The System Design
System Design is the process of defining the architecture, components, modules, interfaces and load data for a system to
satisfy specified requirements.
For a solar energy system, these components are the PV modules, inverter/charge controller & batteries, as well as the
different interfaces of those components.
Battery Operation
There are several factors that affect the operation of the battery that could impact its ability to deliver capacity and life
expectancy.
Storage
Battery Module shall be stored in original packaging, in a clean, level, dry, cool location indoors.
Recommended storage temperature is 77°F (25°C).
The battery can be stored in the range of -4°F to +113°F (-20°C to +45°C) but it requires an inspection and recharge every
three months (max charging current is 0.1C).
Max SoC storage % is 50%.
Max Transportation SoC is 30% in accordance with UN 38.3 Prescriptions
Temperature
Many chemical reactions are affected by temperature, and this is true of the reaction that occurs in a storage battery.
The chemical reaction of a Li-Ion is slowed down by a lowering of the electrolyte temperature that results in less capacity.
A battery that will deliver 100% of rated capacity at 77°F (25°C) will only deliver approximately 75% of rated capacity at
+50°F (+10°C).
At temperatures down to +19.4°F (+7°C) the charge current may be limited to 0.1C depending on other factors, however
at temperatures below +19.4°F (-7°C) charging is restricted by the BMS.
As part of the Performance Warranty, Charge and Discharge shall be in the range +68°F to +77°F (+20°C to +25°C). Any
usage outside this range is not covered by Performance Warranty.
Depth of Discharge (DoD)
Depth of discharge is a function of design. The deeper the discharge per cycle, the shorter the life of the battery. A cycle is
a discharge and its subsequent recharge regardless of depth of discharge.
Charging
The majority of battery capacity/life issues can be traced to improper charging. Improper charging settings may lead to an
overcharging or undercharging condition.
Warranty
Although the BMS of the battery allows a wide range of use, both in terms of temperature and charging currents, this
should not be construed as an implicit authorization to use the battery at these levels. For the purposes of the Performance
Warranty, it is mandatory that the battery is used within the range of temperature and charge/discharge current, and Depth
of Discharge indicated in the Performance Warranty. Warranties only apply to batteries connected via BMS line to an
approved inverter. Any other use, even if permitted by the BMS ranges, is not covered by the Performance Warranty.
