Schneider Electric Owner's Guide

Introduction
1–4 975-0560-01-01 G
Charge Controlling
The charge controller regulates the PV array current at an appropriate level for
24 or 48 V batteries. It can produce up to 80 amps of charging current for both
2560 watts at 24 V or 4800 watts at 48 V.
The charge controller can be configured to use a two-stage (no float) or three-
stage charging algorithm. The charging algorithm assures that the battery is
optimally charged with the available amount of solar energy. See the Conext
MPPT 80 600 Solar Charge Controller Installation Guide for more information on
two-stage and three-stage charging as well as the different stages.
Three-Stage Battery Charging
The three-stage battery charging process results in more efficient charging
compared to on-off relay type or constant voltage solid-state regulators. The final
float stage reduces battery gassing, minimizes electrolyte loss, and ensures
complete battery recharging. Battery voltage and current vary during the
three-stage charging process as shown in Figure 1-2 on page 1–5.
Bulk Stage
During the bulk stage, the charge controller operates in constant current mode,
delivering the maximum current to the batteries (the maximum current depends
on the available solar energy). Once the battery voltage reaches the absorption
voltage setting, the charge controller transitions to the absorption stage.
Absorption Stage
During the absorption stage, the charge controller operates in constant voltage
mode and the charging current falls gradually as the amp hours are returned to
the battery. The voltage limit used for the first 60 minutes of this stage is the bulk
voltage setting. The voltage limit used for the remaining time in this stage is the
absorption voltage setting. The default settings make the bulk voltage setting
and the absorption voltage setting the same for all battery types.
The default voltage limit settings (bulk and absorption) can be adjusted if the
battery type is set to Custom (see “Setting a Custom Battery Type” on page 2–7).
For flooded lead acid batteries only, you can use a custom charging scheme
which sets the bulk voltage higher than the absorption voltage. The result of this
is a boost voltage charge level that has been found to be beneficial for ensuring
enough amp hours are returned to the battery bank for off-grid installations. For
detailed information on how boost charging works and when it is recommended,
see Appendix C, “Boost Charging”.
975-0560-01-01(XW-MPPT80-600_Ops).book Page 4 Wednesday, November 22, 2017 5:52 PM