In off-grid systems, the main focus is on covering consumption. Since there is no grid that can cover the consumption when required, the PV system, battery system and - if available - the auxiliary generator must take over this task.
In contrast to grid-connected systems, load shedding can be set for the consumers of off-grid systems. Load shedding ensures that less important loads can be switched off when too little energy is currently available from PV, battery or auxiliary generator.
The energy of the PV system can also be controlled. This is necessary if the consumers and the batteries together cannot absorb as much energy as the PV system produces.
In off-grid systems, the following energy management determines when the energy is exchanged between the players in the system (PV, load, battery, additional generator if necessary).
Direct consumption Consumption is directly covered by PV energy
Discharging Consumption is covered by the batteries
Consumption coverage of auxiliary generator If the energy from PV and battery is not sufficient, the generator jumps in, if available
Charging from the PV Excess PV energy is used to charge the battery.
Maintenance charge (charging from the generator) Batteries are charged with energy from the auxiliary generator if charging methods are used to maintain the batteries (boost, full and equalisation charging) and PV energy is not available in sufficient quantities.
The consumers in PV*SOL® can be defined in different groups for off-grid systems. Usually, three groups are defined in more complex off-grid systems:
Load shedding is defined individually for each group and depends on the state of charge (SOC) of the batteries. Two time windows can be defined for each group.
The results show the difference between previously stated and actually covered consumption:
If the PV system supplies more energy than can be absorbed by consumers and battery storage, the PV system must be throttled. This is done automatically. The results show the difference between maximum available energy and energy consumed: