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PowerOptimal Elon® Smart User Manual v1.19

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img-003.pngimg-003.pngPowerOptimal Elon® Smart Thermostat

User Manual

Version number: 1.19

Version date: 2025/12/28

Enquiries: [email protected]

Address: 88 12th Avenue

Kleinmond

7195

Please note: Always check the Elon Smart website for the latest version of this manual.

Patented: GB2583814, ZA2019/02129, ZA2022/08516, EP4100979,

US 12,112,914, GB2618349, ZA2024/08399

Patents pending: PCT/ZA2024/050065, CH2023800381161, US 18/861,142, EP4519612, AU2023264634, ZA2023/11726, ZA2024/08845

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SAFETY WARNING

  • The Elon® Smart should only be installed in standard Kwikot electric geysers. It is NOT compatible with other geyser brands.
  • This is NOT the Installation Manual. Installers should read and follow the Installation Manual instructions. The Installation Manual can be downloaded from https://poweroptimal.com/manuals.
  • We strongly recommend that the Elon Smart is only installed by a qualified plumber or electrician.
  • If you are installing solar PV together with the Elon Smart, we strongly recommend that you use a reputable and experienced solar photovoltaic (PV) system installer to install your solar PV modules, and strictly according to the installation instructions in the full Elon Smart installation manual, which is available for download from the PowerOptimal website.
  • Installers should wear the appropriate safety and personal protective equipment (for example a safety harness and/or fall protection equipment when working at height).
  • The solar PV modules and wiring installation must be signed off by an electrical contractor registered with the Department of Labour (the so-called “wireman’s licence”) The electrician must provide you with a supplementary Certificate of Compliance (CoC) once installation is completed. (A supplementary CoC is not required if only the Elon Smart is installed with no solar PV.)
  • Solar PV modules exposed to the sun are live (i.e. will produce electricity) and can give an electric shock. Special care should be taken and only trained solar PV installers should install the modules.
  • Do not attempt to alter or service the electrical installation, or open the Elon® Smart unit for any purpose.
  • Use the Elon® Smart only for its intended purpose.
  • Always make sure that every wiring connection is properly tightened.
  • Do not earth either of the solar module wires (but do earth the frames).
  • All installation wiring should be at least 2.5mm².
  • Avoid coiling, since DC switching can create damaging spikes.
  • Keep all wires as short as possible.

Refer to the PowerOptimal website for the following:

img-005.pngimg-005.pngElon® Smart Installation Manual

www.poweroptimal.com/manuals

img-006.pngimg-006.pngTraining videos for electricians

www.poweroptimal.com/training

Table of Contents

Table of Contents 4

1. Elon Smart User Guide 5

A. Installing and using the Elon Smart app 5

B. How to maximise your savings 11

C. Maintenance 12

D. What to expect in terms of performance 13

Appendix A. Configuring your Elon Smart Thermostat 17

Appendix B. Alarms and Basic Troubleshooting 19

Appendix C. Solar yield 26

C1. Solar irradiance levels 26

C2. Geographic features 27

C3. Azimuth / horizontal angle 27

C4. Inclination or tilt angle 27

C5. Shading 27

C6. Ambient temperature 28

C7. Minimum distance from roof edges 28

Appendix D. Deciding on Size of Solar Array 29

Appendix E. PV array and geyser (water heater) element matching 33

Appendix F. Technical Specification Summary: Elon® Smart 34

Appendix G. Surge Protection Device (SPD) Recommendations 35

G1. SANS 10142-1 The wiring of premises Part 1: Low-voltage installations 35

G2. SANS 60364-7-712 (2018) Low Voltage Electrical Installations: Requirements for special installations or locations – Solar photovoltaic (PV) power supply systems 36

Appendix H. IEC/SANS and EMC Test Certificates: Elon® Smart 39

Appendix I. Warranty 42

Appendix J. Terminology 43

Notes 44

1. Elon Smart User Guide

A. Installing and using the Elon Smart app

  1. Install the Elon Smart app on your smart phone by searching for “Elon Smart Water” in the Google Play Store (Android) or Apple App Store (iPhone). Alternatively, scan one of the QR codes provided below.

Elon Smart App

for iPhone:

Apple App Store

Elon Smart App for Android:

Google Play Store

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Scan this QR code with your Android phone Scan this QR code with your iPhone to

to install the app from the Google Play Store install the app from the Apple App Store

  1. Open the Elon Smart app on your phone.
  2. Your installer will have stuck an Elon Smart QR code sticker to the inside of your distribution board (DB) that looks like this:

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  1. Tap the (+) button on the bottom right to add the Smart thermostat.
  2. The app will display the scanning screen called “Add Thermostat”. Scan the QR code by placing it horizontal and centred on the screen. (If the code does not want to scan, try moving the phone closer and further from the QR code. Try rotating the phone into landscape mode.)
  3. The app should take you back to the main screen after the thermostat has been added:

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You can now see your smart geyser in the app. You can see the current temperature and whether it is in solar or grid mode.img-013.pngimg-014.pngimg-013.pngimg-014.png

  1. Please note: If the installer has not configured your thermostat and connected it to your Wi-Fi network yet, please follow the instructions in Appendix A. Configuring your Elon Smart Thermostat before continuing.
  2. Tap anywhere on the geyser name to go to a screen with more information:

