elen Smart Thermostat Hot Water System

Product Information

Specifications

• Version Number: 1.13
• Version Date: 2024/08/29
• Enquiries: info@poweroptimal.com
• Address: 88 12th Avenue Kleinmond 7195
• Patented: GB2583814, ZA2019/02129, ZA2022/08516, EP4100979
• Patents Pending: US 17/797977, PCT/ZA2023/050022,
  GB2618349

Product Usage Instructions

Safety Precautions

It is crucial to follow safety precautions when installing and
using the Elon Smart:

• Only qualified professionals should install the Elon
  Smart.

• If installing solar PV with the Elon Smart, use an experienced
  solar PV system installer.

• Installers must wear appropriate safety gear.

• All installations must be approved by a registered electrical
  contractor.

• Avoid coiling wires and keep them short to prevent damaging
  spikes.

Installation of Elon Smart App

1. Download the Elon Smart app from Google Play Store (Android) or
   Apple App Store (iPhone).

2. Alternatively, scan the provided QR code with your phone to
   install the app.

3. Open the app and wait for authentication.

4. If the thermostat is not configured, follow the instructions
   before proceeding.

FAQ

Q: Where can I find the full installation manual?

A: The full installation manual can be downloaded from
https://poweroptimal.com/manuals.

Q: Can I install the Elon Smart myself?

A: We strongly recommend that the Elon Smart is only installed
by a qualified plumber or electrician.

PowerOptimal Elon® Smart Thermostat User Manual

Version number: Version date: Enquiries: Address:

1.13 2024/08/29 info@poweroptimal.com 88 12th Avenue Kleinmond 7195

Patented: GB2583814, ZA2019/02129, ZA2022/08516, EP4100979 Patents pending: US 17/797977, PCT/ZA2023/050022, GB2618349

© PowerOptimal (Pty) Ltd 2024. The content of this document is confidential and all rights to the intellectual property and/or information contained herein remain vested in PowerOptimal, except if otherwise agreed in writing.

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 or controller 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.
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Avoid coiling, since DC switching can create damaging spikes. Keep all wires as short as possible.

Refer to the PowerOptimal website for the following:

Elon® Smart Installation Manual

www.poweroptimal.com/manuals

Training videos for electricians

www.poweroptimal.com/training

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PowerOptimal Elon® Smart User Manual Version date: 2024/08/29
Table of Contents

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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 ……………………………………………………………………………………….. 10 C. Maintenance ………………………………………………………………………………………………………………… 11 D. What to expect in terms of performance………………………………………………………………………….12 Appendix A. Configuring your Elon Smart Thermostat……………………………………………………………….15 Appendix B. Alarms and Basic Troubleshooting ……………………………………………………………………….. 17 Appendix C. Solar yield …………………………………………………………………………………………………………. 24 C1. Solar irradiance levels ………………………………………………………………………………………………….. 24 C2. Geographic features ……………………………………………………………………………………………………. 25 C3. Azimuth / horizontal angle …………………………………………………………………………………………… 25 C4. Inclination or tilt angle…………………………………………………………………………………………………. 25 C5. Shading……………………………………………………………………………………………………………………….25 C6. Ambient temperature………………………………………………………………………………………………….. 26 C7. Minimum distance from roof edges ………………………………………………………………………………. 26 Appendix D. Deciding on Size of Solar Array…………………………………………………………………………….. 27 Appendix E. PV array and geyser (water heater) element matching …………………………………………… 31 Appendix F. Technical Specification Summary: Elon® Smart……………………………………………………….32 Appendix G. Surge Protection Device (SPD) Recommendations …………………………………………………. 33 G1. SANS 10142-1 The wiring of premises Part 1: Low-voltage installations……………………………..33 G2. SANS 60364-7-712 (2018) Low Voltage Electrical Installations: Requirements for special installations or locations ­ Solar photovoltaic (PV) power supply systems ………………………………. 34 Appendix H. IEC/SANS and EMC Test Certificates: Elon® Smart…………………………………………………..37 Appendix I. Warranty ……………………………………………………………………………………………………………. 40 Appendix J. Terminology………………………………………………………………………………………………………..41 Notes ………………………………………………………………………………………………………………………………. 42

