How Battery Backup System Works

  1. The Photovoltaic Array – Solar photovoltaic modules are mounted on a roof or ground mount where they are nicely exposed to the sun. A proper site assessment with shading analysis can help determine the ideal location for the array.
  2. Array Combiner – Here the wiring for the strings of modules are combined into one common wire before going to the DC disconnect. Fuses or breakers for the individual strings are found here.
  3. Array DC Disconnect – The main disconnect for the photovoltaic array. Basically just a big switch.
  4. Charge Controller – The charge controller accepts the voltage and current from the solar array and modifies it so as to appropriately charge the batteries. This prevents the batteries from becoming overcharged and becoming damaged.
  5. Battery bank – Flooded lead acid, Gel lead acid, or AGM batteries are typically used as a large storage bank of electricity. Generally 24 or 48VDC for bigger systems, 12VDC for smaller systems.
  6. Battery DC Disconnect –The main disconnect for the battery bank. Basically just a big switch.
  7. Inverter / Charger – The inverter /charger converts excess DC power stored in the batteries to AC electricity and feeds it into the house. When the power in the grid goes out, the inverter will disconnect from the grid and only feed the backed up loads of the home. This unit also has the ability to convert AC power from the grid to DC to charge the batteries following a power outage.
  8. AC Disconnect – The main disconnect between the inverter and the grid. Again, basically just a big switch.
  9. Home Mains Panel – Where the power from the grid is split up between all of the different loads for the home. The inverter feeds electricity into the mains panel through a couple of breakers. This electricity goes wherever it is needed, be it in your home or your neighbours.
  10. The Grid – This meter keeps track of what goes into the home and what leaves the home. In this way the home owner is billed for what they take from the grid and credited what they put in with the solar!

NOTE: This is based on a typical system but is not indicative of every system installed of this type. This should in no way be used as a design aid and is for basic understanding purposes only.