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  1. Use the tabs above the graph to view graphs for “Today”, “Yesterday”, “This Week”, “This Month” or “This Year”.
  2. img-016.pngimg-016.pngYou can press the “Heat With Grid Now” button to heat the geyser to its temperature set point with grid power (for example on a rainy day when there was too little solar energy production).
  3. img-017.pngimg-018.pngimg-017.pngimg-018.pngOn the home screen, tap the Settings (gear) button to access the Thermostat Settings screen, where you can change the geyser / thermostat name, configure the Wi-Fi and change the solar temperature set point and the grid temperature set point, as well as the Heating Profile:

Table 1.1 Heating Profile options

Heating Profile option

Solar power use

Grid power use

Comments

Grid Only

Never

Always

Select this option if you don’t have any solar panels installed.

Solar Only

Always

Never

ONLY use solar power. NEVER use grid power.

Morning Shower

Always except for 3 am – 5 am

3 am – 5 am

Solar power will be used whenever available, and grid power will only be used early in the morning to boost water temperature to the Grid set point if the temperature is lower than that.

Evening Shower

Always except for 5 pm – 7 pm

5 pm – 7 pm

Solar power will be used whenever available, and grid power will only be used in the late afternoon to boost water temperature to the Grid set point if the temperature is lower than that.

Morning and Evening Shower

Always except for 3 am – 5 am & 5 pm – 7 pm

3 am – 5 am &

5 pm – 7 pm

Solar power will be used whenever available, and grid power will only be used in the early morning and late afternoon to boost water temperature to the Grid set point if the temperature is lower than that.

Holiday Mode

Off

Off

System switched off completely

Custom Profile

Whenever not in grid mode

Custom

Use the Custom Profile option to set your own grid heating timers.

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Standard Heating Profiles (solar in orange, grid in blue)

Custom grid heating profile settings

    1. If you want to set your own times for when the water should be heated with grid power, select the “Custom Profile” heating profile (see Figure 4.19).
    2. img-020.pngimg-020.pngIf you have already configured some custom profiles, you can select the custom heating profile you wish to activate (see Figure 4.20).
    3. img-021.pngimg-021.pngIf you have not configured any custom grid heating profiles yet or want to add a custom profile, tap “New Profile”.
    4. You can also edit an existing profile by selecting that profile and tapping “Edit Profile”.
    5. Once you’re on the custom profile editing screen (see Figure 4.21), give your custom profile a name so you can easily select it in future.
    6. img-022.pngimg-022.pngYou can add time slots for grid heating for the different days of the week, as well as target water temperatures. Note that you can add multiple time slots in a single custom profile by tapping “Add Additional Timer”.
    7. img-023.pngimg-023.pngOnce done with setting up your custom grid heating profile, don’t forget to tap “Save”.

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Fig 4.19 Select “Custom Profile” Fig 4.20 Choose a custom profile Fig 4.21 Set grid time slots

  1. If there are any problems with the installation, an alarm will display below the thermostat settings, indicated by a red exclamation mark (!). See Appendix A for a list of alarms and how to resolve them (if needed).
  2. Once you have cleared all the issues, then no more alarms will be displayed on the configuration settings screen.

Please note: DO NOT install a separate timer on the AC side to try and regulate mains power use. Use only the Elon Smart app to control mains power use. If you install a second timer, it will work at cross-purposes with the Elon and you will reduce performance and hot water availability.

img-027.pngimg-027.pngTo delete a smart geyser from the app, tap and hold on the device that you want to delete on the home screen.

A prompt will pop up for you to confirm whether you want to delete the device, as shown on the screenshot to the right.

img-028.pngimg-029.pngimg-028.pngimg-029.pngTo see the current version of the app and the current versions of all software on the Elon Smart Thermostat, tap on the hamburger menu ≡ in the top right of the home screen and then tap “About”. The left tab shows the mobile phone app version, whilst the right tab shows the device software versions.

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To set your electricity tariff (so that you can see your savings), or to set your country if you are based outside of South Africa, tap on the hamburger menu ≡ in the top right of the home screen and then tap “Profile Settings”. You can fill in your electricity tariff and set your country on the Profile Settings screen.

To get help:

You can also tap the “Help Centre” menu item to access the Help Centre, where you can find information in the Elon Smart knowledge base, download manuals and troubleshooting guides and talk to the Elon Smart support bot or open a support ticket.

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Menu items Profile Settings Help Centre

B. How to maximise your savings

Here are some general water-, energy- and money-saving tips, whether you have solar PV modules installed with your Elon Smart or not:

  • Install water-saving (low-flow) showerheads. This can reduce your hot water use by 20 to 40%. (You will also save on your water bill!)
  • Shower, don’t bath.
  • Reduce shower duration.
  • Check that your geyser is well insulated. This includes the inlet and outlet pipes!