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PowerOptimal Elon® Smart User Manual Version date: 2024/08/29

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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 Android:
Google Play Store
Scan this QR code with your Android phone to install the app from the Google Play Store

Elon Smart App for iPhone: Apple App Store
Scan this QR code with your iPhone to install the app from the Apple App Store

2. Open the Elon Smart app on your phone. Wait until it says “App is authenticated” at the bottom of the screen.

3. If the installer has not configured your thermostat and connected it to your WiFi network yet, please follow the instructions in Chapter 4E before continuing.
4. 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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PowerOptimal Elon® Smart User Manual Version date: 2024/08/29

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5. Tap the (+)

button on the bottom right to add the Smart thermostat.

6. 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.)

7. The app should take you back to the main screen after the thermostat has been added:

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.

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8. Tap anywhere on the geyser name to go to a screen with more information:

9. Use the grey drop-down menu to view graphs for “Today”, “Yesterday”, “This Week”, “This Month” or “This Year”.
10. You 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).
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11. On the home screen, tap the Configure

(hammer & spanner) button to access the

Configure Thermostat screen, where

you can change the geyser name, configure the

WiFi 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

Solar power Grid power

Profile option use

use

Grid Only

Never

Always

Solar Only Always

Never

Morning Shower

Always except 3 am ­ 5 am for 3 am ­ 5 am

Evening Shower

Always except 5 pm ­ 7 pm for 5 pm ­ 7 pm

Morning and Evening Shower

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

3 am ­ 5 am &
5 pm ­ 7 pm

Comments
Select this option if you don’t have any solar panels installed. ONLY use solar power. NEVER use grid power. 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. 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. 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.

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To delete a smart geyser from the app, swipe left on the device on the home screen as shown in the app image below:

After you have deleted the device, you have 10 seconds to “Undo delete”.

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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 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.
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.

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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
It is recommended that a qualified electrician inspect your solar PV installation at least once a year.
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.

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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% 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 TV1.
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.

As one would expect, hot water production increases with increase in number of solar panels. Keep in mind that these numbers are averages over the year. This means that you should expect a lower number in winter and a higher number in summer.
1 46″ OLED TV at 82W. © PowerOptimal (Pty) Ltd 2024. The content of this document is confidential and all rights to the intellectual property and/or information contained herein remain vested in PowerOptimal, except if otherwise agreed in writing.

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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.

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 Durban2. 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.).
2 Calculations based on actual Elon performance, assuming a 20% reduction due to non-optimal user behaviour, an initial electricity tariff of R3/kWh and an annual electricity price increase of 8%. © PowerOptimal (Pty) Ltd 2024. The content of this document is confidential and all rights to the intellectual property and/or information contained herein remain vested in PowerOptimal, except if otherwise agreed in writing.

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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. Open the Elon Smart App.

2. Tap the Configure

(hammer & spanner) 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 “Configure Thermostat” screen (Figure A2)

6. If the Wi-Fi network has not been configured yet, tap

the right arrow (>) next to the Wi-Fi Hotspot entry.

Otherwise skip to Step 12.

7. The application searches for the available networks and displays them in a list (Figure A3).

Figure A1 Network change

Figure A2 Configure screen

Figure A3 Select Wi-Fi

8. Tap on the Wi-Fi network you want the Smart Thermostat to use. 9. The application will ask for a password for the network you selected (Figure A4). 10. Enter the password and tap “Test Connection”. 11. If you entered the password correctly the application should take you back to the
configuration screen and the network should be green.

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12. Next configure the address. Click on the right arrow (>) next to the address field.
13. 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.)
14. Select the correct address. 15. The app should take you back to the “Configure Thermostat” screen (Figure A6). 16. Go to the top field called “Label” and enter a new name for
the smart thermostat. This will be used to identify this smart thermostat in your app. 17. Now set the “Solar Max. Temp.” and “Grid Max. Temp.” 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.

