Understanding Grid Tie Solar Inverters, Working and Use

Solar Inverter
May 26, 2022
12:58 am

Grid-tie solar inverters have become increasingly popular in recent years. But what does a grid-tied system mean for your solar investment? Read on to learn what grid-connected inverters are and how they differ from other inverters. We’ll also see the benefits of installing a solar system that can “communicate” with the grid.

What is a Grid Tie Solar System?

Also called “grid-connected” or “on-grid,” a grid tie solar inverter system is an installation that generates AC electricity using solar panels and sends it to the grid. In other words, it’s a solar system that uses the grid as its energy reservoir (in the form of bill credits).

A grid tie system usually does not use battery storage and relies on the grid when the panels are not generating enough electricity (at night, for example). During such times, the inverter will automatically disconnect from the grid. A typical grid-connected solar system is made up of these main components:

Solar panels
Solar grid tie inverter(s)
Net meter
Wiring
Supporting components such as AC breaker and junction box

The panels collect sunlight and convert it into DC electricity. The grid-connected inverter transforms the DC electricity into alternating current (AC) electricity before sending it to the grid via the wiring.

The utility company provides the net meter and tracks your system’s electricity. Based on the readings, your utility company credits you for the power you’ve generated.

The Grid Tie Solar Inverter

Grid-tie solar inverters are the types of inverter used in a grid-connected solar system. These inverters tend to be cheaper and easier to install since they do not come with extras, plus they earn you credits that can drastically reduce your utility bills. A grid-connected inverter can be one of these types:

Grid tie string inverter
String inverter with power optimizer
Grid tie micro inverter.

The string inverter has multiple solar panels called strings connected to it. When combined with power optimizers, the system becomes more efficient and expensive. Grid-tied micro inverters connect to the array at the panel level and are the most costly of the three types.

Grid tie inverter connection diagram
Resource: https://www.researchgate.net

How Does Grid Tie Inverters Work?

The grid tie solar inverter’s working principle is just like a conventional solar inverter but with a significant difference: a grid tie inverter converts the DC output of your solar panels directly into AC. Then it synchronizes this AC current with the utility grid frequency.

This is in contrast to a conventional off-grid inverter, which converts DC into AC and then regulates the voltage to match your system’ssystem’s requirements, even if these are different from the utility grid. Here is what happens when you have a solar panel to grid tie inverter.

During peak sunlight hours, the electricity produced by your solar panels may exceed household demand. In this case, the extra power will go to the grid, and you’ll receive a credit from your utility company.
At night or during cloudy weather, when your solar panels are not producing enough power to meet your household demand, you’ll pull electricity from the grid as you normally would.
An on-grid solar inverter must be able to shut down automatically when the utility grid goes down, as feeding electricity into a downed grid can be dangerous.

Grid Tie Inverter without Battery

Grid-tie solar inverters are basically built to operate without batteries, feeding power directly to the grid. During a power outage, since there is no battery backup, these inverters will automatically shut down to prevent any electricity from flowing back into the grid, which could be dangerous for utility workers.

But a grid tie inverter without battery storage is not useful during a power outage. So manufacturers are now making inverters that have both battery backup and the ability to feed electricity to the grid. Read more about them below.

Grid Tie Inverters with Battery

Some grid-tie solar inverters come with battery backup, which means that they can store the electricity generated by the solar panels. This is especially useful during power outages when the grid is down, but the solar panels are still generating electricity.

Grid-tie inverters with battery storage are called hybrid inverters. The batteries help to even out the fluctuations in the output of the solar panels and provide a steadier stream of electricity for your home or business.

Solar Grid Tie Inverter with MPPT Control

Today, grid-tie inverters are designed that use a technology called maximum power point tracking (MPPT). The technology helps to extract the maximum amount of power from solar panels and convert it into AC electricity.

A solar grid tie-inverter with MPPT control will have an algorithm that constantly monitors the output of the solar panels and adjusts the current and voltage as needed. This results in higher output from the solar panels and also helps to increase the system’s electrical efficiency.

Grid Tie Inverter for Solar Home System

Many people installing a grid tie solar system are homeowners looking to reduce their electricity bills. Therefore, they often choose a grid tie inverter explicitly designed to fit their requirements. Here’s how to go about selecting the best grid-tie solar inverter for your home.

Choose Inverter Type

First, choose a type of inverter that will suit your preferences. There are two main types of grid-tie solar inverters: string and micro-inverters. Whichever option you choose will depend on several things, such as the size of your installation, climate, and your budget projections.

Grid tie String Inverter

A grid tie string inverter, also called a “centralized” inverter, is the most common type. It is usually installed next to the utility meter or main breaker panel and converts the DC electricity from all of the solar panels into AC electricity.

The main advantage of string inverters is that they are cheaper than micro inverters. In addition, these inverters are easier to install because they require fewer components and less wiring.
String inverters need all panels exposed to sunlight for peak output. That said, combining the string inverter with DC optimizers and incorporating MPPT technology greatly help to overcome this problem.

Grid Tie Micro Inverter

The grid-tie solar micro inverter, also called a “decentralized” inverter, is installed next to each solar panel and converts the DC electricity from that panel into AC electricity. The AC electricity is then sent to the grid in a frequency and waveform that matches that of the grid.

Micro inverters increase the overall power efficiency of the solar array because each panel can produce electricity independently. This makes them suitable for situations where panel shading is a common issue.
But grid tie micro inverter price is usually higher than that of string inverters. These inverters also require more components and wiring, which can make them more difficult to install as well as maintain.

Other Considerations

In addition to inverter type, there are a few other factors you should consider when choosing a grid tie inverter for your home solar system:

1. Select an on-grid inverter with a power rating greater than that of your solar panels. This will ensure that it can handle the maximum output of your solar array.

2. The grid tie inverter efficiency rating indicates how much DC power can convert into AC electricity. Higher efficiency means more efficiency, resulting in more electricity being sent to the grid to earn you credits.

3. Ensure the inverter is compatible with your solar panels. Most grid-connected inverters are compatible with most solar panels, but it is still important to check to be sure.

4. Finally, select an inverter that is from a reputable brand. Grid tie inverters are available from a variety of manufacturers. Choose an inverter from a brand that you can trust.

Conclusion

Grid-tie solar inverters are becoming increasingly popular as more people look for ways to reduce their electricity bills. These inverters allow you to sell excess electricity to the grid, offsetting your electric bill. Grid-connected inverters are available in a variety of sizes and with a variety of features. When considering investing in this type of inverter, select one with the features you need.

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