If you have solar PV modules connected to your Elon Smart thermostat, here are some additional money-saving tips:

  • The best way to maximise your savings is to set the Heating Profile to “Solar Only”. This will ensure that the unit will never use grid (mains) power for heating water. You can still boost with grid power (for example on a cloudy day) by pressing the “Heat With Grid Now” button. This will heat with grid power up to the grid temperature setpoint once, before returning to the previous setting.
  • However, the "Solar Only" setting will only be feasible if you have enough solar PV modules for your household’s level of hot water use. Even if you have a smaller system, you might be able to run it on “Solar Only” for most of the year, depending on your location. However, there will be some very cloudy or rainy days when there is just not enough sunlight.
  • If “Solar Only” doesn’t work for your household, select the “Morning Shower” or “Evening Shower” Heating Profile and see if this works for you. You can also adapt your showering habits to solar power availability.
  • It is generally best to shower in the mornings for maximum savings, since then the water can be reheated during the day.
  • A bigger geyser (200L vs 150L or 100L) is better for maximising savings, since more energy from the sun can be stored in the bigger volume of water.

C. Maintenance

The Elon® Smart has been designed to last for a very long time and has no moving parts aside from three electrical relays. No maintenance is required on the Elon® Smart thermostat.

C1 Solar PV module maintenance

  1. Perform regular visual checks (at least once a year). Check for soiling or any visible damage to any of the modules.
  2. If the modules have been soiled by dirt, dust, debris, bird droppings or any other materials, use water only and a sponge or soft cloth to clean them. Do the cleaning early in the morning or late in the afternoon, as the modules are hot during the day. Avoid using a water jet that may leave streaks on the modules.
  3. Visually inspect cables for any degradation or loose fittings.
  4. Look for any shading problems, such as trees that may have grown.
  5. An electrician can check solar power production on a sunny day to ensure that the system is still producing power at expected levels. A thermal imaging camera can be used to inspect modules for hot spots.
  6. Follow any specific maintenance instructions from the solar PV module manufacturer.

D. What to expect in terms of performance

D1 Hot water production

Heating water takes a LOT of energy. A household geyser can use up to 40% or even 50% of a house’s electricity. Heating a single 200 litre geyser from 15 °C to 60 °C will use over 10 kWh. This is about the same amount of energy burnt by a person running a distance of over 100 km at 10 km/hr, or enough energy to watch more than 120 hours of TV[1].

The more solar panels you have on your roof, the faster the Elon® Smart system will heat your water. Typically, the number of panels has been selected to heat water over most of the sunlight hours (from morning to afternoon). This will be slower than heating water using grid electricity. So, you can expect a gradual temperature rise from morning to afternoon.

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As one would expect, hot water production increases with increase in size of the solar PV array. Keep in mind that these numbers are averages over the year. This means that you should expect lower numbers at certain times of year (for example during winter for the Western Cape & during the rainy season for Gauteng).

D2 Impact of location and seasons

The amount of energy from the sun depends on your location, the time of year as well as the orientation of your solar panels. The best direction for panels in South Africa is to face north, at an angle of about 25 to 35° from horizontal.

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Although Gauteng (Johannesburg / Pretoria) & Cape Town may seem quite similar in terms of total solar energy per year, Cape Town has winter rainfall and Gauteng has summer rainfall. This leads to Cape Town having much lower solar electricity production than Gauteng in winter (see the below graph).

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D3 Payback period

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As can be seen from the graph above, payback period decreases as number of solar panels increases, and is also different for Johannesburg, Cape Town and Durban (eThekwini)[2].

The reason that payback period improves (decreases) as number of solar panels increases, is because there are some fixed costs (such as engineering design & safety components) and some costs that do not scale linearly with array size (such as labour, wiring, mounting kit costs, etc.).

Appendix A. Configuring your Elon Smart Thermostat

Please note: You need to be at home and within Wi-Fi distance from your Elon Smart to change configuration settings.

  1. img-039.pngimg-039.pngOpen the Elon Smart App home page.
  2. Tap the Settings (gear) button on the right of your Elon Smart thermostat.
  3. The application requests confirmation to switch to the Smart Thermostat’s hotspot (Figure A1).
  4. Select “CONNECT”
  5. The application should display the “Thermostat Settings” screen (Figure A2)
  6. img-040.pngimg-040.pngIf the Wi-Fi network has not been configured yet, tap the Wi-Fi Hotspot item. Otherwise skip to Step 15.
  7. The application searches for the available networks and displays them in a list (Figure A3).

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Figure A1 Network change Figure A2 Configure screen Figure A3 Select Wi-Fi

  1. Tap on the Wi-Fi network you want the Smart Thermostat to use.
  2. The application will ask for a password for the network you selected (Figure A4).
  3. Enter the password and tap “Test Connection”.
  4. If you entered the password correctly the application should take you back to the configuration screen and the network should be green.
  5. img-044.pngimg-044.pngNext configure the address. Tap the “Installed Adress” item.
  6. The app should connect to the server and obtain a list of addresses corresponding to your GPS co-ordinates (Figure A5). (You might need to switch on your phone GPS and allow the app to use your location services.)
  7. Select the correct address.
  8. The app should take you back to the “Thermostat Settings” screen (Figure A6).
  9. img-045.pngimg-045.pngGo to the top field called “Thermostat Label” and enter a new name for the smart thermostat. This will be used to identify this smart thermostat or geyser in your app.
  10. img-046.pngimg-046.pngNow set the “Target Solar Temperature” and “Target Grid Temperature” set points. It is best for savings and optimal solar power usage to select a lower temperature set point for grid power than for solar power. 65 °C on Solar and 50 °C on Grid are good set points.