Figure A4 Enter Wi-Fi password

Figure A5 Select address

Figure A6 Heating settings

18. 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.

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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 0 Element Faulty 1 Switch Failed 2 DC Disconnect Failed 3 No Power on AC Input
4 Measurement Failure

How to resolve the alarm: USERS
Contact your installer / electrician
Contact technical support Contact technical support This can be due to several reasons: a. There is no AC power connected to the Elon Smart b. AC power is off at the circuit breaker in the DB
board or at the AC isolator close by the Elon Smart unit. c. There is a power failure or loadshedding.
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. Contact technical support

How to resolve the alarm: TECHNICIANS / ELECTRICIANS a. Check that the thermostat is inserted correctly. b. If that does not clear the alarm, measure element
resistance and replace if necessary. Contact technical support Contact technical support See to the left
Contact technical support

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ID Alarm message 5 Disconnected for Safety
6 Water Temperature Measurement Failure
7 Ambient Temperature Exceeded
8 DC Wiring Insulation Failure
9 Insulation Self-Test Failed 10 AC Wired to DC Input 11 DC Wired to AC Input

How to resolve the alarm: USERS
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 safetyrelated alarm(s). Contact technical support

How to resolve the alarm: TECHNICIANS / ELECTRICIANS See to the left
Contact technical support

a. 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.
b. Reduce temperature set point by 5 degrees. c. Wait until temperatures cool down. The Elon Smart
will start up again. d. Contact technical support if the above doesn’t clear
the alarm. 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.
Contact your installer / electrician
Contact your installer / electrician
Contact your installer / electrician

See to the left
a. Check solar panels and DC wiring for insulation faults.
b. 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.
Check earth wiring. Make sure both earth straps are connected securely to the geyser earth stud. Wire AC to correct input (see Chapter 4 in the Installation Manual). Wire DC to correct input (see Chapter 4 in the Installation Manual).

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ID Alarm message 12 No Power on DC Input
13 DC Input Reversed

How to resolve the alarm: USERS
This can be due to several reasons: a. There is no DC power connected to the Elon Smart b. DC power is off at the DC disconnect switch close by
the Elon Smart unit. c. There is an issue with the DC wiring or solar PV
installation. d. 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: i. switching the DC power on (where applicable); ii. setting the Elon Smart heating policy to Grid Only (see Table 1.1); iii. leaving it until DC power returns; or iv. contacting your installer / electrician to inspect and fix the DC wiring and/or solar PV installation.
Contact your installer / electrician.

How to resolve the alarm: TECHNICIANS / ELECTRICIANS See to the left
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).

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ID Alarm message 14 Hot Connection

How to resolve the alarm: USERS Contact your installer / electrician.

How to resolve the alarm: TECHNICIANS / ELECTRICIANS Elon Smart not correctly inserted into geyser element. Switch off all power to the Elon Smart and re- seat (reinsert) the Elon Smart.

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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 Africa3:

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.
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You can expect the following approximate energy generation from solar modules for various locations4:

Location
Bloemfontein Cape Town Durban Johannesburg / Pretoria Mbombela Port Elizabeth Upington

Electricity generated kWh/kWp per year
2055 1762 1570 1871 1766 1698 2075

C2. Geographic features
Major geographical features (such as hills or mountains) can reduce the total solar yield.

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.

4 Urban Energy Support. Website: http://www.cityenergy.org.za/uploads/resource_274.pdf. Last accessed: 07/04/2017.
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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 roof5.
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.

5 D’Orazio M et al. 2013. Performance assessment of different roof integrated photovoltaic modules under Mediterranean Climate.
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PowerOptimal Elon® Smart User Manual Version date: 2024/08/29
Appendix D. Deciding on Size of Solar Array
Terminology used

Page 27 of 42 Version number: 1.13

Solar power is generated by solar cells, which are arranged in framed modules, typically of 60, 72, 120, 144 or 156 cells each. The total set of solar PV modules installed is referred to as a solar PV array6.

