HOW YOUR WATER HEATER WORKS
8
The Solahart PowerStore has inbuilt protection against running low on hot water and will also maintain a fixed
minimum water temperature as a safety and compliance requirement. During periods when there is no excess
power from solar PV generation and heating of the water is required, electricity from the utility grid will be used
to ensure the availability of hot water.
Note:
If the water heater tank is installed without either the external control device or connection to a home
energy management system (HEMS), it will operate as a conventional twin element electric water heater. It
w
on’t be able to take advantage of excess solar PV power production or be part of an intelligent water heating
system.
TWIN ELEMENT OPERATION
This water heater has two multi-stage triple blade variable power input heating units, each controlled by the
temperature sensors and the control system. One heating unit is near the top of the water heater and the other
at the base. The two heating units are wired for non-simultaneous operation, so only one heating unit can
operate at a time.
Top heating unit
The top heating unit has priority under normal operation to heat the water in the top portion of the tank.
When there is less than 90 litres of hot water in the tank, the top heating
unit will energise to heat the top 150 litres to 60°C using utility grid
supplied electricity and if available, also take advantage of excess solar
PV power generation.
The top 150 litres of water will then be heated to 75°C during periods of
excess solar PV power generation only, without additional utility grid
sourced electricity supply *. Heating then switches to the bottom heating
unit.
(* A minor amount of grid energy may be used as the PowerStore control system
tracks available excess solar PV production. This is normal operation.)
Bottom heating unit
The bottom heating unit is activated under normal operation after the
top heating unit has heated the water in the top portion of the tank to
75°C.
The bottom heating unit heats the water in the lower portion of the tank
to a maximum temperature of 75°C during periods of excess solar PV
power generation only, without additional utility grid sourced electricity
supply.
Note:
AS 3498 requires that a water heater provides the means to
inhibit the growth of Legionella bacteria in potable water. This
requirement is met if at least 90% of the stored water is heated to 60°C
once every seven days. If this does not occur during normal operation,
the water heater will enter Safety Compliance mode and use utility grid
sourced electricity to satisfy this requirement with heating via the bottom
heating unit.
Electrical connection
The utility grid sourced power supply to the water heater must be a 24 hour Continuous / Domestic Time
of Use type. A separately metered controlled load supply, i.e. Off-Peak / time controlled, is not suitable.
NOTE: Power must be available to the heating units
’ circuit at all times for this water heater to operate
as designed.
