POWEROPTIMAL Elon 100 Solar PV Water Heating Unit Instruction Manual

POWEROPTIMAL Elon 100 Solar PV Water Heating Unit

Product Information

The PowerOptimal product is a solar water heating system that uses solar energy to heat water in a geyser (water heater). The system includes the Elon 100 unit, which is a DC-to-AC converter that allows the solar panels to be connected to the existing geyser element, and a wiring kit for installation.

The system is designed to be installed by a trained solar PV installation technician and requires the use of insulated tools wherever applicable. Both AC and DC circuit breakers or isolators must be installed within 1.5m of the geyser (water heater), line of sight. Surge Protection Device (SPD) is only required in higher lightning strike density areas, such as parts of Gauteng and Mpumalanga, or where the DC cables are long.

The PowerOptimal product is patented with GB2583814, ZA2019/02129, and has patents pending with PCT/IB2021/050542, GB2206504.9.

Product Usage Instructions

To use the PowerOptimal product, follow these steps:

1. Refer to the PowerOptimal website for safety warnings and instructions, including manuals, training materials, and courses.
2. Gather the required tools for installation, including insulated tools.
3. Install both AC and DC circuit breakers or isolators within 1.5m of the geyser (water heater), line of sight.
4. Install Surge Protection Device (SPD) only if required in higher lightning strike density areas or where the DC cables are long.
5. Connect the Elon 100 unit to the existing geyser element using the wiring kit provided. Ensure that Surge Protection Device (SPD) is installed if required.
6. Install the solar PV array according to the guidelines provided by your solar PV module supplier or manufacturer.
7. Position and orient the array correctly for optimal power production.
8. Ground the mounting structure only.
9. Connect the array to the rest of the wiring, ensuring that both positive and negative wires are fully isolated from ground and keeping circuit breakers/isolators in the Open position.

It is critical to observe safety procedures throughout the installation process. Installers must wear a helmet and insulated safety gloves, as well as fall protection safety gear if work will be done on a roof or elevated area.

SAFETY WARNING

• Installation of the Elon® 100 should ONLY be performed by an electrical contractor registered with the Department of Labour (the so-called “wireman’s licence”) and strictly according to the installation instructions in this manual. The electrician should provide you with a Certificate of Compliance (CoC) once installation is completed.
• We strongly recommend that you use a reputable and experienced solar photovoltaic (PV) system installer to install your solar PV modules.
• 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® 100 unit or controller for any purpose.
• Use the Elon® 100 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:

Elon® 100 User Manual| www.poweroptimal.com/manuals
---|---
Training videos for electricians| www.poweroptimal.com/elon-100-training
Online User Instructions Video| www.poweroptimal.com/elon100
Online Elon® Basic Training Course| https://moolmaninstitute.com/p /elon-course

Required tools

The following tools are required for the installation. Use insulated tools wherever applicable.

• Solar modules (mounting) – please refer to solar module / mounting installation instructions –the below is only a guideline:
  • Cordless screwdriver with bits
  • Drill
  • Set of drill bits (wood, steel, stone)
  • Set of screwdrivers
  • Set of Allen (hex) keys
  • Tape measure
  • Grinder (tile roof installations)
  • Permanent marker
  • Chalk
  • Hammer
• Solar modules (Electrical):
  • AC/DC Clamp meter
  • Side-cutting pliers
  • Screwdriver set
  • Crimping tool
  • 4 mm² wire (double insulated) (or another size as determined by solar PV voltage and wire length)
  • Cable ties
• Elon® 100 – the following additional tools:
  • Drill or punch (to make holes for glands)
  • 2.5 mm² panel wire

Basic wiring diagram

• Note 1: Both AC & DC circuit breakers or isolators must be installed within 1.5m of the geyser (water heater), line of sight.
• Note 2: Surge Protection Device (SPD) only required in higher lightning strike density areas (such as parts of Gauteng and Mpumalanga), or where the DC cables are long. See Appendix F.

Note:
Surge Protection Device (SPD) only required in higher lightning strike density areas (such as parts of Gauteng and Mpumalanga), or where the DC cables are long. See Appendix F.

Note:
Surge Protection Device (SPD) only required in higher lightning strike density areas (such as parts of Gauteng and Mpumalanga), or where the DC cables are long. See Appendix F.

