Below you’ll find answers to the most common questions about the Elon 100 and Elon Smart solar PV water heating systems — covering installation, performance, compliance, and compatibility.
1. System & Technology
How can solar PV water heating be more cost-effective than solar thermal?
Although solar thermal collectors are more efficient per square meter, overall cost-effectiveness depends on lifetime, maintenance, and heat losses.
Solar thermal systems have a typical lifespan of 7–15 years.
Solar PV modules are guaranteed for 25+ years with minimal maintenance.
PV costs have dropped by over 80% in 5 years, making them more cost-effective despite lower conversion efficiency.
What is kWh?
A kilowatt-hour (kWh) is a unit of energy.
1 kWh = 1 kW of power used for 1 hour.
Examples: A 3 kW geyser element consumes 3 kWh in one hour. A 10W LED light consumes 1 kWh in 100 hours (0.01 kW x 100h = 1 kWh)
2. Product Information
Does the Elon 100 work with geyser brands other than Kwikot?
✅ Yes. It works with any standard electric geyser with TSE or VKF-11 thermostats.
Does the Elon Smart work with geyser brands other than Kwikot?
❌ No. It is designed specifically for Kwikot geysers.
Does the Elon have a MPPT?
No. The Elon uses direct DC heating. Efficiency loss is typically < 10%, and it works in lower light where MPPT systems might not.
Can I install the Elon 100 or Elon Smart in series with a MPPT?
No — MPPT should never be installed in series with an Elon.
Is the Elon Smart compatible with Xtend PTC elements?
No — not currently.
3. Installation & Setup
Do I need to change the heating element on my existing geyser?
Not necessarily. The Elon works with existing elements, but element size should match your solar PV array. Refer to the Installation Manual or ask your installer.
How many solar modules do I need?
Minimum: 1 kWp.
Maximum (at Standard Test Conditions or STC):
Elon 100: 4 kWp (Isc < 20A DC, Voc < 250V DC)
Elon Smart: 3 kWp (Isc < 15A DC, Voc < 230V DC)
Note: since most solar PV modules these days have short-circuit currents (Isc) of more than 10A DC, parallel strings will in most cases exceed the maximum short circuit current specification of the Elon 100 and Elon Smart.
Does the Elon require installation of an earth spike?
No. It uses the existing TN earthing system. An earth spike is only needed if the house has no municipal supply.
Are Elon solar PV installations grid-tied or off-grid?
They are off-grid — the Elon has a double-pole, double-throw, break-before-make changeover relay that switches power supply to the element between solar PV (DC) and grid (AC). That means that it is impossible for DC power to flow into the AC supply or for AC power to flow into the DC supply. Hence, the Elon qualifies as ‘off-grid’ for solar PV installations.
How does the Elon 100 know what time it is?
It uses solar noon detection via the PV modules to calibrate its internal timer automatically.
Does the Elon 100 work with geysers with VKF-11 thermostats?
Yes — but follow the wiring instructions in the Installation Manual carefully to separate the thermostat and element connections.
4. Operation & Performance
How do loadshedding & power surges affect my Elon system?
Loadshedding: Continues on solar PV if sun is available.
Power surges: Both models have surge protection. For lightning-prone areas, add an SPD.
What is the most cost-effective water heating option in South Africa?
When considering all costs (including upfront costs, operating costs, maintenance costs and system lifetime) - in other words the Levelized Cost of Energy (LCOE), the Elon® offers the lowest lifetime cost vs. grid, solar thermal, gas, or heat pump systems.
What is the payback period for an Elon® system?
Typically 2–4.5 years, depending on tariff, number of modules, and usage. After that, you enjoy ~25 years of low or no cost hot water.
5. Warranty, Compliance & Training
Where can I register for the extended 5-year warranty on my Elon unit?
What is SANS 10400-XA?
South African energy efficiency regulation requiring that no more than 50% of annual hot water be heated using grid power. Elon® helps meet this requirement easily.
Do I need to apply for approval from my municipality?
Most municipalities require registration, not approval.
City of Cape Town requires approval via e-Services, but no engineer sign-off for solar PV water heaters.
Where can I get training on installing the Elon 100 or Elon Smart?
Installations must be commissioned by a registered electrician with a Supplementary CoC (when PV is used).
PowerOptimal offers in-person and online training. PV-Greencard installers are recommended.
6. Inverters & Advanced Use
Can I connect my inverter AC output to the Elon Smart AC input?
Yes — but:
Geyser will draw full power (e.g. 3–4 kW).
You need a larger inverter (at least 8 kW) and you should avoid using other high-power appliances at the same time.
A 3 or 4 kW power draw can drain your batteries quickly. Hence, you only want to use inverter geyser heating in the early to mid-afternoon (around 12:30 to 15:00), when batteries are typically fully charged and the solar PV output is high.
Use the custom timer settings in the Elon Smart app to set this up.
Don’t insert a separate timer between the inverter and the Elon Smart.
7. More Information
Where can I learn more about the PowerOptimal Elon®?
Visit the PowerOptimal website, check the Case Studies and Downloads.