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Figure A4 Enter Wi-Fi password Figure A5 Select address Figure A6 Heating settings

  1. Next you can set the “Heating Profile” according to your preference. Select how the household wishes to use the hot water generated by the Smart thermostat (refer back to Table 1.1). It is typically best to start with the “Morning and Evening Shower” profile.

Appendix B. Alarms and Basic Troubleshooting

The Elon Smart has a helpful alarm system that detects and reports common issues. See the below list for the various alarms and how to resolve them.

Please note: general users should NOT attempt to carry out the actions for installation technicians / electricians (the right-most column).

Always check that you have the latest version of the app by going to the “Elon Smart Water” app in your app store.

ID

Alarm message

How to resolve the alarm: USERS

How to resolve the alarm: TECHNICIANS / ELECTRICIANS

0

Element Faulty

Contact your installer / electrician

    1. Check that the thermostat is inserted correctly.
  1. If that does not clear the alarm, measure element resistance and replace if necessary.

1

Switch Failed

Contact our help chat

Contact our help chat

2

DC Disconnect Failed

Contact our help chat

Contact our help chat

3

No Power on AC Input

This can be due to several reasons:

    1. There is no AC power connected to the Elon Smart
    2. AC power is off at the circuit breaker in the DB board or at the AC isolator close by the Elon Smart unit.
    3. There is a power failure or loadshedding.
    4. You have a geyser timer installed.

This alarm won’t prevent the Elon Smart unit from functioning and heating water with solar (DC) power as long as there is solar power available.

You can clear the alarm by switching the AC power on (where applicable), setting the Elon Smart heating policy to Solar Only (see Table 1.1) or you can leave it until AC power returns.

See to the left

4

Measurement Failure

Contact our help chat

Contact our help chat

5

Disconnected for Safety

When there is a safety-related alarm condition, the Elon Smart will disconnect power from the geyser. To clear this alarm, you need to clear the other safety-related alarm(s). 

See to the left

6

Water Temperature Measurement Failure

Contact our help chat 

Contact our help chat

7

Ambient Temperature Exceeded

  1. Check the installation. If the geyser is installed in direct sunlight, see if you can provide shade to the geyser end space area where the Elon Smart is located.
  2. Reduce temperature set point by 5 degrees.
  3. Wait until temperatures cool down. The Elon Smart will start up again.
  4. Contact our help chat if the above doesn’t clear the alarm.

See to the left

8

DC Wiring Insulation Failure

Contact your installer / electrician.

To operate the Elon Smart whilst the insulation fault has not been located and resolved, you can set the heating profile to Grid Only or switch off the DC disconnect switch.

    1. Check solar panels and DC wiring for insulation faults.
    2. Confirm that element is functioning correctly (check element resistance and continuity).
    3. To operate the Elon Smart whilst the insulation fault has not been located and resolved, you can set the heating profile to Grid Only or switch off the DC disconnect switch.

9

Insulation Self-Test Failed

Contact your installer / electrician

Check earth wiring. Make sure both earth straps are connected securely to the geyser earth stud.

10

AC Wired to DC Input

Contact your installer / electrician

Wire AC to correct input (see Chapter 4 in the Installation Manual).

11

DC Wired to AC Input

Contact your installer / electrician

Wire DC to correct input (see Chapter 4 in the Installation Manual).

12

No Power on DC Input

This can be due to several reasons:

    1. There is no DC power connected to the Elon Smart
    2. DC power is off at the DC disconnect switch close by the Elon Smart unit.
    3. There is an issue with the DC wiring or solar PV installation.
    4. It is extremely dark and overcast during daytime. (The alarm is not active when the sun is less than 15 degrees above the horizon.)

This alarm won’t prevent the Elon Smart unit from functioning and heating water with grid (AC) power as long as there is grid power available.

You can clear the alarm by:

      1. switching the DC power on (where applicable);
      2. setting the Elon Smart heating policy to Grid Only (see Table 1.1);
      3. leaving it until DC power returns; or
      4. contacting your installer / electrician to inspect and fix the DC wiring and/or solar PV installation.

See to the left

13

DC Input Reversed

Contact your installer / electrician.

The wiring on the Solar input has been installed incorrectly (in reverse). The DC+ (positive) wire has been connected to the DC- (negative) terminal on the Elon Smart and the DC- (negative) wire has been connected to the DC+ (positive) terminal on the Elon Smart. Swap the DC wires around (see Chapter 4 in the Installation Manual).

14

Hot Connection

Contact your installer / electrician.

Elon Smart not correctly inserted into geyser element. Switch off all power to the Elon Smart and re-seat (reinsert) the Elon Smart.

15

RTC Failed

Contact our help chat

Contact our help chat

16

Power Unstable

  1. If it is intermittent or temporary and occurring during loadshedding or grid power failures, you can ignore this alarm.

If the alarm persists whilst grid power is available, contact your installer / technician.

  1. Check that wiring to Elon Smart is properly connected and not loose.
  2. Check whether geyser circuit breaker in DB or the geyser’s AC isolator are faulty or wiring is not properly connected.

If none of the above are present, then contact our help chat.

17

Server Not Available

  1. Check that your home Wi-Fi network has internet connectivity.
  2. img-050.pngimg-050.pngCheck the Elon Smart Wi-Fi settings on the thermostat settings screen (access by tapping the gear icon in the app when at home).
  3. If your Wi-Fi router is far away from your geyser, the Wi-Fi signal might be too weak. This can be improved with a Wi-Fi extender or signal booster.

