The grid tie inverter is the most popular type of inverter today, with global market for this type of inverter being projected to hit $3.9 billion by 2031. That’s according to this report by Allied Market Research. Here, you will learn how a grid tile inverter works and how to use it with a battery backup system should such a need arise. Well also see how to size one for your system.
What is a Grid Tie Inverter?
The grid tie inverter is best defined as a type of inverter that connects to — and communicates with — the grid and does not require a storage system. When used in a solar system, the grid tie inverter means a device that uses the grid as its energy reservoir, allowing you to earn credits that can help offset your energy bills.
Grid Tie Inverter Design
The grid-connected inverter design is a complex one, given that it not only converts DC power to AC power, but also that it ensures the converted power perfectly synchronizes with that of the grid. Typically, it consists of transformers, electronic switches, control circuits, and so on. A grid connected inverter is also one of the following types.
- Grid tie string inverter
- String inverter and power optimizer
- Grid tie micro-inverter
Grid Tie Inverter Specifications
Grid tie specifications, and that are important when buying one, include the following: the input voltage, power rating, its efficiency level, and output AC waveform. These must align with the renewable energy system that the inverter will be used in.
The power rating, for example, must not be lower than that of the energy source which, in most cases, and is the solar panel array. On the other hand, the higher the grid-tie inverter efficiency level, more the amount of DC power that it can change to AC.
Do Grid Tie Inverters Really Work?
Yes, grid tie inverters are highly useful and effective when it comes to integrating your renewable energy system, typically solar, with the grid. They reduce your reliance on the grid, using it only when the sun goes down, which is also when grid energy costs the lowest in most parts of the world.
Besides reducing your reliance on grid power, an on-grid tie inverter allows you to generate power and sell it to the utility company, thereby earning you credits that you can use during the winter season to offset your utility bills.
How Do Grid Tie Inverters Work?
Grid connected inverters primarily change DC to AC for your loads and for export to the grid. A lot more happens, though, when these inverters are in operation. This is the grid tie inverter working principle when used with a solar system:
- During the day when the sun is shining, the inverter takes power from the generating source such as solar array, panels, converts it to AC, and uses it to power your loads.
- However, your consumption during the day is low, while the generation is at its highest. That means there’s excess power that’s not being used.
- The grid tie inverter system is designed to take this surplus power to the grid.
- In some regions, the utility company will pay you for the energy that you export to the grid network, usually in the form of bill credits.
- Later, when your solar system’s generation is low (in winter), you get to offset your higher energy bills using these credits.
- At night when the sun goes down, your panels are not producing any power. During such times, your grid tie inverter automatically connects your loads to the grid.
This grid tie inverter operation method is based on these important parameters; system voltage, synchronization with the grid, and inverter efficiency.
The grid tie inverter voltage is dependent on the voltage of your energy system. In a solar installation, this is the voltage of the panels. This voltage must fall within a specified range; too high, and your inverter may even risk getting damaged. Too low, and the inverter will not work at its most efficient level.
To ensure a seamless transfer of power to the grid, the inverter must ensure synchronization with the grid, usually by matching the grid’s phase, voltage, and frequency levels. The inverter synchronization is made possible by complex algorithms that monitor the utility network, adjusting the mentioned parameters to achieve (and maintain) synchronization.
The inverter efficiency level measures how well the device can convert DC power to AC. Modern inverters that connect to the grid can achieve well over 90% efficiency levels, ensuring optimal power conversion. This is a crucial aspect when it comes to the performance of your energy system.
Grid Tie Inverter with Battery Backup
The typical grid connected inverter system does not use or rely on battery storage. Instead, it directly feeds power to grid to earn you credits. In other words, the inverter uses the grid as a virtual storage system and comprises the following major components:
- Renewable energy system (which is mostly solar panels)
- The solar grid tie inverter itself
- Net meter
- Supporting electrical components such as the junction box and circuit breakers
But a grid tie inverter without battery backup is not useful in an outage. If these are frequent, it can cause a lot of inconvenience. Luckily, though, you can use a grid tie inverter with battery backup. Here is how.
- To use a grid tie inverter with battery backup, all you need is a charge controller. This then forms the link between the inverter and the storage system, ensuring its optimal replenishment and prolonged life of the batteries.
- Another option is to use what’s called a hybrid Inverter. This type of inverter connects to both the grid and solar storage or bank or batteries.
- Instead of sending excess daytime power to the grid, a inverter with battery charger replenishes a storage system, allowing you to own a more reliable power system that works even during an outage.
What Size Grid Tie Inverter Do I Need?
When buying a inverter for solar systems or other energy source, sizing is a critical factor. It ensures you have an inverter that’s compatible with your solar energy installation, which helps ensure its optimal performance. Here’s is how to go about it.
- Choose a grid tie inverter whose power rating is a little higher than that of your solar array or panels. That way, you can be sure the device will be able to withstand or handle the power coming from the array at maximum output.
- Ensure your inverter efficiency is high enough. Electrical efficiency shows how much of the panel DC power the inverter can convert to AC. Therefore, the higher, the better.
- Ensure the inverter is compatible with your specific solar panels. While most inverters today are, it still helps to confirm so before investing in one.
With more people looking for ways of reducing their energy bills, the grid tie inverter is becoming increasingly popular. This type of inverter allows you to feed excess power to the utility system for credits, plus you can use it with battery storage whenever necessary. These inverters are also available in many different sizes and other features to fit different power systems.