The power factor of an AC electrical power system is defined as the ratio of the true power absorbed by the load to the apparent power
Apparent Power measured in KVA
True Power measured in KW
Reactive Power measured in KVAR
KVA2 =(KW)2 + (KVAR)2
Power Factor= KW / KVA
In general we can say apparent power is the actual generated power and true power is consumed by different loads. True power is measured in watts (KW) and apparent power in volt-amps (KVA).
Usually system power factor varies with respect to different load condition as follows,
Resestive
Voltage and current are in phase with each other i.e., Unity Power Factor(UPF)
Inductive
current lags the voltage i.e, Lagging Power Factor(Lag).
Capacitive
current leads the voltage. i.e, Leading Power Factor(Lead)
Power Factor plays the major role in the grid stability. as the pf is low it will draw more reactive power from the grid and also it affect the transmission system and also machineries. To compensate this, capacitor banks are used to main the power factor near to unity.
Now lets see how the Solar PV plant installation affects the power factor
Let us consider exsisting industy load with recored Apparent power 538 KVA ,True power 500KW & power factor 0.93 with the Capacitor bank of 200KVAR before Solar PV Installation. The system works normally with out any penalty (As per ESCOMS regulation consumer must maintain the PF above 0.9).
So the system works normally without any PF penalty.
Now to the above load, let us add 300KWp Solar plant which will support on an average 200KW loads daytime. Power generated from the solar PV plant is designed to unity power facor(standard regulation). So it will not support the reactive power component.
Now the True power drawn from the grid will reduce to 300KW during daytime & the Reactive power support will not alter as it as 200KVAR capacitor bank.
KVA2 =(KW)2 + (KVAR)2
Power Factor= KW / KVA
As per calculation Apparent power becomes 360 KVA & PF becomes 0.83
So due to reduce in the True power the reactive power requirement has increased & power factor will come down to 0.83.
So in order to maintain the power factor more than 0.9 we need to increase the capacity of the capacitor bank to avoid penalty & also make the system more efficient.