FAQ

Some answers to frequently asked questions:

Q. What is the GT+ Smart?

A. The GT+ Smart is the Pi2R iX unit coupled with the optional digital touchscreen display to give it additional “Smart” functionality. The GT+Smart is available in two versions, one with WiFi and one without. The Pi2R iX on its own is sometimes referred to as the “Lite”.

Q. Can I connect more than one geyser to a geyser solar unit?

A. Yes, but only the Pi2R iX unit and then only provided that the maximum total power consumption of the elements is 4kW, i.e. 2 x 2kW elements are used. 

Q. How many panels can one connect to a Pi2R iX?

A. One has to consider both the voltage input range of 90 - 350Vdc (the iX can handle 350Vmp whilst the element’s maximum is 320Voc) and the maximum amperage that the unit would be capable of delivering, which is 15A. Bearing these two parameters in mind, if one connected, for example, 4 x 550Wp panels with a Vmp (voltage @ maximum power) of 41V and output of 14A, this would give a total Vmp of 164 Volts and a max output of 14A, which would be appropriate. 
We have, however, found that 3 of these panels works well. Provided that one stays within the voltage range, the number of panels chosen depends on how quickly one would want the water to be heated.

Q. How many panels should I pair with the GeyserTech MICRO unit?

A. There are two parameters to consider here. The first is the PV input voltage of the MPPT controller on the MICRO unit. The range is 90 to 200Vmp (maximum power voltage) so the minimum input would be 90V. If, for example, one used standard panels which could deliver 41Vmp each, three panels would add up to 123Vmp combined, which is in range. Another very cost effective option is to use 2 x high voltage panels which typically produce around 82Vmp each. These would give a total voltage of around 164Vmp. 

Try to avoid using panels at the bottom end of the voltage range as one may find the MPPT controller switching on and off continuously in low light conditions. One normally would look at aiming for mid range, i.e.around 150Vmp. 

The second consideration is the amperage capability of the controller on the MICRO which is 7.5 amps, meaning that anything produced above that would not be used (the higher wattage panels can produce up to 14 amps). This means that one could go for a lower wattage panel with the same results. The advantage of a more powerful panel, however, would be better performance under low light conditions.
A High Voltage panel produces less amps than a standard voltage panel of the same wattage (Watts = Volts x Amps). This, however, is appropriate for the Micro controller as it can only utilise up to 7.5A anyway.
 
(The same principles would apply to an installation with the iX controller, but the allowable maximum voltage range would be higher in accordance with the iX’s specifications)

 

Q. What is the difference between a High Voltage (HV) solar panel and a standard voltage solar panel?

A. To derive the power output capability of a solar panel, the relationship between the voltage the panel produces and the amperage it is capable of delivering is measured in Watts (Wp) and determined by the formula: Watts = Volts x Amps. 

Therefore, for example, a 450Wp panel can be one that produces 45V and 10A as one would expect from a standard voltage panel. However, one could also have a 450Wp panel which, for example, produces 90V and 5A (these panels are known as High Voltage panels).

The advantage a High Voltage panel offers is particularly relevant to the Pi2R Micro controller as it has built-in circuitry which limits the amount of amps that it can draw to 7.5A. Using a HV panel with the Micro means that none of the available PV power is lost, whereas any amps in excess of 7.5A produced by a standard voltage panel would not be used.

Q. What do the colours of the INDICATOR LED mean?

A. 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 10 minutes.
  • Flashing Green: This indicates that solar power is available, but the geyser temperature is currently at the temperature that the thermostat is set to and the thermostat has switched off.
  • Solid Green: Solar power is currently feeding into the geyser.
  • Flashing Red: This indicates that AC power is available, but the geyser thermostat has switched off.
  • Solid Red: AC power is currently feeding into the geyser.

 Q. Which source of power has priority?

A. When AC power is made available to the unit, it will be fed to the geyser in preference to solar. For this reason it is necessary to limit the time that AC is fed to the unit so as to achieve the desired energy savings. This can be achieved by installing a geyser timer on the AC side or (applicable to the Pi2R iX only) by installing the optional Digital Touchscreen Display. When AC is not made available, solar PV power will be fed to the unit whenever it is produced at sufficient voltage.

Q. Can the Geysertech Pi2R controllers be used off-grid?

A. Yes, both the Pi2R Micro and Pi2R iX can be used entirely off-grid.

(when wanting to use the Digital Display off-grid, please contact us to arrange for a long-life battery for the screen)

Q. Can the units feed back into the grid?

A. No. Due to the internal circuitry of the unit, it cannot feed back into the grid.

Q.  Do the units feed DC to the element?

A. No, power is fed to the element as a modified wave which varies in voltage according to output from the solar panels. This is safe to use on a resistive type element.