If none of the above works, try rebooting your Elon Smart by switching off the geyser circuit breaker on your house DB board at night for 2 minutes.

See to the left

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Appendix C. Solar yield

Note: only basic information is provided here. Your solar PV installation design engineer or technician should advise on the best configuration for your specific location, roof structure, etc.

The yield produced by solar PV modules depends on several factors:

  • Solar irradiance levels at your location (which varies with time of day, season and weather conditions)
  • Geographic features at your location (e.g. mountains or buildings causing morning or afternoon shade)
  • Azimuth and tilt of the modules
  • Shading
  • Ambient temperature (also influenced by wind)

C1. Solar irradiance levels

The map below shows the general solar irradiance levels (GHI or Global Horizontal Irradiance) in South Africa[3]:

img-055.pngimg-055.png

You can expect the following approximate energy generation from solar modules for various locations[4]:

Location

Electricity generated kWh/kWp per year

Bloemfontein

2055

Cape Town

1762

Durban

1570

Johannesburg / Pretoria

1871

Mbombela

1766

Port Elizabeth

1698

Upington

2075

C2. Geographic features

Major geographical features (such as hills or mountains) can reduce the total solar yield.img-056.pngimg-056.png

C3. Azimuth / horizontal angle

The azimuth refers to the horizontal orientation of the modules – in the Southern Hemisphere, by how many degrees they are oriented away from north

Due north is best in the Southern hemisphere. Modules should preferably not be oriented more than 15º away from due north.

C4. Inclination or tilt angle

The tilt angle refers to the vertical orientation of the modules – a rough guide is that the modules should be tilted at the site’s latitude. For example, Musina is 22º S, Pretoria & Johannesburg are 26º S, Bloemfontein is 29º S, Durban is 30º S and Cape Town & Gqeberha (Port Elizabeth) are 34º S.

To optimise winter performance, one can add 15º to the tilt angle. (Note: as long as you are within about 15º of the optimal latitude, the loss in efficiency is not substantial.)

C5. Shading

Solar modules lose a lot of efficiency if even a small part of the module is shaded. For example, just 3% shading can cause a 25% loss in power! Shaded cells on a module also causes hotspots, which will reduce module lifetime.

It is thus important to place the solar modules on a rooftop area that is free from shading for as much as possible of the day (and throughout the year).

C6. Ambient temperature

Solar PV modules’ performance decreases with increasing temperature. Wind will reduce the temperature of the solar array and will thus improve performance. Thus, it is important to install rooftop solar modules with an air gap of at least 40 mm between the modules and roof[5].

C7. Minimum distance from roof edges

Your solar PV design engineer should prescribe minimum clearance from roof edges that should be maintained for your area based on climatic and wind conditions. Typically, a minimum clearance of 20 to 30 cm should be maintained.

Appendix D. Deciding on Size of Solar Array

Terminology used

img-057.jpgimg-057.jpg

Solar power is generated by solar cells, which are arranged in framed modules. The total set of solar PV modules installed is referred to as a solar PV array[6].

The table below provides a basic guide to selecting the size of the solar PV array based on number of people in the household and/or hot water use. Minimum recommended size is 1 kWp. Read on for a more detailed guide.

Solar PV array size

(kWp)

Showers per day*

50%+ of daily hot water use provided for how many people?

How many people off-grid for hot water?

Typical number of solar PV modules

1 – 1.6

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2 - 3 modules

1.6 - 2

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3 - 4 modules

2 - 3

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4 - 5 modules

* 6-minute showers at 40 °C with 8 litre/min (low-flow) showerheads

TABLE D1. ANNUAL AVERAGE LITRES OF WATER HEATED PER DAY

The below example table indicates the average number of litres of water per day that the system will heat from 15 to 60 °C over a year period for different solar array peak power ratings. (The amount of water heated will vary with weather conditions, by geographic location and by season. Water heated per day will be significantly lower in winter and significantly higher in summer. These numbers indicate heating capacity – i.e. if no hot water is used on a given day, there will be less water heated on that day. This is only an approximate guide.)

 

Solar + Elon®

Annual average litres of water heated per day for X kWp installed solar capacity

Location

kWh/kWp/yr

0.8 kWp

1 kWp

1.2 kWp

1.4 kWp

1.6 kWp

1.8 kWp

2 kWp

2.5 kWp

3 kWp

3.5 kWp

Bloemfontein

1894

80

99

119

139

159

179

199

249

298

348

Cape Town

1624

68

85

102

119

136

154

171

213

256

299

Durban

1447

61

76

91

106

122

137

152

190

228

266

Jhb/Pretoria

1724

72

91

109

127

145

163

181

226

272

317

Mbombela

1627

68

85

103

120

137

154

171

214

256

299

Port Elizabeth

1565

66

82

99

115

132

148

164

205

247

288

Upington

1912

80

100

121

141

161

181

201

251

301

352

Saldanha

1623

68

85

102

119

136

153

170

213

256

298

Example:

For a solar array of 1.2 kWp, an installation in Johannesburg would yield about 1724 kWh/kWp/yr, or 1724 x 1.2 kWp = 2069 kWh/yr. This would be sufficient to heat on average 109 litres of water per day. For a family of 2 each using 80 litres of hot water per day, this would provide about 109 ÷ (80 x 2) or 68% of the annual hot water requirement.

