Complete Guide to Power Factor [Power Factor Calculation]

• Beer indicates the active power (kW). Liquid beer is useful power or energy that is doing work.
• Foam indicates reactive power (kVAR). It is wasted power or lost power that isn't doing any work, such as vibration or heat production.
• The mug is the apparent power (kVA) or demand power. It indicates the power that's delivered by the utility.

If the circuit is 100% efficient, the demand will be equal to the power available. If the demand exceeds the power available, the utility system is strained. Many utilities charge more from customers when demand is higher than supply. Utilities also apply surcharges to companies with a lower power factor. A low power factor means a less efficient circuit and high overall operating costs.

Importance of Power Factor

Power Factor (PF) is essential to consider when dealing with AC circuits. If the PF is less than 1, the circuit's wiring will carry more current than what would be necessary with zero reactance. The poor PF makes an inefficient power delivery system.

Many industrial and commercial electrical systems generally have a low PF, meaning customers are not fully utilizing the electrical power they are paying for. In such instances, additional energy is required to operate the load, which, in turn, requires the utility to provide more current.

How to Calculate Power Factor

If you want to calculate the power factor, you first need to determine the working power (kW) and apparent power (kVA).

Here’s how to calculate the power factor:

Power Factor = True Power ÷ Apparent Power

Or, PF = kW ÷ kVA = W ÷ VA

Where W means useful power and VA means supplied power.

In other words, the PF is defined as the cosine of the angle between current and voltage. Under ideal conditions, the phase difference between voltage and current is 0 in AC circuits. However, there exists some phase difference between the two in real situations.

In the below figure, the angle ɸ is the phase difference between voltage and current.

VI sin ɸ = Reactive Power (in VAR)

VI cos ɸ = Active Power (in Watts)

VI = Apparent Power (in VA)

PF = cos ɸ = Active Power (W) ÷ Apparent Power (VA)

Good, Poor, and Bad Power Factor

It's advised that the system's power factor not fall below a certain level. If it does, reactive power charges will occur. Anytime the PF falls below 0.95, the power supplier will define a specific charge.

1.0 is generally indicated as the perfect power factor and can be achieved in an ideal system. The power factor of commercial buildings is usually rated between 0.98 and 0.92, with industrial PF falling below 0.7.

Here's a table that reveals the good, poor, and bad power factor:

A power factor can be lagging, leading, or unity. Let's explain them briefly:

Lagging Power Factor: If the current lags behind the circuit's voltage, the circuit's power factor is called the lagging power factor. This happens when the circuit is inductive. Some examples of inductive loads that have a lagging power factor include coils, motors, and lamps.

Leading Power Factor: If the current in the circuit leads the voltage, it is called the leading power factor. Ideally, a capacitive circuit has a leading power factor. Some examples of capacitive loads include capacitor banks and synchronous condensers.

Unity Power Factor: Ideal circuits typically have a power factor of unity. This is called the unity power factor when the circuit's voltage and current are in phase.

Effects of Low Power Factor

A low power factor, which measures how efficiently a system uses electricity, can cause energy losses. This is because a low power factor means that a significant amount of the generated power is not being used efficiently. Here are the three common effects of low power factor:

Large Copper Losses: The copper losses are directly proportional to the square of the line current, which is then inversely proportional to the circuit's power factor. In other words, the copper losses will be inversely proportional to the square of the power factor. If the PF is low, the line current will be high, and copper losses will be higher. As a result, the power system will have low efficiency. 

Large kVA Rating: Electric machines, like transformers, are rated in kVA. Here's how the power factor and kVA are related: kVA = kW ÷ Cos ɸ. The PF is inversely proportional to its kVA rating.

Poor Voltage Regulation: Poor PF means the electrical equipment will draw a larger line current. A large current at a low lagging PF causes a higher voltage drop in alternators and transformers. This often leads to decreased voltage available at the equipment's supply end and poor voltage regulation.

Now that you know the effects of PF, here are some causes of low PF:

Harmonic Current: A harmonic current often reduces the system's power factor.

Improper Wiring: Electrical accidents or improper wiring causes an imbalance in the 3-phase power and low power factor.

Inductive Load: 90% of industrial loads often consist of induction motors, which draw magnetizing current to set up a magnetic field for proper operation. Hence, they work at a low power factor.

If you're wondering how to correct the power factor, all you need to do is add capacitors and inductors to the circuit system. It will help you realign the current and voltage into the required phase to convert the PF of one or closer. You can use capacitor banks or synchronous condensers to correct low-power factors.

Effects of Solar on Power Factor  

Under normal conditions, solar inverters will output only real power and will not influence the reactive power drawn from the grid. When the real power provided by the grid is reduced, and reactive power remains constant, the ratio of real to apparent power is also reduced.

There are two ways to correct power factor issues:

Use A Power Factor Correction (PFC) Unit

The PFC units compensate for the reactive power being drawn to offer a better or near-perfect power factor. Traditionally, these units were capacitor banks, but they are now similar to solar inverters. This will ensure that customers fall back within network regulations and achieve better financial outcomes.

Use the Right Auxiliary Equipment

Some solar inverters can dedicate some of their capacity to PFC units. The right auxiliary equipment ensures the solar inverters can be configured to offer limited amounts of PF correction. This means the solar inverters will either have excess capacity or limit their output to free up capacity.

