Western Co WRM20 Benutzerhandbuch Seite 15

General description
WRM20 is a photovoltaic charge regulator for electrochemical batteries either sealed (SEAL) or flooded lead acid
(FLOOD) and for lithium-ion or LiFePO4 batteries with integrated BMS (Battery Management System). We suggest to
contact Western CO. Company for the selection of lithium battery that you can combine with WRM20. It is absolutely
forbidden to connect to WRM20 lithium-ion battery without an integrated BMS because its function is to protect the
battery from unsafe operating condition that can cause the burn up of the battery.
In Pic.1 there is a WRM20 working principle scheme.
1- Recharge circuit: it adapts Vpan and Ipan (respectively voltage and current of the photovoltaic module) so to reach
the condition in which the power that is given by the PV module is maximum, thus realizing the MPPT (Maximum
Power Point Tracking). In addition, it manages the battery recharge by reducing the current sent towards the battery
when the voltage Vbatt exceeds its recharge voltage (Veoc).
2- Series diode: its function is to avoid that during the night, when the PV module is not lighted up, it can absorb
current from the battery.
3- Circuit for the load control: it turns on/off the load according to the program that has been set from the user and it
provides to the load detachment in case of low battery / overload / short-circuit on the load. Load voltage is the
same as battery voltage.
4- Microprocessor: it controls the whole circuit, it measures currents and voltages of PV module / battery / load and it
shows them on the display.
Choice of the PV module
WRM20 charge regulator, thanks to the MPPT recharge circuit, allows to use a wide range of PV modules ensuring the
optimum use of the whole power. The PV module has to be chosen according to the nominal voltage of battery and
respecting the constraints of the panel input of WRM20: maximum voltage 100V and maximum panel power 310W with
battery at 12V and 620W with battery at 24V.
Battery nominal voltage
12V Battery nominal voltage
24V Battery nominal voltage
WRM20 and WRM20+
User manual
Pic.1 Schematic
I
PAN
V
PAN
V V
mp OC
Features of PV modules
V : voltage at the maximum power at T=25°C > 15,0V
mp
V : open circuit voltage at T=-10°C <100V
OC
P : maximum power at 25°C <310W
MAX
We recommend PV modules with mono or polycrystalline silicon
with a number of cells from minimum 36 to maximum 144 cells.
V : voltage at the maximum power at T=25°C > 30,0V
mp
V : open circuit voltage at T=-10°C <100V
OC
P : maximum power at 25°C < 620W
MAX
We recommend PV modules with mono or polycrystalline silicon
with a number of cells from minimum 72 to maximum 144 cells.
3
EN