TABLE D2. ANNUAL AVERAGE NUMBER OF SHOWERS PER DAY

The below table indicates the average number of showers per day for which the system will supply hot water over a year period for different solar array peak power ratings. (The amount of water heated will vary with weather conditions, by geographic location and by season. Water heated per day will be significantly lower in winter and significantly higher in summer. These numbers indicate heating capacity – i.e. if no hot water is used on a given day, there will be less water heated on that day. This is only an approximate guide.)

 

Solar + Elon®

Number of showers per day (based on annual average) for X kWp installed solar capacity

Location

kWh/kWp/yr

0.8 kWp

1 kWp

1.2 kWp

1.4 kWp

1.6 kWp

1.8 kWp

2 kWp

2.5 kWp

3 kWp

Bloemfontein

1894

2.4

3.0

3.6

4.2

4.8

5.4

6.0

7.5

9.0

Cape Town

1624

2.0

2.6

3.1

3.6

4.1

4.6

5.1

6.4

7.7

Durban

1447

1.8

2.3

2.7

3.2

3.6

4.1

4.6

5.7

6.8

Jhb/Pretoria

1724

2.2

2.7

3.3

3.8

4.3

4.9

5.4

6.8

8.2

Mbombela

1627

2.1

2.6

3.1

3.6

4.1

4.6

5.1

6.4

7.7

Port Elizabeth

1565

2.0

2.5

3.0

3.5

3.9

4.4

4.9

6.2

7.4

Upington

1912

2.4

3.0

3.6

4.2

4.8

5.4

6.0

7.5

9.0

Saldanha

1623

2.0

2.6

3.1

3.6

4.1

4.6

5.1

6.4

7.7

The table is based on 6-minute showers at 40 °C and 8 litres/min low flow showerheads. Old showerheads can use up to 15 litres/min and would substantially reduce the number of showers.

Example:

For a solar PV array of 2.5 kWp, an installation in Johannesburg would yield about 1724 kWh/kWp/yr, or 1724 x 2.5 kWp = 4 310 kWh/yr. This would be sufficient for about 6 to 7 showers per day.

TABLE D3. PERCENTAGE OF ANNUAL HOT WATER REQUIREMENT

The below example table indicates what % of the annual hot water requirement will on average be supplied by the system for 2 people each using 80 litres of hot (60 °C) water per day. (The amount of water heated will vary with weather conditions, by geographic location and by season. Water heated per day will be significantly lower in winter and significantly higher in summer. These numbers indicate heating capacity – i.e. if no hot water is used on a given day, there will be less water heated on that day. This is only an approximate guide.)

Solar + Elon®

Annual average % of hot water requirement supplied for 2 people each using 80 litres of hot water per day for X kWp installed solar capacity

Location

kWh/kWp/yr

0.8 kWp

1 kWp

1.2 kWp

1.4 kWp

1.6 kWp

1.8 kWp

2 kWp

2.5 kWp

3 kWp

Bloemfontein

1894

50%

62%

75%

87%

99%

112%

124%

155%

187%

Cape Town

1624

43%

53%

64%

75%

85%

96%

107%

133%

160%

Durban

1447

38%

47%

57%

66%

76%

85%

95%

119%

142%

Jhb/Pretoria

1724

45%

57%

68%

79%

91%

102%

113%

142%

170%

Nelspruit

1627

43%

53%

64%

75%

85%

96%

107%

134%

160%

Port Elizabeth

1565

41%

51%

62%

72%

82%

92%

103%

128%

154%

Upington

1912

50%

63%

75%

88%

100%

113%

126%

157%

188%

Saldanha

1623

43%

53%

64%

75%

85%

96%

107%

133%

160%

Examples:

An array of 1.2 kWp will provide approximately 64% of the annual hot water requirement for a family of two people in Cape Town.

An array of 2 kWp will provide approximately 124% x (2 people / 4 people) = 62% of the annual hot water requirement for a family of four people in Bloemfontein.

Appendix E. PV array and geyser (water heater) element matching

It is important to match PV array specifications and heating elements for maximum power transfer efficiency. See the below table for the recommended heating element power rating for different solar array sizes.

Contact PowerOptimal for advice on module-element matching if module properties are significantly different to typical values or for advice on bifacial, high current & high voltage modules.

TABLE E1. GUIDE: ELON SMART PV ARRAY AND GEYSER (WATER HEATER) ELEMENT MATCHING

Solar PV array size

(kWp)

Best matching geyser element size

(kW)

2nd choice geyser element size*

(kW)

Geyser (water tank) size

(litres)

1 – 1.6

4

3

100 - 200

1.6 – 2

3

4 or 2

100 - 200

2 – 3

3

4

150 – 300

* Second choice element size would reduce efficiency by 10 – 20%.

DO NOT DEVIATE FROM THE RECOMMENDED MODULE-ELEMENT MATCHING CONFIGURATIONS WITHOUT CONSULTING POWEROPTIMAL.