The integration of solar production can negatively impact the overall power factor of the electrical installation. That's why it is essential to understand how to avoid power factor degradation due to the integration of solar production. To do this, all you need to do is regulate the inverter's point. This will ensure the solar inverters can provide both active and reactive power. As a result, you can improve the global PF of the electrical installation to the expected value.

Jackery Solar Generators Explained

Jackery is a renowned manufacturer of high-quality solar generators, portable power stations, and solar panels. The Jackery Solar Generators combine Jackery Portable Power Stations and Jackery SolarSaga Solar Panels to collect, convert, and supply electricity to the household or outdoor appliances.

The built-in and reliable pure sine wave inverter in portable power stations ensures the safe conversion of DC to AC electricity for appliance charging. The MPPT charge controller also provides a secure and reliable solar charging experience. Here are three popular Jackery Solar Generator models that are designed to meet power needs during different use cases:

Jackery Solar Generator 3000 Pro

The Jackery Solar Generator 3000 Pro is the ultimate power master that can charge 99% of household or outdoor appliances for long hours. The portable suitcase design with a foldable handle and double wheels ensures you can easily carry the power station anywhere you like. The solar generator can also be integrated into the home circuits via the Jackery Manual Transfer Switch. You can select up to 6 circuits from the breaker panel, such as lights, refrigerators, garage doors, etc., so they start charging in the blink of an eye during extended blackouts.

Appliances Running Time

• Refrigerator (400W) = 6.4H
• TV (100W) = 25.7H
• Coffee Maker (500W) = 5.1H
• Microwave (1000W) = 2.5H
• Air Conditioner (1100W) = 2.3H

Customer Review

"The 3000 Pro is a beast. Both are well-made and work great. I now have 6 panels that I can use at the same time to quickly charge the 3000 Pro. Good warranties. Buy with confidence." — Dustin M.

Jackery Solar Generator 2000 Plus

The Jackery Solar Generator 2000 Plus is a portable and powerful charging solution for powering 99% of household or outdoor appliances. It's an ideal emergency home backup solution that ensures essential appliances, such as refrigerators, lights, and medical equipment like CPAP machines, remain functional. It has a foldable handle, a flat top, and a suitcase-style shape for easy transportation to various locations. If you want more power for your household or outdoor appliances, you may consider expanding the battery from 2kWh to 24kWh.

Appliances Running Time

• Refrigerator (400W) = 4.3H
• TV (100W) = 17.3H
• Coffee Maker (500W) = 3.4H
• Microwave (1000W) = 1.7H
• Air Conditioner (1100W) = 1.5H

Customer Review

"I read a lot of reviews, and we decided that the 2000Plus series was the best package for our situation. Operated various appliances, including a mid-sized electric heater. Performed as expected. Purchased for emergency situations, and I believe it will do the job." — Julie Botsko.

Jackery Solar Generator 1000 v2

The Jackery Solar Generator 1000 v2 can run low to high-power-consuming appliances in households or during outdoor adventures. It features multiple output ports to charge refrigerators, portable kettles, portable air conditioners, televisions, lights, and other essential household or outdoor appliances. It also features a foldable handle and ergonomic design to carry the portable power station to outdoor adventures and easily run many campsite appliances.

Appliances Running Time

• Refrigerator (400W) = 2.2H
• TV (100W) = 9.0H
• Coffee Maker (500W) = 1.8H
• Microwave (1000W) = 54 minutes
• Air Conditioner (1100W) = 49 minutes

Customer Review

"The best secondary power supply I've ever been in possession of. Thank you, Jackery!" — Robert McAuliffe.

FAQs 

What size of solar generator do I need?

The size of solar generator needed for house or outdoor adventures will depend on the total wattage of the appliances charged simultaneously and the time for which you need to power them. For example, if you want to run a refrigerator (400W), TV (100W), and portable fan (50W) during a power outage with the Jackery Solar Generator 3000 Pro, the working hours can be calculated as follows:

Working Hours = Battery Capacity in Wh × 0.85 ÷ Operating Wattage of the Appliance = 3024Wh × 0.85 ÷ 450W = 5.7H.

Note: We have multiplied the battery capacity by the power conversion factor (0.85) to account for the power loss that happens when charging the appliances.

What does an 80% power factor mean?

If the power factor is 80%, it means only 80% of incoming power does the useful work. For example, if the working power is 100 kW and the apparent power is 125 kVA, the PF will be 80%.

What is a good power factor?

The good power factor lies between 1.0 and 0.95. When the true power and apparent power become equal, it is called a good power factor. When the PF of a system is equal to 1.0, the system is called perfect.

What does 100% power factor mean?

The equipment performs best when the PF lies between 90% and 100%. The apparent power or total power the facility draws is the square root of the sum of the squares of reactive and real powers.

What is a typical residential power factor?

A typical residential power factor (PF) is between 0.80 and 0.98 but can range from 0 to 1.0.

Final Thoughts

Power factor can affect the total energy costs and lead to high electricity bills. Improving the power factor will help you improve efficiency and offer significant economic savings. When the power factor is less than 90%, the utility company charges a power factor surcharge. It's used to recover the cost of reactive power supply, which isn't typically included in other charges.

Understanding what the power factor is and its formula, you can easily calculate the PF and take some measures to correct it. If you're looking for an alternative solution to reduce total energy and electricity costs, you may consider investing in Jackery Solar Generators. These portable and powerful solutions can charge most household appliances, reducing reliance on the electricity grid and saving money.