal air gaps in the home.
10. Ensure that heaters have thermostats.
11. Use electric blankets but turn them off when in bed.
Dishwasher
12. Fill the dishwasher completely before operating it.
13. Turn off the dishwasher before the drying cycle so that you can wipe the dishes clean with a dry cloth.
14. Connect the dishwasher to the cold water supply.
15. Clean filters.
16 When buying a dishwasher, look for energy saving features like a short wash cycle.
Install your dishwasher away from your refrigerator. The dishwasher’s heat and moisture make the refrigerator work harder.
17. Install your dishwasher away from your refrigerator. The dishwasher’s heat and moisture make the refrigerator work harder.
Tumble Dryers
18. Tumble dryers that operate with an electronic humidity control are the most efficient as they automatically shut off the drying cycle when clothes are dry.
19. Use correct temperature settings to minimise the amount of electricity used.
20. Remove water before putting clothes into the tumble dryer.
21. On sunny days, take the opportunity to dry your clothes outside.
Automatic washing machines
22. A front loading washing machine uses less water and costs less to operate.
232. Use the warm water setting to cut down on electricity needed to heat the water.
24. Make sure you have a full load before washing.
25. Select the shortest possible washing programme.
Keep oven doors closed until food is cooked.
26. Cold water detergents reduce electricity consumption.
Stoves
27. Use pressure cookers when preparing food that takes a long time to cook.
28. Match pots and pans to stove plates. Small pots on large plates waste electricity.
29. Do not use pots with distorted bottoms.
30. Switch off the plates or oven before food is fully cooked. This allows you to finish your cooking without using energy.
31. Keep oven doors closed until food is cooked.
32. Do not preheat the oven. It isn’t necessary to preheat the oven except for food requiring high temperatures and slow cooking times.
33. Make use of the oven’s leftover heat. Your oven retains heat for 15 to 30 minutes after it is turned off. Use that free heat to warm up desserts, rolls or freshen crackers and cookies.
34. Glass and ceramic pans retain heat better than metal pans.
Don’t open the fridge door unnecessarily and make sure the seal is intact.
35. Use the self-cleaning feature only when it’s necessary. Start the self-cleaning cycle right after cooking while the oven is still hot. Less energy will be required to reach cleaning temperature.
Microwave Ovens
36. When you defrost food, leave it in the fridge overnight. You’ll use less electricity than defrosting food in the microwave.
37. Use the microwave to cook small to medium quantities of food. For larger portions of meat, it’s better to use a conventional oven or pressure cooker.
Refrigerator
38. Don’t open the door unnecessarily and make sure the seal is intact.
39. Turn off an empty refrigerator when going on holiday.
40. Let hot foods cool down before placing them in the refrigerator.
41. Defrost fridges regularly. A build-up of ice reduces operating efficiency and increases running costs.
Freezers
42. Defrost the freezer regularly. Freezers work harder to remove heat and have to use more power. Only 90% of a freezer’s capacity should be used for freezing.
General
43. Do not buy larger or more powerful appliances than are actually required.
44. Do not buy an electric appliance when a hand-operated one will suffice.
45. Use the correct appliance for the job e.g. do not make toast on the stove or in the oven.
46. Do not fill a kettle if only a small quantity of boiling water is required. It is sufficient to put in only enough water to cover the element.
47. It is more economical to boil water in a kettle rather than in a pot on the stove.
48. Always use an iron that is thermostatically controlled. You can avoid ironing clothes by removing clothing promptly from tumble dryer and folding them carefully.
49. Operate swimming pool filter pumps for minimum periods.
50. Paint the walls of your home in a light colour. Dark colours tend to absorb light, requiring you to use more energy from light bulbs to achieve the same effect.
