Solar & Solar Geysers

Off-grid capable

Low cost & compact

  • Launched in June 2022
  • We have produced and installed more than 500 of these units during the first year.
  • Most of these units are installed in 100% off-grid installations.

The Wise Geyser Nano Pi²R (micro) is simplistic yet still delivers great power savings and makes your geyser wise. Our first module with integrated MPPT specifically targets small household retrofit electrical geysers. No need to change the geyser element or existing thermostat. (Maintaining your geyser warrantee) No external components needed (A DB timer can be added as an optional automation method).

DB Timer optional for automation

The Wise Geyser Nano Pi²R (Micro) uses any existing 50-150 Litter geyser as is. Larger geysers can be used as long as the element is changed to a 2kW or 3kW element. Power is fed to the geyser and temperature is still controlled by the standard thermostat. A simple external DB timer fully automates the operation of the Wise Geyser Nano Pi²R (Micro) making your geyser wise. The timer enables/disables AC power on the times required by the user. When Grid is not available Solar is forced, thus enabling easy to understand setup.

Indicator LED

There is a small indicator LED showing one of 7 states:

Off: No power is connected
Alternating Red/Green: Over temperature state, normal operation will resume once the internal controller has cooled sufficiently.

Fast flashing Green: This indicates that the MPPT is synchronizing, should happen about every 10min.
Flashing Green: This indicates that solar power is available, but the geyser is currently warm enough so that the thermostat is switched off.
Solid Green: Solar power is currently feeding into the geyser.

Flashing Red: This indicates that the AC power is available but the geyser thermostat is switched off.
Solid Red: AC power is currently feeding into the geyser.


  • Up to 200Vmp photovoltaic (PV) solar input (Maximum Power Voltage)
  • Constant voltage MPPT engine
  • Minimum external components
  • Excellent for off-grid
  • Easy to override
  • Excellent durability
  • Low cost
  • SANS Compliant
  • Top seller
Technical Specifications
Element Size 2,3 kW
Grid input 200 – 240Vac
PV MPPT Yes, 7.5 Amp
PV input 90 – 200Vdc
*Do not exceed 240Voc
Max PV Power 1,500 Watt
Dimensions 100 * 180 * 80mm
Operating Temperature -10 – 55° Celsius
Safety & Protection
AC Disconnect Yes
Over Temperature cut-out Yes, 65° (+- 5°)
Reverse Polarity Yes
Requires external fuse
Transient Category 1 3-Way Surge Arrester
EMC Compliant EN-61326-1

Frequently asked questions

  • Does the Nano feed the element with DC?

No. The modified wave is safe to control with the existing thermostat.

  • What is the maximum power I can connect to the Nano?

The important part is to stay below 200Vmp (240Voc) input, and only 3kW element maximum. 150Vmp with a 3kW element is the recommended Maximum. If too much Amps are available, the Wise Geyser Nano Pi2r (micro) will limit itself to avoid damage. Now that’s being Geyser Wise for you.

  • Why not use 30-40V?

Because we feed the standard 230V element, we need a bit higher voltage than our competitors where they mostly use dedicated low voltage DC elements, we make use of the standard geyser element.

  • What power throughput can I expect with lower voltage input?

The math behind power throughput can be expressed as:

Power = Volts²/Resistance

The below calculator shows what the maximum power throughput will be with different voltages and element sizes.
Note: photovoltaic (PV) Amps are not considered in the following calculator as it will not affect the maximum throughput.
However, if the photovoltaic (PV) panels can output more than the “Current draw” of the calculator, the MPPT will not be able to utilize all of the available power.

Voltage:Volt Element:kW

Output power = 1125 Watt

Current draw = 7.5 Amp

Power will not be limited.

  • Can I connect panels with more than 7.5A output?

Yes. The Wise Geyser Nano Pi2r (micro) measures the input current and will limit itself to not draw too much amps, ultimately making this geyser wise with this technology added to it.

  • My panels are capable of 10A, why is the Nano not using all of it?

Firstly, the element only draws what it wants on a certain voltage. See power throughput formula. Secondly, the Wise Geyser Nano pi2r (Micro) limits itself to draw only 7.5A as not to damage its internal components. Now that’s being Geyser Wise for you.

Technical specifications

Electrical Specifications

Wise Geyser Nano – Max (Micro) (iX)

Element Size 2 – 3 kW 2 – 4 kW

AC Input

Voltage 220 – 240 Vac

Frequency 50 Hz ± 10%

Internal current limiter N/A 20A Fuse

DC Input

Voltage 90 – 200 Vdc 90 – 325 Vdc

MPP 120 – 200 Vdc 120 – 325 Vdc

Internal current limiter 7 Amp 14 Amp

General Data

Dimensions (W/L/H) 180 * 100 * 45mm 180 * 125 * 45mm

Weight 560g 750g

Operating Temperature -10°C – +50°C

Noise emission, typical 20dB(A)

Cooling method Passive/Convection

Self-consumption 0.5 Watt 1.0 Watt

Degree of protection




EMC IEC 61326-1

Safety IEC 60730-1

NRCS Pending (SR #1-115237307)