Solar PV array installation

Modules should only be installed by a trained solar PV installation technician. Array position and orientation have a major impact on power production (see Appendix B).

Review the instructions from your solar PV module supplier/manufacturer on installation.

Please note:
A South African standard for low voltage embedded generation installations is being developed (SANS 10142:3). In the absence of this standard, your solar PV installation technician should follow SANS 10142:1 (Standard for low voltage installations), and can refer to interim guidelines in anticipation of the SANS 10142:3 standard – see for example the document provided by PQRS:
http://pqrs.co.za/wp-content/uploads/2016/01/PV-System-Interim-Guidelines- Good-Practice-for-Solar-PV-Installations-South-Africa-.pdf.

SAPVIA (South African Photovoltaic Industry Association) has made available an excellent guide to solar PV installations. See:
https://www.pvgreencard.co.za/Solar%20PV%20Guidelines%20-%20Digital%20Spread %20High-res.pdf.

NB:
Refer to Appendices C & D for guidelines on selecting the right size solar PV array for the user requirements, and for correctly matching the solar PV array and the geyser element.

The below installation steps are a general guide only – refer to the abovementioned standards and guidelines.

1. A critical starting point is safety gear: ensure that all installers wear a helmet and insulated safety gloves, as well as fall protection safety gear if work will be done on a roof or elevated area.
2. The solar PV array should only consist of one string of 3 to 6 modules (60- or 120-cell) or 2 to 5 modules (72- or 144-cell) in series, or two parallel strings of 6 (2 x 3), 8 (2 x 4) or 10 (2 x 5) modules. Do not exceed the DC voltage or current ratings of the Elon® 100 (250V DC and 20A DC) under any circumstances. Do not exceed the maximum power rating of 4 kWp.
3. Attach bracket / mounting structure to roof. Use mounting structure recommended by solar module supplier for roof type and size of solar modules.
4. Fix the solar PV modules to the mounting structure whilst connecting the module cables to each other.
5. If practical, cover the modules to ensure that there is no potential for electric shock whilst installing the system.
6. Ground the mounting structure only.
7. Install the wiring from the solar PV array to the Elon® 100 unit in the ceiling space. Ensure circuit breakers/isolators are in the “Open” position. Installation of a Surge Protective Device (SPD) between the solar PV array and the Elon® 100 is required in high lightning strike areas, such as parts of Gauteng and Mpumalanga. See Appendix F for more information.
8. The last step is to connect the array to the rest of the wiring, making sure that both the positive and negative wires are fully isolated from the ground and keeping circuit breakers/isolators in the “Open” position.

Some “DO’s & DON’T’s” when installing solar PV arrays:
Your solar PV installer should not make any of these basic mistakes, but they are listed here just in case.

1. DO earth the PV array structure.
2. DO isolate the wires from the PV array structure.
3. DON’T use different sizes, types or specifications of modules together in the same string or array.
4. DON’T install solar arrays where they will be partially shaded during any season of the year if it can be avoided at all.
5. DO install the arrays so that there is space for inspection or maintenance when needed.
6. DO use cabling of the correct size for your solar array.
7. DON’T install the solar array flush with your rooftop. Use struts/brackets that ensure an unrestricted air gap of at least 40 mm between the roof and the modules.
8. DON’T walk on the modules.
9. DO ensure that connectors are kept clean and away from water.
10. DON’T leave exposed modules in a short circuit.
11. DO ensure that all connectors are securely fastened.
12. DON’T exceed the voltage ratings of any components.
13. DO properly route and secure all cables.
14. DON’T coil cables.

Elon 100 installation

1. Isolate the geyser – switch off the geyser circuit breaker at the main electrical distribution board (DB) AND switch off the geyser isolator at the geyser.

2. Confirm with a multimeter that there is no voltage across the wires.

3. Install circuit breaker (or isolator and fuse) for solar PV (DC) supply. Also, install an AC supply isolator/circuit breaker if there is none. NB Ensure that the DC circuit breaker is rated for the DC voltage and current of the installed solar PV array.

4. The circuit breakers/isolators must be installed within 1.5m of the geyser AND must be a line of sight / visible (i.e. do not install them at the back of the geyser).