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 ­ 1.2

2 – 3 modules

1.2 ­ 1.6

3 – 4 modules

1.5 ­ 2
2.4 ­ 3.2 (two parallel PV strings)
3 ­ 4 (two parallel PV strings) * 6-minute showers at 40 °C with 8 litre/min (low-flow) showerheads

4 – 5 modules 6 – 8 modules 8 – 10 modules

6 Image source: http://ohioline.osu.edu/factsheet/AEX-652-11.
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Page 28 of 42 Version number: 1.13

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®

Location

kWh/kWp/yr

Bloemfontein

1894

Cape Town

1624

Durban

1447

Jhb/Pretoria

1724

Mbombela

1627

Port Elizabeth 1565

Upington

1912

Saldanha

1623

Annual average litres of water heated per day for X kWp installed solar capacity
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 80 99 119 139 159 179 199 249 298 348 68 85 102 119 136 154 171 213 256 299 61 76 91 106 122 137 152 190 228 266 72 91 109 127 145 163 181 226 272 317 68 85 103 120 137 154 171 214 256 299 66 82 99 115 132 148 164 205 247 288 80 100 121 141 161 181 201 251 301 352 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.

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Page 29 of 42 Version number: 1.13

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®

Location

kWh/kWp/yr

Bloemfontein 1894

Cape Town

1624

Durban

1447

Jhb/Pretoria

1724

Mbombela

1627

Port Elizabeth 1565

Upington

1912

Saldanha

1623

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

0.8 kWp 1 kWp 1.2 kWp 1.4 kWp 1.6 kWp 1.8 kWp 2 kWp 2.5 kWp 3 kWp

2.4

3.0 3.6

4.2

4.8

5.4

6.0

7.5

9.0

2.0

2.6 3.1

3.6

4.1

4.6

5.1

6.4

7.7

1.8

2.3 2.7

3.2

3.6

4.1

4.6

5.7

6.8

2.2

2.7 3.3

3.8

4.3

4.9

5.4

6.8

8.2

2.1

2.6 3.1

3.6

4.1

4.6

5.1

6.4

7.7

2.0

2.5 3.0

3.5

3.9

4.4

4.9

6.2

7.4

2.4

3.0 3.6

4.2

4.8

5.4

6.0

7.5

9.0

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.

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Page 30 of 42 Version number: 1.13

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

Bloemfontein

1894

50% 62% 75% 87% 99% 112% 124% 155%

3 kWp 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.

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Page 31 of 42 Version number: 1.13

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: 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 ­ 1.2

4

3

100 – 200

1.2 ­ 1.6

3

4 or 2

100 – 200

1.6 ­ 2

2

3

2 ­ 4
(two parallel PV strings)

4

NA

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

150 ­ 300 200+

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

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Page 32 of 42 Version number: 1.13

Appendix F. Technical Specification Summary: Elon® Smart
Refer to the PowerOptimal website for the full Technical Specification www.poweroptimal.com/specifications

Rated input voltage Rated input current Mains (AC) voltage range
System power supply Power consumption Data retention on device Solar voltage (Voc at STC) Thermostat Safety Reverse polarity protection Lightning protection Self-tests
Enclosure ingress protection rating Annual energy production compared to inverterbased system Standards conformance
Dimensions & weight Patents
Registered Designs Communications link Measurements
Data logging
Other features

230V AC, 230V DC 18A AC, 15A DC 230V +10% -15% (will disconnect all loads when breach is greater than +/- 15%) Solar PV DC or 230V AC mains 3W on either AC or DC (solar) power 2 weeks for high-resolution server data, 1 year for mobile app data 30 ­ 230 V DC Electronic thermostat with 0.5 °C accuracy Electromechanical thermal cutout For solar PV connections 8 kA Component failure, wiring failure, element failure, insulation failure, hot connections IP40