Maximum allowed solar PV array specifications at Standard Test Conditions (STC):

Isc < 15A Voc < 230V Power < 3 kWp

Appendix F. Technical Specification Summary: Elon® Smart

Refer to the PowerOptimal website for the full Technical Specification www.poweroptimal.com/specifications

Rated input voltage

230V AC, 230V DC

Rated input current

18A AC, 15A DC

Mains (AC) voltage range

230V +10% -15%

System power supply

Solar PV DC or 230V AC mains

Power consumption

3W on either AC or DC (solar) power

Solar voltage

30 – 230 V DC

Thermostat

Electronic thermostat with 0.5 °C accuracy

Safety

Electromechanical thermal cutout

Reverse polarity protection

For solar PV connections

Lightning protection

8 kA

Self-tests

Component failure, wiring failure, element failure, insulation failure, hot connections

Enclosure ingress protection rating

IP40

Annual energy production compared to inverter-based system

> 90% when solar PV array and geyser element are matched correctly

Standards conformance

SANS 60730-1, SANS 60730-2-9, SANS / EN 301 489-1, SANS / EN 301 489-17, ICASA Type Approval, LoA from NRCS

Dimensions & weight

23 x 12 x 11 cm, 0.3 kg. Box dimensions: 27.6 x 17.5 x 13.5 cm.

Patents

Granted: ZA 2019/02129, GB2583814B, ZA 2022/08516, EP 4100979, US 12,122,914, GB2618349

Pending: PCT/ZA2024/050065, GB2618349, ZA2024/08399, CH2023800381161, US 18/861,142, EP23723798.7, AU2023265634, ZA2024/08845

Registered Designs

ZA F2022/00962 (granted), F2022/00963 (granted)

Communications link

Wi-Fi Client, Wi-Fi Hotspot (2.4 GHz)

Measurements

AC energy, voltage, current (5%)

DC energy, voltage, current (5%)

Temperature: water & ambient

Data logging

15-second data retained for 14 days

5-minute data retained for 366 days

Other features

Mobile app for installers and users

Full installation self-check

Remote firmware upgrades

50 000+ switching operations on thermostat

It is important to match modules and heating elements for maximum power transfer efficiency. See the tables in Appendix E for the recommended heating element power rating for different solar module specifications and array configurations.

Appendix G. Surge Protection Device (SPD) Recommendations

This Appendix outlines under which circumstances a Surge Protection Device should be installed as part of a solar PV system installation such as the Elon® Smart.

G1. SANS 10142-1 The wiring of premises Part 1: Low-voltage installations

Please note: compliance with SANS 10142-1 is compulsory for all electrical installations as per the Occupational Health & Safety Act.

SANS 10142-1 states the following with regards to surge protection:

6.7.6 Surge protection

6.7.6.1 Surge protective devices (SPDs) may be installed to protect an installation against transient overvoltages and surge currents such as those due to switching operations or those induced by atmospheric discharges (lightning). NOTE A risk assessment may be performed in accordance with annex Q. The Installation of SPDs is necessary where structures are equipped with external lightning protection systems (LPS) as in accordance with SANS 10313.

As can be seen above, surge protection is optional and based on a risk assessment as per Annex Q.

The risk assessment is as per the following table from SANS 10142-1 (2020):

img-092.pngimg-092.png

Note that the “Service Line” referred to above is the incoming (AC) line for the house.

Here is a lightning density map for South Africa as provided in SANS 10142-1:

img-093.pngimg-093.png

G2. SANS 60364-7-712 (2018) Low Voltage Electrical Installations: Requirements for special installations or locations – Solar photovoltaic (PV) power supply systems

Section 712.443.5.101 of SANS 60364-7-712 requires a Surge Protection Device to be installed on the DC side of the installation where the length (L) of the DC cables (from PV array to Elon® Smart or inverter) exceeds the critical length Lcrit as follows:

A Surge Protection Device is required where L ≥ Lcrit

The critical length Lcrit depends on the type of PV installation and is calculated according to the following table:

Type of installation

Individual residential premises

Terrestrial production plant

Service / Industrial / Agricultural Buildings

Lcrit (in meter)

115/Ng

200/Ng

450/Ng

where Ng = lightning strike density (number of strikes/km²/yr)

The length of DC cables L is the sum of:

  • distances between the inverter(s) and the junction box(es), while observing that the lengths of cable located in the same conduit are counted only once, and
  • distances between the junction box and the connection points of the photovoltaic modules forming the string, observing that the lengths of cable located in the same conduit are counted only once.

For the Elon® Smart, distance L is the length of DC cables from PV array to the Elon® Smart.

On the next page is a national lightning ground stroke density map for South Africa[7].

From this map, the lightning strike density (Ng) range for major cities are as follows:

City

Lightning strike density Ng (strikes/km²/yr)

Lcrit (m)

Individual residential premises

Service / industrial / agricultural buildings

Cape Town

0.02 to 4

29

113

Stellenbosch

0.02 to 4

29

113

Worcester

0.02 to 4

29

113

George

0.02 to 4

29

113

Saldanha

0.02 to 4

29

113

Gqeberha (Port Elizabeth)

0.02 to 4

29

113

Buffalo City (East London)

4 to 6

19

75

King Williams Town

4 to 6

19

75

Beaufort-West

4 to 6

19

75

Musina

4 to 6

19

75

Britstown

6 to 15

8

30

eThekwini (Durban)

6 to 15

8

30

Upington

6 to 15

8

30

Pietermaritzburg

15 to 21

5

21

Greytown

15 to 21

5

21

Polokwane

15 to 21

5

21

Bloemfontein

15 to 21

5

21

Queenstown

15 to 21

5

21

Vryburg

15 to 21

5

21

Mahikeng

15 to 21

5

21

Mbombela (Nelspruit)

15 to 21

5

21

Kimberley

21 to 27

4

16

Pretoria

21 to 27

4

16

Vereeniging

21 to 27

4

16

Welkom

21 to 27

4

16

Johannesburg

27 to 33

3.5

13

Ermelo

33 to 42

2.5

10

Newcastle

33 to 42

2.5

10

img-094.pngimg-094.png

From Evert & Gijben (2017).

