PowerOptimal Elon® Smart thermostat specification V1.15
INTRODUCING THE
PowerOptimal Elon® Smart Thermostat
The Elon Smart Thermostat transforms standard electric geysers into smart, solar PV-ready green appliances. Android & iOS apps allow monitoring and management with your smartphone, including water temperature and grid & solar energy use. Real-time monitoring and communication deliver actionable data. Early alerts for leak detection, element failure and other geyser faults reduce cost, damage and inconvenience. Simple installation with plug- and-play solar PV enables cost savings and reduced reliability on fossil fuels, improving quality of life.
Document
Version: 1.15
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
Data retention on device
2 weeks for high-resolution server data, 1 year for mobile app data
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 connection
Enclosure ingress protection rating
IP40
Radiated immunity
IEC 61000-4-3 Level 3, 10 V/m
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: ZA2019/02129, GB2583814B, ZA2022/08516, EP 4100979, US 12,122,914, GB2618349, ZA2024/08399, EP4519612
Pending: PCT/ZA2024/050065, CN2023800381161, US 18/861,142, AU2023265634, ZA2023/11726, ZA2024/08845, PCT/ZA2025/050066
Registered Designs
ZA F2022/00962, F2022/00963
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
Cloud backend for remote monitoring & alerts
Estimation of water use
Advanced features scheduled for externalpremium app availability in H2 2026
Leak detection (software-based)
Anode condition monitoring
It is important to match the solar PV array and heating elements for maximum power transfer efficiency. Refer to the table below for the recommended AC heating element power rating for different solar panel specifications and configurations.
TABLE 1. 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 – 1.6
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
Contact PowerOptimal for advice on module-element matching if module properties are significantly different to typical values or for bifacial, high current or high voltage modules.