Overview PV Domestic Hot Water 2



With this function block a PV surplus can be used for domestic hot water heating.


Inputs

BA
 Operating mode*
 Operating mode:
  • 0=Automatic
  • 1=On
  • 2=Off
MA
 Manual button
 On a rising edge the hot water is heated once to the setpoint. After the setpoint is reached the input switches back to 0 if an address has been connected, so that the address can be connected to a button that switches itself off again automatically. On a falling edge the heating is interrupted again.
PU Surplus* PV surplus.
IW
 Actual value*
 Actual hot water temperature
SP Setpoint PV* Hot water setpoint in automatic mode
SM Setpoint grid* Setpoint when hot water is generated without PV surplus (manual on or 1x heating)
FG Enable Optional enable. If this input is not connected, the control is always enabled, otherwise only when the input is 1. This input can be used when another consumer should have priority without having to switch the operating mode.
SE Setpoint continuous on % Optional setpoint when operating mode On or 1x heating is active. If this input is not connected, 100% is always output.
TM Minimum temperature Optional minimum temperature. If the value is greater than 0, it is evaluated as the minimum temperature with a hysteresis of 1 degree. If the actual temperature drops below this value, the hot water is kept at this temperature with grid power as well, independently of the PV surplus and independently of the operating mode. The heating switches off again as soon as the actual temperature exceeds the minimum value by 1 degree. The input Setpoint continuous on % is used as the setpoint in percent (100% if not connected). If the input is not connected or 0, the function is disabled.

Outputs
SW
 Setpoint percent
 Setpoint 0-100%
MA Manual active Info 1x heating manually active
RA PV control active Output is 1 when the control is active or the time from the parameter Surplus minimum time is reached.

Parameters

Hysteresis
 Hysteresis for the setpoint/actual value comparison. The hysteresis acts in the negative direction, that means when the actual value is lower than the setpoint minus hysteresis the heating is switched on, and when the actual value exceeds the setpoint the heating is switched off.

Gain
 Speed of the control; with a higher value the output reacts faster to a change at the input. A value of 0.4 is recommended for the input in kW.

Surplus minimum Minimum surplus that must at least be present so that the control starts. If the feed-in falls below this surplus the control automatically reduces; a surplus should therefore always be specified so that the control reduces early.

Surplus [kW] when PU
  • Positive, surplus is present when the value at the PU input is positive.
  • Negative, surplus is present when the value at the PU input is negative.

Surplus minimum time Time during which the PV surplus must be present so that the control starts. This can ensure that PV surplus is reliably present, for example so that the control does not constantly start/stop during cloud breaks or load changes.

See also common parameters of all function blocks.