Serial vs. Parallel Connections

Serial Connections Serial connections are positive-to-negative in a chain

Serial Connections – PV’s Voltages add –Higher voltage and lower current reduce losses in wiring –Can exceed voltage capacity of charge controller Reduces number of cables to combiner Current is the same through each device

Serial Connections – PV’s 48 volts 5 amps An MPPT controller can take the 5 amps * 48 volts = 240 watts and charge a 24 volt battery with 10 amps (neglecting losses)

Parallel Connections Parallel connections are positive-to-positive and negative-to-negative 12 v PV 5 A v PV 5 A A breaker 10 A breaker

Parallel Connections – PV’s Voltage is the same across each panel Increases number of cables to combiner if multiple panel arrays are used An MPPT controller uses the actual array voltage A PWM controller sets PVs at battery voltage Current adds

Parallel Connections 12 v PV 5 A v PV 5 A A breaker 10 A breaker 12 volts 10 amps

Serial/Parallel Connections – Batteries Batteries must be identical v 220 amp-hour v 220 amp-hour v 220 amp-hour v 220 amp-hour Serial or Parallel ? Serial or Parallel ? Volts? Amp-hours?

Serial/Parallel Connections – Batteries Batteries must be identical v 220 amp-hour v 220 amp-hour v 220 amp-hour v 220 amp-hour Parallel Serial 12 Volts 24 Volts 440 Amp-hours 220 Amp-hours

Serial Connections – Loads Current is the same through all loads –This is the current the source must provide Voltage drops between loads add Voltage available for the next load in series is reduced by the previous load Failure of any load results in failure of all

Serial Connections – Loads Current is the same through each load. If the total of all voltage requirements of all loads is greater than the voltage supplied some will have low voltage and may be damaged.

Parallel Connections – Loads Total current usage adds Same voltage is available at each load Failure of one load may not affect the others Loads with mixed current requirements are not affected (as long as the total current needed does not exceed system capacity).

Parallel Connections – Loads This configuration depicts multiple loads wired in parallel. Each load is rated for the battery voltage. The total current from the battery is the sum of the current through each load, even though each load pulls a different current

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