5. The DC wires must not be earthed – i.e. they must be fully isolated from the earth. Do NOT test with a Megger.

6. Keep the DC wires as short as possible.

7. Avoid any coils in DC wires.

8. Recommended wiring size is at least 2.5 mm². Use panel wire for all connections to the Elon® 100.

9. Install the Elon® 100 unit according to the wiring diagram (see Section 2).

   • Mount the Elon® 100 unit close to the geyser and protect it from outside elements. The maximum wire length between Elon® 100 and geyser is 3 m.

   • Mount the controller (remote control) inside or next to the main DB in the house or in another convenient and accessible location (for example the garage). Double-sided mounting tape and Genkem contact adhesive work well for most surfaces. When inserting the controller wire into the Elon® 100 unit, make sure the connector clicks into place.

   • Connect the Elon® 100 and thermostat last.
     You will have been provided with either a wiring kit (Figure 4.1 – FOLLOW INSTRUCTIONS 9A) OR an element adapter (Figure 4.2 – FOLLOW INSTRUCTIONS 9B). See also the training videos on how to install either of these here: https://www.poweroptimal.com/elon-100-training/.
     9A WIRING KIT INSTRUCTIONS (follow these if you have the wiring kit as per Figure 4.1)
     Note: As per the wiring diagram, the thermostat and element should be connected to the Elon® SEPARATELY (independently).

   • For TSE and Thermowatt (RTS) thermostats, connect the connectors marked “thermostat” on the Elon® directly to the two screw terminals on the thermostat and short the two male terminals at the bottom of the thermostat together, using the bridging wire with female connectors supplied with the Elon® 100 (Figures 4.3 and 4.4). (Less than 20 mA DC current will flow through this wire – it is a sensing current only.) There must be no connection between the thermostat and the element.

   • Connect the two element terminals directly to the connectors marked “element” on the Elon®. For flange-type elements, use the supplied wiring with element connector (Figures 4.5 and 4.6). Make sure that the element connector fits tightly into the element and that the two male spade terminals of the connector are slotted correctly into the female terminals of the element. Crimp both terminals (you can do this through the plastic cover) to ensure a tight fit on both sides.

   • Slide the thermostat (with bridging wire installed) into the thermostat pocket in the element as deep as it can go. (Slide it in rotated 180 ° from its normal orientation.)

   • Continue with instructions from STEP 10.
     9B ELEMENT ADAPTER INSTRUCTIONS (follow these if you have the element adapter as per Figure 4.2)

   • Plug the thermostat into the element adapter as per Figure 4.7, ensuring a snug fit. Check that spade terminals enter female terminals correctly.

   • Plug the thermostat + element adapter into the element as per Figure 4.8, ensuring a snug fit.

   • Wire the thermostat screw terminals directly to the connectors marked “Thermostat” on the Elon.

   • Wire the element adapter directly to the connectors marked “Element” on the Elon.

   • Continue with instructions from STEP 10.

10. Set the thermostat to the desired temperature (60 °C maximum). Note that vertically installed geysers have higher temperatures at the top than the bottom (this is called thermal stratification). The temperature difference is about 3 °C per meter. Reduce the setpoint temperature in vertically installed geysers to about 5 °C lower than for a horizontally installed geyser.

11. Attach labels included with the Elon 100 (see Figure 4.9 on next page):

    • Attach “Dual Supply” labels to the AC isolator and the DC circuit breaker (or isolator).
    • Attach the “Warning – Photovoltaic Power Source” label to the DC wiring conduit in a clearly visible position.
    • Attach the “Installation Diagram” label close by the geyser in a clearly visible position – for example on a rafter. (Do not attach it directly to the geyser, as it will disappear if the geyser is replaced.)

12. Once installation is complete, do the following:

    • Turn the control dial to “SOLAR ONLY”.
    • Switch on the AC & DC circuit breakers or isolators.
    • Remove the covering from the solar modules.
    • Switch on the geyser circuit breaker at the main DB.

