Solar Pump Control

The solar pump will switch on if the following condition is true:

where

delta Ton = SOLP-01 + (20 - FilteredOATemp) * (SOLP-03 - SOLP-01)/ 35

whereas FilteredOATemp is the filtered outside air temperature.


If SOLP-03 >= SOLP-01, the temperature difference at low temperatures is higher than the difference at higher temperatures.

When the filtered outdoor temperature > 20°C or SOLP3 = SOLP1, delta Ton is equal to SOLP-01.

For a correct solar panel operation, the following setting limitations are automatically controlled and overridden by the solar control:

If the user enters a value for:


The next two figures show the solar pump control for a switching pump and a variable speed pump depending on the temperature difference between solar panel temperature and the DHW lower temperature.

CalcTempDiff = SolPanelTemp – DHWLowerTemp

Both pump output signals are available at the same time regardless of the setting of parameter CFG-02: solar pump configuration. This parameter value is important only for the solar power management.

Fig. 2.   Solar pump command for switching pumps and speed control for variable speed pumps

Table 2.   Parameter List

Description

Value Range

Default Value

Unit

CFG-02: solar pump configuration

1 = on/ off pump

2 = variable speed pump

1/ 2

1

-

SOLP-01: temperature difference to switch on at OAT >= 20 °C

-30 … 30

6

K

SOLP-02: temperature difference to switch off/ over

-30 … 30

3

K

SOLP-03: temperature difference to switch on when the OAT = -15 °C

-30 … 30

6

K

PMP-03: pump minimum off time

0…120

20

sec