Types of Battery Systems

 

1.Battery ‘Backup’ system:  Components

Battery backup systems are those systems that are connected into the grid network and operate essentially as a grid-connected solar system.  However they have the extra ability to charge a small battery bank and maintain power to an additional and separate AC load circuit.

Therefore, whenever there is a power outage on the grid network or during night time when there is no sunlight, the batteries can maintain power to those separate AC loads.  Note that these systems cannot maintain power to the entire house, only to those “selected” AC loads.

Components:

  • Solar PV array (solar panels on the roof)
  • Special “Multimode-Inverter” that both charges batteries and converts battery DC to AC household electricity
  • Smaller battery capacity to maintain power to selected AC loads
  • Priority is to charge the batteries from the solar during the day
  • If batteries are fully charged, then solar supplies power to the connected household appliances
  • Any excess solar energy is fed into the grid for any Feed-in-Tariffs
  • System maintains power to selected AC loads during power outages

Note with all battery backup systems:  There are essentially two (2) AC circuits in the house.

  • 1) Separate AC “MAIN HOUSE LOADS”
  • 2) Separate AC “BATTERY LOADS” (selected appliances and generally not very big electrical loads)

Battery backup

 

2.  Battery ‘Hybrid’ System: Components

Battery hybrid systems are also connected into the grid network and also operate essentially as a grid-connected solar system.  However they do not have any special additional AC circuits, and therefore no additional modifications or AC wiring is required for the house.   The disadvantage is that if there is a power outage on the grid network, then the system automatically shuts down as a safety function, just like a normal grid-connected solar system.

Battery capacity sizes can be slightly larger than a battery backup system, as they are requiring to supply power to the whole house.

Components:

  • Solar PV array (solar panels on the roof)
  • Special “Multimode-Inverter” that both charges batteries and converts battery DC to AC household electricity
  • Can be a larger battery capacity to maintain power to the whole house
  • Priority is to charge the batteries from the solar during the day
  • If batteries are fully charged, then solar supplies power to the connected household appliances
  • Any excess solar energy is fed into the grid for any Feed-in-Tariffs
  • System will shut down during power outages

 

Battery hybrid

 

3. Battery ‘Stand-Alone’ System

Stand-alone power systems are not connected to the grid network.  They are a fully self-generating system that may have multiple sources of energy resources, such as solar, wind and a generating set (genset).

These systems can be configured to operate in many ways, but the most common is using a common “AC bus”, whereby all the energy resources are connected into.

The battery banks in these systems have much larger storage capacity, due to their requirements to power the loads over several days.

Components:

  • Solar PV array (solar panels on the roof, or ground mounted arrays), with its own inverter to supply AC power into the AC bus.
  • Special “Battery Inverter” that both charges batteries and discharges the battery with the DC to AC conversion to supply household electricity
  • The actual batteries which are generally have a large storage capacity
  • Optional diesel generator can be included for back-up if there is little to no sunlight
  • Optional to add a wind turbine to add overnight generation when sun is not shining

Stand-alone