13. Check that the Elon® 100 unit is operational (refer to the LED lights on the controller.

    • Confirm solar PV array supply voltage and DC power to the geyser when the thermostat is closed. The Elon® 100 will switch DC power to the geyser approximately 10 to 15 seconds after DC power to the Elon® has been switched on (if there is enough sunlight). (If the thermostat is not closed, open the hot water tap in the house until the thermostat closes.)
    • Test mains power supply by turning the dial to “MAINS ONLY”. The red light should start flashing (except if the geyser is already at thermostat setpoint temperature). NOTE THAT THE ELON® WILL ONLY SWITCH TO MAINS 5 MINUTES AFTER MAINS POWER SWITCH-ON OR RECONNECTION. This is to allow grid power to stabilize after a power failure.
    • Confirm that no power is supplied to the geyser element when the thermostat is open (turn the thermostat set point to the lowest setting).
    • Set the thermostat back at the desired temperature (60 °C maximum).

14. Set the control dial to setting “2” (the 6 o’clock position). (For new property development installations, you can set the control dial to setting “1” (the 9 o’clock position). This ensures that new residents can settle in before deciding on the setting that suits their habits best.)

Note:
If doing any maintenance, rewiring or disconnecting the Elon® 100 or geyser element for any reason, it is good practice to first switch off both the AC & DC circuit breakers/isolators, and then disconnect one of the wires between the Elon® 100 and thermostat before disconnecting the rest of the wires .

Figure 4.9 Label positions (see step 10 on the previous page)

Please note: DO NOT install a separate timer on the AC side to try and regulate mains power use. Use only Elon’s control dial 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.

The Mains & Solar indicator lights indicate the following conditions: 

The control dial sets the mains & solar times as follows:

Element installation (retrofit)

If you need to exchange the element on an existing geyser, please follow the instructions provided by the element supplier. There are two main types of geyser heating elements: screw-in and flange type. There are three main types of thermostats: VKF-11, TSE and Thermowatt (the TSE and Thermowatt thermostats are quite similar). The below table provides a guide to Elon® compatibility with the different elements and thermostats.

Appendix

Appendix A. Basic Troubleshooting Guide for Electricians

NOTE:
This Troubleshooting Guide is intended for electricians and not general users. Users should please refer to the User Manual, which can be found at www.poweroptimal.com/manuals.

Things to Remember

• The red mains LED will only start functioning once stable mains voltage between 190 and 260 V AC is present for more than 4 minutes. (In other words, the Elon® will only allow mains power to the element 4 minutes after mains connection or switch-on.)
• Solar power is only recognized 40 seconds after active solar panels are connected to Elon®.
• An open thermostat (water at the correct temperature) measures between 11 and 14 V DC across the “thermostat” terminals on the Elon®. Polarity across these terminals is not important.
• A closed thermostat (cold water) measures 0 V across the “thermostat” terminals on the Elon®.
• How to switch on solar power to the element: With enough solar energy (check at solar terminals), solar power will be routed to the element within 15 seconds after the thermostat closes and the control dial is set to “SOLAR ONLY”. A green flashing LED indicates this condition.
• How to switch on mains power to the element: Turn the control dial to “MAINS ONLY” and, if the thermostat is closed, mains power will be directed to the element indicated by a red flashing LED.
• Note: Once the dial has been turned to “MAINS ONLY”, it will complete a full mains heating cycle (until the thermostat opens). Turning the control back to “SOLAR ONLY” at this point will not immediately switch the unit back to solar power. It will only switch back again after the mains heating cycle is completed (i.e. the thermostat opens) and the thermostat then closes again. You can finish the main heating cycle faster by reducing the thermostat temperature setting until the thermostat opens. Test solar power first.
• Fast flashing red/green LEDs indicate a short between a PV (photovoltaic) lead and earth – this condition prevents solar power to the element.

Troubleshooting Steps

1. Confirm correct wiring and polarity to Elon®. Also confirm test meter wires are connected correctly, black to common!
2. Confirm the correct voltages and currents of all connections through the following steps:
   • Confirm open/closed thermostat voltages (11 – 14 V DC open, 0 V DC closed).
   • Confirm controller wire is connected properly. The connections should “click” into place and appropriate LEDs should indicate (be active).
   • With solar power to the element switched on (green LED flashing), confirm the same DC voltage to the element as measured at solar terminals.
   • With DC clamp meter confirm that there is an active current through the element.
   • With mains power to the element switched on (red LED flashing), confirm the same AC voltage to the element as measured at mains terminals (should be approx. 230V AC).
   • With AC clamp meter confirms active current through the element of between 9 and 18 Amps depending on the element rating.
3. If you used a test controller for troubleshooting, remember to plug the wire from the installed controller back into the Elon® and check to function. Set the thermostat back to the original setting.

