GUsually the largest single load
Geyser
Heating schedule, water use and element size.
Heating scheduleWater useElement size
Home Energy AssessmentResidential
A more cost-effective home
Measure your electricity use, reduce waste and make better use of solar energy.
Designed around your home and your bill.
Measured, not guessed
CT monitoring on the main supply and selected circuits
Eskom · 1 Apr 20268.76% increase
Tshwane · 1 Jul 20268.8% increase
10
Annual increases
in the ten completed years to 2025/26
8.76%
Eskom increase
effective 1 April 2026
8.8%
Tshwane increase
effective 1 July 2026
Why now
Electricity prices have increased every year
Homeowners can reduce exposure by lowering the number of grid units they need.
Eskom average tariff increase
Percent per financial year, 2016/17 to 2026/27
Ten-year average 9.33%Current year
9.40%
2.20%
5.23%
9.41%
8.10%
5.22%
9.61%
18.65%
12.74%
12.74%
8.76%
16/1717/1818/1919/2020/2121/2222/2323/2424/2525/2626/27
Compounded over eleven increases
Electricity that cost R100 in 2015/16 costs about R263 once the 2026/27 increase applies. Annual increases compound — they do not add up.
+163%
2016/17 → 2026/27
Eskom average tariff increases provide a national reference. Municipal retail tariffs, including Tshwane, differ by tariff structure.
View the data and sources
| Financial year | Average increase |
|---|---|
| 2016/17 | 9.40% |
| 2017/18 | 2.20% |
| 2018/19 | 5.23% |
| 2019/20 | 9.41% |
| 2020/21 | 8.10% |
| 2021/22 | 5.22% |
| 2022/23 | 9.61% |
| 2023/24 | 18.65% |
| 2024/25 | 12.74% |
| 2025/26 | 12.74% |
| 2026/27 | 8.76% |
Sources: Eskom Distribution tariff books and tariff history; Statistics South Africa, Municipal finances and electricity: 11 years in perspective; NERSA decisions. Values are average Eskom increases, not a City of Tshwane residential retail price series.
The +163% headline is the compounded product of all eleven increases (1.094 × 1.022 × … × 1.0876 = 2.63), not their sum. It describes the Eskom average tariff — the price per unit — not a household’s consumption.
City of TshwaneApproved
8.8%
Average electricity tariff increase, effective 1 July 2026.
Next approved Eskom increaseScheduled
8.83%
Effective 1 April 2027 for Eskom. Tshwane's July 2027 retail tariff still requires municipal and regulatory approval.
The saving opportunity grows as grid electricity becomes more expensive, but every recommendation must use the homeowner’s actual tariff.
Where it goes
Where a home uses electricity
ISI separates fixed loads, timed loads and lifestyle-dependent loads before recommending equipment.
Pool pump
Pump size, filtration hours and season.
Cooling and heating
Air conditioning and underfloor heating.
Kitchen
Oven, hob, kettle and refrigeration.
Lighting
Fitting wattage and operating hours.
Standby loads
Devices drawing power when nobody uses them.
A CT measurement confirms which loads deserve attention in your specific home.
The assessment
The assessment starts with evidence
Bills show the total cost. CT monitoring shows which appliances and time periods created it.
- 01
Collect
Electricity bills, tariff, inverter data and household schedule.
- 02
Measure
Main supply and selected circuits using CT monitoring.
- 03
Analyse
Daily profile, solar production, battery behaviour and avoidable grid use.
- 04
Propose
Prioritised solutions with estimated savings and a formal quotation.
The assessment can include temporary monitoring or permanent energy meters, depending on the required detail.
Staged plan
A staged plan controls cost and risk
Start with the strongest measured opportunity, then expand when the data supports the next investment.
1
Control
Schedules, temperatures and unnecessary base load.
2
Water heating
GeyserWise control or dedicated PV water heating.
3
Solar and battery
Size panels, inverter and storage for the measured profile.
4
Optimise
Reconfigure an existing system to use more of its own solar.
Homeowners can implement one stage or combine them in a single project.
Water heating
Water heating can move away from the grid
A GeyserWise solution can control heating times or use dedicated solar PV to heat the existing cylinder.
PV panels
Dedicated DC energy
MWS controller
MPPT controls power to the element
Existing geyser
Stores hot water for later use
AC backupGrid heating only when required
Manufacturer specification. The MWS manufacturer specifies a 120 to 350 VDC MPPT operating range, panel current below 15 A and at least three suitable panels in series.
Engineering checks
- Element resistance and rating
- PV voltage and current
- Cylinder size and water demand
- Roof orientation and shading
- Electrical protection and compliance
Solar priority
Solar energy should follow the home’s priorities
A well-configured system uses daytime production where it creates the most household value.
- 1
Live house loads
Use solar directly while it is available.
- 2
Battery
Store energy for evening use and outages.
- 3
Smart loads
Heat water, run the pool or other flexible loads.
- 4
Grid or export
Use or export only within the approved design and tariff.
This is priority order, not quantity. The order can change to suit the homeowner’s tariff, backup requirement and lifestyle.
Existing systems
Existing inverter systems often need better settings
The goal is to reduce avoidable grid use while protecting battery life and backup capacity.
- Solar self-use
- Supply daytime loads directly from PV.
- Battery reserve
- Keep enough state of charge for outages.
- Smart schedules
- Move geyser and pool loads into solar hours.
- Grid charging
- Disable or limit it unless the tariff or backup plan justifies it.
- Peak periods
- Use batteries strategically only when the tariff rewards time shifting.
- Surplus solar
- Feed flexible household loads before curtailing production.
On a flat or block tariff, charging a battery from the grid and discharging it later normally adds losses instead of saving money.
Illustrative example
Illustrative household opportunity
The real proposal will use measured consumption, the current tariff and the selected equipment.
Example baseline · 1,000 kWh grid electricity per month
250 kWh
450 kWh
300 kWh
- Geyser improvement · 250 kWh
- Solar and battery use · 450 kWh
- Remaining grid use · 300 kWh
70%
lower grid energy in this example
Illustrative exampleView the figures behind this example
| Component | kWh per month | Share of baseline |
|---|---|---|
| Geyser improvement | 250 | 25% |
| Solar and battery use | 450 | 45% |
| Remaining grid use | 300 | 30% |
| Baseline | 1,000 | 100% |
Source: ISI Home Energy Optimisation proposal. The 70% figure is the geyser improvement and the solar and battery contribution together (250 + 450 = 700kWh) as a share of the 1,000 kWh baseline. The baseline is a round illustrative number chosen for the deck, not a measured household.
Deliverables
What the homeowner receives
ISI converts measurements into a practical scope and quotation.
Home Energy Assessment
Findings, scope and quotation
- 01
Consumption profile
Main supply and selected circuit measurements.
- 02
Geyser plan
Control settings or dedicated PV water-heating design.
- 03
Solar design
Panels, inverter, batteries, protection and essential loads.
- 04
Optimisation report
Recommended settings for an existing system.
- 05
Savings estimate
Grid energy reduction using measured assumptions.
- 06
Formal quotation
Equipment and installation pricing after assessment.
Final savings depend on actual usage. ISI confirms the scope before issuing the quotation.
Get started
Start with your electricity bill
ISI will assess how your home uses power and identify the first improvement that offers a sensible return.
- 01Provide two to three recent electricity bills.
- 02Tell us about your geyser, pool and major electrical loads.
- 03Share inverter and battery details if a system is already installed.
- 04Book an on-site assessment and CT measurement.
- Phone
- 081 389 7347
- info@isipower.co.za
Book your assessment
We will confirm a time and what to have ready.
Sources & assumptions
Tariff figures
- Eskom Distribution tariff books and tariff history (eskom.co.za)
- NERSA MYPD6 redetermination and 2026 decision (nersa.org.za)
- Statistics South Africa, Municipal finances and electricity: 11 years in perspective
- City of Tshwane tariff increase announcement, 2 July 2026 (tshwane.gov.za)
Equipment
- GeyserWise MWS Controller product and installation information (geyserwise.com)
Final PV string design must use the selected panel's Voc, Vmp, temperature correction, controller limits, element resistance and the manufacturer's current installation guide.
- Eskom average tariff increases provide a national reference. Municipal retail tariffs, including Tshwane, differ by tariff structure.
- The 8.83% figure applies to Eskom from 1 April 2027. The City of Tshwane 2027/28 retail increase was not yet approved as at 14 September 2026.
- The household opportunity is an illustrative sales example, not a prediction of any specific home’s performance.
Figures current as at .