90% when solar PV array and geyser element are matched correctly
SANS 60730-1, SANS 60730-2-7, SANS 60730-2-9, SANS / EN 301 4891, SANS / EN 301 489-17, ICASA Type Approval, LoA from NRCS 23 x 12 x 11 cm, 0.3 kg ZA 2019/02129 (granted), GB2583814B (granted), ZA 2022/08516 (granted), EP 4100979 (granted), US 17/797,977 (pending), GB2206504.9 (pending) ZA F2022/00962 (granted), F2022/00963 (granted) Wi-Fi Client, Wi-Fi Hotspot (2.4 GHz) AC energy, voltage, current (5%) DC energy, voltage, current (5%) Temperature: water & ambient 15-second data retained for 14 days 5-minute data retained for 366 days Mobile app for installers and users Installation wizard with 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.
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Page 33 of 42 Version number: 1.13

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):

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:
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Page 34 of 42 Version number: 1.13

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 Lcrit (in meter)

Individual residential premises
115/Ng

Terrestrial production plant
200/Ng

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

Service / Industrial / Agricultural Buildings
450/Ng

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

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Page 35 of 42 Version number: 1.13

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 Africa7.

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

City
Cape Town Stellenbosch Worcester George Saldanha Port Elizabeth East London King Williams Town Beaufort-West Musina Britstown Durban Upington Pietermaritzburg Greytown Polokwane Bloemfontein Queenstown Vryburg Mahikeng Mbombela (Nelspruit) Kimberley Pretoria Vereeniging Welkom Johannesburg Ermelo Newcastle

Lightning strike density Ng
(strikes/km²/yr) 0.02 to 4 0.02 to 4 0.02 to 4 0.02 to 4 0.02 to 4 0.02 to 4 4 to 6 4 to 6 4 to 6 4 to 6 6 to 15 6 to 15 6 to 15 15 to 21 15 to 21 15 to 21 15 to 21 15 to 21 15 to 21 15 to 21 15 to 21 21 to 27 21 to 27 21 to 27 21 to 27 27 to 33 33 to 42 33 to 42

Lcrit (m)

Individual residential Service / industrial /

premises

agricultural buildings

29

113

29

113

29

113

29

113

29

113

29

113

19

75

19

75

19

75

19

75

8

30

8

30

8

30

5

21

5

21

5

21

5

21

5

21

5

21

5

21

5

21

4

16

4

16

4

16

4

16

3.5

13

2.5

10

2.5

10

7 Evert CR, Gijben M. 2017. Official South African Lightning Ground Flash Density Map 2006 to 2017.
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Page 36 of 42 Version number: 1.13

From Evert & Gijben (2017).
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Page 37 of 42 Version number: 1.13

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

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Page 39 of 42 Version number: 1.13

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Page 40 of 42 Version number: 1.13

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/

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Page 41 of 42 Version number: 1.13

Appendix J. Terminology

AC CoC CPA DB DC Geyser IEC Impp kWh kWp or Wp
MPP NOCT
PV SANS STC Vmpp

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.
Certificate of Compliance ­ to be issued by the electrician installing your Elon® Smart system
Consumer Protection Act No. 68 of 2008
Distribution board ­ the main electrical distribution board / panel in your home, containing circuit breakers and switches.
Direct Current ­ an electric current flowing in one direction only. Solar PV modules produce direct current electricity.
South African term for a water heater
International Electrotechnical Commission
The solar module current at maximum power point (MPP). Manufacturers usually report two Impp values: one at STC and one at NOCT.
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.
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.
Maximum power point. This is the point on a solar cell, module or array’s power or IV (current-voltage) curve that has the highest power output.
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 °C8. Since solar PV cell power output reduces with increase in temperature, a lower NOCT is better.
Photovoltaic ­ referring to the production of electric current at the junction of two materials exposed to light.
South African National Standards
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).
The solar module voltage at maximum power point (MPP). Manufacturers usually report two Vmpp values: one at STC and one at NOCT.

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

Page 42 of 42 Version number: 1.13

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References

• crses.sun.ac.za/files/research/publications/SolarGIS_GHI_South_Africa_width15cm_300dpi.png

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