This is a new addition to the grid-tie inverter. First, let me explain the system very well! If you have a hybrid inverter with off-grid capability, you can successfully switch the system. But, the question is how?
Here’s come a small twist. Before you move on, you need to disconnect the grid side when the power goes off. Then, simply put the system in off-grid mode and operate it. However, you will still need batteries; otherwise, the inverter would shut down. If you find the PV output cannot satisfy the power load, you have to install batteries.
Now, to understand the entire mechanism clearly, you have to learn an entirely new chapter. What is it? It is a system of Grid-tied, off-grid, and Hybrid solar inverters.
Grid-tied inverter systems
A grid-tied or on-grid solar system is directly connected to the utility power grid. Hence it’s called ‘grid-tied!
Fortunately, this system offers a higher efficiency rate. Moreover, its lower equipment and installation charge enables optimum benefits for the users.
If you are looking for a cost-saving option grid-tied system is an ideal choice. Henceforth, many homeowners install this inverter system for better utility. On the other hand, net metering plays a crucial role here. Apart from that, a residential solar system is a feasible option.
Equipment needed for the GTI system
Using two basic pieces of equipment, you can install the system.
- Grid-tie inverter
- Power meter
As the name suggests, it is a standalone infrastructure. Moreover, once you have access to the grid, the question of off-grid never comes to mind.
In addition, to ensure the supply of electricity, this system requires a backup. Of course, battery storage takes control if anything goes off. However, this battery bank needs to be replaced at least after ten years of interval.
Interestingly, off-grid refers to self-sufficiency. Most importantly, it is cheaper. On the downside, the supply of a battery bank might pose an issue here. Unfortunately, consistent cloudy weather can be another challenge for the owners. In that case, they need to install an additional generator to continue the power supply.
Equipment needed for the off-grid system
- Solar charge controller
- Additional DC connector
- Off-grid inverter
- Optional back-up generator
- Battery bank
In this case, a potential charge controller is fundamental. On the other hand, based on the regional setup, owners also need additional backups.
It combines both grid-tied and off-grid mechanisms. However, this system is quite complicated compared to the other two. Fortunately, it is much cheaper than the installation of an off-grid system.
As a smart inverter technology, it offers various promises. Hence, it still has room for innovation. Consequently, the owners can temporarily store the excess electricity in the batteries. Then they can also put it on through the utility grid.
Equipment needed for the hybrid system
- Charge controller
- Sustainable battery bank
- Additional DC connector
- Battery-based grid-tie
- Robust power meter
Understanding grid-tie inverter
So, a grid-tie inverter converts DC or Direct Current into AC or Alternating Current. Hence, it prepares the system to inject the electrical power grid. Usually, the voltage ranges within 120 V.
However, the inverter should match the voltage to infiltrate the electrical power securely into the grid. Moreover, with net metering, the excess power would be recorded.
Now, let me discuss the operational mechanism of the grid-tie inverter:
- An efficient grid-tie inverter can generate lined-up voltage. Hence, it matches the higher parameter of the AC power grid.
- It also has an onboard computation system. Interestingly, this automated system can analyze the AC grid waveform and the output voltage.
- In addition, it also can disconnect the grid when the utility goes down. In fact, it is an NEC requirement to ensure any blackout. Hence the inverter gets shut down to prevent energy transition.
- Moreover, the configuration enables the owners to use the alternative power system. However, if the energy source is not sufficient, it automatically consumes the power from the electricity grid.
- Its conventional and low-frequency type is suitable for AC and DC suitable grids. In addition, the transformer uses an automated computing process to convert high frequency into Direct Current. Then, it is converted to Alternative Current output.
Grid-tie inverter that does not feed into the grid
This process is often practiced. However, it is still not widespread. If you follow the following process to enable the GTI, that doesn’t feed into the grid.
Finally, the inverter power generation capacity must the large enough to produce the capacity of a Grid-tied inverter. Then, the grid-tie inverters are connected through a switch and allow a safe disconnection. To monitor or protect the circuit, a relay can be used.
However, you need to make there are adequate loads to absorb the power. Typically, it should be large enough to absorb the power from the GTI. Once it is fully charged (90%), you can disconnect the protection relay.
Can I use a grid-tie inverter without Netmeter?
If you have ZED Advance available, you might not need net metering. Moreover, you don’t need any approval from the state electricity grid with a Grid-tie inverter.
Hence, commissioning a net Metering is possible with ZED Advance.
How to trick a grid tie inverter?
You can trick a grid-tie inverter with an off-grid system. The off-grid system is a tricky method that needs a 600-volt string inverter. If you can add battery backup to an existing grid-tied, it can automatically turn on the power of the critical appliances.
Can a hybrid inverter work without a grid?
An off-grid inverter can work with an off-grid solar system as it needs enough space to store energy for at least two days. Similarly, hybrid system inverters use hybrid grid connectors. The battery needs to be large enough to supply 5 to 10 hours of energy based on the application.
Can we connect the grid-tie inverter directly to the off-grid system and use it without connecting it to the grid?
YES, YOU CAN. However, you have to modify the control system of the inverter. Hence, it will help the control system to switch between grid operations and standalone operations.
Eng. Matthew Joseph Nandirio is the Founder of walkingsolar.
After graduating from the University of Houston in 2002, matt started working as a Solar Electrical Engineer for several multi-national solar energy companies.
He has a wide range of experiences including solar system requirement analysis, planning, maintaining, debugging and even solar device development through research.
He now shares his 20 years of expertise through his articles on the walkingsolar website.
Further, he is also the author of two books on Solar Technology, “Solar Power for Villages” and “DIY Solar System for Dummies”.