Grid Tie Inverter : Beginners & Expert’s Guide

Unlike traditional solar power inverters, the grid-tie inverter systems offer advanced functionality, which is advantageous to the green power generation process.

Grid-tie inverters not only convert DC power to AC power, but you can integrate them with the grid or utility. That is, you can produce power from your solar panels, and then “inject” it into the electrical power grid systems.

We shall explain the criteria for that later – let’s first look at:

Benefits of Grid Tied Inverter

These types of power inverter systems offer many benefits to the solar power generation process:

• Converts DC to AC, which makes the power ready for use
• By integrating your solar power generation plant to the grid, you can sell excess power thereby making it a source of revenue. You will have a contract on how you will be paid for power supplied to the grid.
• Adapting to the instability of renewable energy sources improves grid stability by adjusting frequency and voltage.

Ideally, these are some of the main benefits of investing in these types of solar power inverter systems. Depending on the solar grid tie inverter design, you may get additional benefits such as power monitoring, safety, and optimization, among other aspects.

How Grid Tie Solar Inverter Supplies Power to Grid

The main distinguishing feature of a grid-tied inverter is the ability to supply the main utility line with power. Remember, every utility power organization sets certain conditions for efficient supply.

Therefore, any independent power producer must ensure the power they supply to the grid conforms to set requirements. This is where a grid-tied invert plays an integral role.

Let’s look at some critical steps:

Step 1: DC to AC Conversion

Like the normal power inverters, these systems have special circuitry that converts DC from solar panels to AC. Remember, power in your utility grid is always in AC.

Step 2: Conditioning AC Power to Conform to Grid Supply Requirements

Before any independent power producer supplies power to the utility grid, the characteristics must match the electrical power grid requirements. Some of these requirements include:

• The voltage can be 120V RMS or 240 RMS
• Frequency which is either 50Hz or 60Hz
• Phase and waveform

As a good practice, your grid tie inverter voltage output should be slightly higher compared to that of the utility grid supply.

A grid-tied power inverter will condition the power from your solar systems to meet the above specifications. Remember, your utility power provider will specify these requirements.

Therefore, your grid tie inverter manufacturer should know your local power supply requirements. Take for instance, in Europe, power transmission companies use 50Hz. Unlike the United States where the transmission is 60Hz.

How to Choose the Best Grid Tie Inverter

Certain attributes will help you choose the best grid-tied power inverter systems. Apart from the obvious variables such as brand or model, you should consider other aspects such as:

Power Factor

Most high-quality grid tie power inverters have a unity power factor (power factor = 1). Remember, low power factor makes power generation expensive. With a unity power factor, the phase angle is one degree.

Advanced Working Technology

The best grid-tie inverter should incorporate technology that ensures safety, efficiency, low operation costs, and seamless integration with the power utility line.

Let’s look at some technologies in grid-tie solar inverters:

• Automatically detect the utility grid waveform
• Automatic disconnection from the grid supply whenever there is a fault in the main lines for safety

A smart application allows you to monitor the working variable of a power inverter. Such systems offer wireless and internet connectivity/integration.

Rated Power

In most cases, you will find this rating in watts. Alternatively, you may find rated power in volts-alternating-current (VAC).

Even as you evaluate the rated power, you should know:

• Output voltage – these may range from 208 to 600 VAC depending on equipment size
• Peak efficiency – Efficiency may start from 94%. Remember, when inverting DC to AC, there are some losses in the form of heat.

In short, you must evaluate all critical aspects regarding voltages and currents.

Operating Modes

Modern systems have many operating modes depending on their designs. For instance, you may have smart load modes, grid-tied modes, or time-to-use modes.

Also, check if the inverter meets the necessary quality compliance and certifications. These may include NEC, IEC 6201, CE, IP, UL, and NEMA, among others.

Where to Use Grid Tie Inverter

Grid-connected inverters are used in renewable energy systems, taking solar power generation systems as an example, to convert the DC power generated by solar panels into AC power that can be fed into the grid, synchronizing the power generation with the voltage and frequency of the grid.

Let’s look at common usage scenarios:

Residential solar power system

Grid tie inverters are commonly used in residential solar panel installations to feed household loads, and any excess power can be fed back into the grid, allowing the homeowner to generate additional income.

Industrial and Commercial Solar Power Systems

Grid-tied inverters are also used in larger commercial and industrial solar power systems, often installed on business rooftops or open spaces. The electricity generated can meet production needs, reducing energy bills and carbon emissions.

Utility-scale solar power plant

Large utility-scale solar power plants use grid-tied inverters to convert the DC power produced by thousands of solar panels into AC power, which is then transmitted to the grid. These power plants can provide large amounts of clean energy to the grid.

Conclusion

If you are planning to supply power to the national grid network, then invest in a high-quality grid tie inverter. More importantly, you should ensure your grid tie power inverter meets your local power utility supply requirements.