Appendix B. 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)

B1. Solar irradiance levels
The map below shows the general solar irradiance levels (GHI or Global Horizontal Irradiance) in South Africa1:

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.

You can expect the following approximate energy generation from solar modules for various locations2:

Location| Electricity generated

kWh/kWp per year

---|---
Bloemfontein| 2055
Cape Town| 1762
Durban| 1570
Johannesburg / Pretoria| 1871
Mbombela| 1766
Port Elizabeth| 1698
Upington| 2075

B2. Geographic features
Major geographical features (such as hills or mountains) can reduce the total solar yield.

B3. 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.

B4. 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 & 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.)

B5. 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 cause 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).

B6. 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 roof3.

B7. 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 C. Deciding on Size of Solar Array

Terminology used

Solar power is generated by solar cells, which are arranged in framed modules, typically of 60 or 72 cells each. The total set of solar PV modules installed is referred to as a solar PV array4.

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

TABLE C1. 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 kW p installed solar capacity
---|---|---
Location| kWh/kW p /yr| 0.8 kW p| 1 kW p| 1.2 kW p| 1.4 kW p| 1.6 kW p| 1.8 kW p| 2 kW p| 2.5 kW p| 3 kW p| 3.5 kW p
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.

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 kW p installed solar capacity

Location **kWh/kW p /yr ****0.8 kW p ****1 kW p ****1.2 kW p 1.4 kW p 1.6 kW p 1.8 kW p 2 kW p 2.5 kW p 3 kW p 3.5 kW p**

Bloemfontein| 1894| 2.4| 3.0| 3.6| 4.2| 4.8| 5.4| 6.0| 7.5| 9.0| 10.4
Cape Town| 1624| 2.0| 2.6| 3.1| 3.6| 4.1| 4.6| 5.1| 6.4| 7.7| 9.0
Durban| 1447| 1.8| 2.3| 2.7| 3.2| 3.6| 4.1| 4.6| 5.7| 6.8| 8.0
Jhb/Pretoria| 1724| 2.2| 2.7| 3.3| 3.8| 4.3| 4.9| 5.4| 6.8| 8.2| 9.5
Mbombela| 1627| 2.1| 2.6| 3.1| 3.6| 4.1| 4.6| 5.1| 6.4| 7.7| 9.0
Port Elizabeth| 1565| 2.0| 2.5| 3.0| 3.5| 3.9| 4.4| 4.9| 6.2| 7.4| 8.6
Upington| 1912| 2.4| 3.0| 3.6| 4.2| 4.8| 5.4| 6.0| 7.5| 9.0| 10.5
Saldanha| 1623| 2.0| 2.6| 3.1| 3.6| 4.1| 4.6| 5.1| 6.4| 7.7| 9.0

The table is based on 6-minute showers at 40 °C and 8 liters/min low-flow showerheads. Old showerheads can use up to 15 liters/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 C3. 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 liters 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 kW p installed solar capacity
---|---|---
Location| kWh/kWp/yr| 0.8 kW p| 1 kW p| 1.2 kW p| 1.4 kW p| 1.6 kW p| 1.8 kW p| 2 kW p| 2.5 kW p| 3 kW p| 3.5 kW p
Bloemfontein| 1894| 50%| 62%| 75%| 87%| 99%| 112%| 124%| 155%| 187%| 218%
Cape Town| 1624| 43%| 53%| 64%| 75%| 85%| 96%| 107%| 133%| 160%| 187%
Durban| 1447| 38%| 47%| 57%| 66%| 76%| 85%| 95%| 119%| 142%| 166%
Jhb/Pretoria| 1724| 45%| 57%| 68%| 79%| 91%| 102%| 113%| 142%| 170%| 198%
Nelspruit| 1627| 43%| 53%| 64%| 75%| 85%| 96%| 107%| 134%| 160%| 187%
Port Elizabeth| 1565| 41%| 51%| 62%| 72%| 82%| 92%| 103%| 128%| 154%| 180%
Upington| 1912| 50%| 63%| 75%| 88%| 100%| 113%| 126%| 157%| 188%| 220%
Saldanha| 1623| 43%| 53%| 64%| 75%| 85%| 96%| 107%| 133%| 160%| 186%

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.