Appendix H. IEC/SANS and EMC Test Certificates: Elon® Smart

img-095.pngimg-095.png

img-096.pngimg-096.png

img-097.pngimg-097.png

Appendix I. Warranty

If the PowerOptimal Elon® Smart (“the Product”) is found to be defective, you will be entitled to a repair or replacement within 2 (two) year of the date of delivery of the Product to you. Please keep your receipt as proof of purchase or register the Elon Smart online. If you are a consumer as defined in the Consumer Protection Act No. 68 of 2008 (“the CPA”), you will be entitled to such remedies as are made available under the CPA in relation to the return of goods.

PowerOptimal will not have any liability or obligation to you where the Product has been subjected to abuse, misuse, improper use, improper testing, negligence, accident, alteration, tampering or repair by a third party.

To the maximum extent permitted by applicable law, in no event shall PowerOptimal be liable for any special, incidental, indirect, or consequential damages whatsoever, including, without limitation, damages for loss of business profits or business interruption, arising out of the use or inability to use this product.

Please note that this unit must be installed by an electrical contractor registered with the Department of Labour. Failure to do so may invalidate this warranty. Please keep the CoC (Certificate of Compliance) issued by the electrical contractor on completion of the installation.

Register your Elon Smart online to get an extended 5-year warranty here:

https://poweroptimal.com/elon-extended-warranty/

Appendix J. Terminology

AC Alternating Current – an electric current that reverses its direction many times a second at regular intervals, with voltage typically varying in the form of a sine wave.

CoC Certificate of Compliance – to be issued by the electrician installing your Elon® Smart system

CPA Consumer Protection Act No. 68 of 2008

DB Distribution board – the main electrical distribution board / panel in your home, containing circuit breakers and switches.

DC Direct Current – an electric current flowing in one direction only. Solar PV modules produce direct current electricity.

Geyser South African term for a water heater

IEC International Electrotechnical Commission

Impp The solar module current at maximum power point (MPP). Manufacturers usually report two Impp values: one at STC and one at NOCT.

kWh A derived unit of energy equal to 3.6 MJ (megajoules). The amount of energy used by a 1 kW electrical device over a period of 1 hour.

kWp or Wp The peak power rating in kilowatt (kW) or watt (W) of a solar module or array – i.e., the output power achieved under full solar radiation. This is usually reported at STC and NOCT.

MPP Maximum power point. This is the point on a solar cell, module or array’s power or I-V (current-voltage) curve that has the highest power output.

NOCT Nominal Operating Cell Temperature (also sometimes referred to as NMOT or Nominal Module Operating Temperature). This refers to the temperature that open circuited solar PV modules will reach under conditions that more closely match actual field operational conditions than STC. The modules are tested at 800 W/m² simulated solar irradiance, 20 °C ambient temperature, 1 m/s wind velocity and open back side mounting. Depending on the quality of the cell / module design, the NOCT can reach anything from 33 to 58 °C[8]. Since solar PV cell power output reduces with increase in temperature, a lower NOCT is better.

PV Photovoltaic – referring to the production of electric current at the junction of two materials exposed to light.

SANS South African National Standards

STC Standard Test Conditions for solar cells – 1000 W/m² simulated solar irradiance and 25 °C solar cell temperature, and an air mass 1.5 spectrum (AM1.5).

Vmpp The solar module voltage at maximum power point (MPP). Manufacturers usually report two Vmpp values: one at STC and one at NOCT.

Notes

  1. 46” OLED TV at 82W. ↑

  2. Calculations based on actual Elon performance, assuming a 20% reduction due to non-optimal user behaviour, an initial electricity tariff of R3.40/kWh and an annual electricity price increase of 8%. ↑

  3. CRSES (Centre for Renewable and Sustainable Energy Studies). Website: http://www.crses.sun.ac.za/files/research/publications/SolarGIS_GHI_South_Africa_width15cm_300dpi.png. Last accessed: 07/04/2017. ↑

  4. Urban Energy Support. Website: http://www.cityenergy.org.za/uploads/resource_274.pdf. Last accessed: 07/04/2017. ↑

  5. D’Orazio M et al. 2013. Performance assessment of different roof integrated photovoltaic modules under Mediterranean Climate. ↑

  6. Image source: http://ohioline.osu.edu/factsheet/AEX-652-11. ↑

  7. Evert CR, Gijben M. 2017. Official South African Lightning Ground Flash Density Map 2006 to 2017. ↑

  8. Source: http://pveducation.org/pvcdrom/modules/nominal-operating-cell-temperature. ↑

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