TABLE C4. PEAK POWER OUTPUT FOR VARIOUS SOLAR MODULES AND ARRAY SIZES
The peak power production (Wp) of the modules at STC (Standard Test Conditions) and at NOCT (Nominal Operating Cell Temperature) are provided by the solar PV module manufacturer. The below table indicates the peak power at STC for a range of solar module power ratings and array sizes.

Examples:
An array of 4 x 325 Wp modules in series will have a total peak power (at STC) of 1.3 kWp.

An array of 2 parallel strings of 5 modules of 280 Wp each (10 modules of 280 Wp in total) will have a total peak power (at STC) of 2.8 kWp.

Appendix D. 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 D1. GUIDE: PV ARRAY AND GEYSER (WATER HEATER) ELEMENT MATCHING

__

Solar PV array size (kW p )

| Best matching geyser element size (kW)| *2 nd 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| 150 – 300
2 – 4 (two parallel PV strings)| 4| NA| 200+

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 < 20A
• Voc < 240V
• Power < 4 kWp

Appendix E. Technical Specification Summary: Elon® 100
Refer to the PowerOptimal website for the full Technical Specifications at www.poweroptimal.com/specifications.

when breach is greater

than +/- 15%)

System power supply| Solar or 230V AC mains
Power consumption| <3W on mains power; <0.5W on solar power
Shutdown| Sufficient power supply capacity to manage processor, switching and

data storage if both mains and solar supply fail

Solar voltage (V oc at STC)| 20 – 250 V DC
Solar energy availability| Automatically determines availability of sufficient solar energy

before supplying load from solar modules

Controller settings| Can be adjusted to run from “solar only” (100% solar energy use) to

“mains only” (no solar energy use)

Thermostat| Uses the standard normally open thermostat switch associated with the geyser element as a sensor only, with less than 10mA sense

current, to control power to the element

Reverse polarity protection| Protected against reverse connection of solar array
Enclosure ingress

protection rating

| IP65
Maximum distance Elon®

unit to controller

| 10 m
Annual energy production compared to inverter-

based system

| > 90% when solar array and geyser element are matched correctly
Standards conformance| IEC / SANS 60669, CISPR 11 & IEC 61000-6-1
Dimensions & weight| Elon® 100 main unit: 200 x 150 x 60 mm (LxWxH), 1.75 kg. Controller:

50 x 72 x 41 mm (LxWxH)

Patents| ZA          2019/02129           (pending),         GB2583814A (granted),

PCT/IB2021/050542 (pending)

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

Appendix F. 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® 100.

The draft standard “SANS 10142-3: Proposed Interim Guideline for the wiring of LV grid-embedded PV installations not exceeding 1000kVA in South Africa” requires a Surge Protection Device to be installed where the length (L) of the DC cables (from PV array to Elon® 100 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® 100, distance L is the length of DC cables from PV array to the Elon® 100. On the next page is a national lightning ground stroke density map for South Africa5.

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
Port Elizabeth| 0.02 to 4| 29| 113
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
Durban| 6 to 15| 8| 30

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

City

| Lightning strike density Ng (strikes/km²/yr)| Lcrit (m)
---|---|---
Individual residential

premises

| Service / industrial /

agricultural buildings

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

Appendix G. IEC/SANS and EMC Test Certificates: Elon® 100

Appendix H.

Warranty

If the PowerOptimal Elon® 100 (“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. 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.

Appendix I. 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® 100 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 °C6. Since solar PV cell power output reduces with an increase in temperature, a lower NOCT is better.

• PV
  Photovoltaic – refers 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.

© PowerOptimal (Pty) Ltd 2022. 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.

References

• crses.sun.ac.za/files/research/publications/SolarGIS_GHI_South_Africa_width15cm_300dpi.png
• PowerOptimal Elon® 100 training videos for electricians (7:26) - PowerOptimal - the Future of Energy
• PowerOptimal Elon® 100 user instructions video (8:13) - PowerOptimal - the Future of Energy
• Product Specifications - PowerOptimal - the Future of Energy
• PowerOptimal Elon® Solar PV Water Heater Basic Training Course | The
• Installation & User Manuals - PowerOptimal - the Future of Energy
• PowerOptimal Elon® 100 training videos for electricians (7:26) - PowerOptimal - the Future of Energy

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