What is a Grid-Tied Inverter?

By Matthew Joseph Nandirio •  Updated: 10/07/22 •  6 min read

Although sunshine is a very good source of energy, it is not always available. Therefore, if the sun isn’t shining, you’ll need to import energy or consume energy that was previously saved.

A grid-tied system, the most popular in the USA uses solar panels to generate electricity from sunlight just as a conventional system.

When there is excess energy, it is exported to the utility grid; likewise, when a household needs more energy, it imports it from the grid.

This system doesn’t have any kind of solar power storage system, no batteries.

A Grid Tie Inverter

A specialized inverter receives power from your solar panels and converts the DC voltage they produce directly into grid-compatible AC power. The grid-tie inverter enables your home to not just import power from the utility, but export power to the utility as well.

When solar energy is available for usage, the inverter distributes power to your household appliances directly from the solar panel. In the instance that there is not enough solar energy, it switches back to grid power.

How exactly does a grid-connected solar inverter send “extra” electricity back to the utility?

The grid-connected solar inverter operates according to a simple basic electrical theory. From a higher potential to a lower potential, the current flows.

The grid-connected solar inverter attempts to keep its output voltage greater than the grid voltage. Net current flow from solar to the grid is the result of this. It’s still not as easy as it seems to do this. For effective transfer, the alternating current from the inverter must be in phase with the grid.

Functions of a Grid-Tried Inverter

As you already know the inverter is there to convert the solar power to usable AC power but is not the only thing. There are a few other functions you might want to know.

  1. Energy conversion – depending on the household requirement the inverter will convert the DC energy to AC energy.
  2. Track the power production – The grid-tied solar inverter makes it simpler to monitor power generation. As a result, excess power generation can be observed with time.
  3. Grid Assistance – A two-way connection to the electrical grid is made possible by the grid-tied solar inverter. The inverter will pull energy as needed and feed any excess energy back into the grid. Additionally, it recognizes any grid interruptions and enables the solar system to enter a safe mode.
  4. Power Optimization – The on-grid inverter optimizes and controls the power output to handle fluctuations.

Is Grid-Tied Inverter Best for Solar Panels?

Grid-tied PV inverters perform an additional task in addition to converting solar energy from AC to DC making them best for solar panels.

It analyzes energy flows in real time to decide whether solar energy should be used domestically or exported.

It synchronizes the output voltage and frequency well with the connected grid. The output of the inverter also increases as solar energy does, feeding more energy into the grid.

Types of grid-tied solar inverters

If you want to know the types of grid-tied solar inverters, there are 3 types of inverters,

  1. String Inverters,
  2. String Inverters Paired with Power Optimizers, 
  3. Microinverters.

The string here refers to a series of solar panels. The string inverter is connected to a series of solar panels. String inverters gather all of the DC energy produced by your solar panels and convert it to AC energy at a single spot.

Each panel in String Inverters Paired with Power Optimizers has a separate optimizer component; thus, the power output of each panel is individually optimized. Power conversion from DC to AC is centralized in this setup.

Microinverters are commonly mounted on the back of each solar panel in systems. They eliminate the need for a separate string inverter by converting the DC electricity from your solar panels into AC electricity on your roof.

Pros of grid-tied inverters

You will always experience some advantages when using a grid-tied solar inverter compared to other solar panel systems.

  • Low cost

Rather than a hybrid system with a battery, this is way cheaper. This system needs only a few pieces of equipment so the initial cost is always low. 

  • Net metering 

This will meter the surplus power which you can sell to the grid. This will significantly reduce your electricity bill.

  • More reliability

As there will be less equipment, there won’t be more failures. And most of the time, you can survive with the national grid.

  • Easy maintenance and installation 

The on-grid solar power system is the easiest to install as it has few pieces. The lack of batteries and fewer pieces of equipment make maintenance quite simple.

Cons of grid-tied inverters

  • No power during a grid outage

Just imagine it is nighttime and there is also no supply from the grid. Grid-tied solar systems don’t have battery storage; thus, they don’t offer backup power too.

To avoid transmitting power across utility power lines, where workers might be at work, grid-tied solar systems are built to shut off when the grid goes down.

Which solar inverter size do I need?

There are plenty of solar inverters of different sizes in the market, big and small. Just as with solar panels, an inverter’s size can be measured in watts (W). You should generally match the wattage of your solar panels when selecting a grid-tied solar inverter. If your solar panel system has 5000 watts of capacity, therefore You will require at least a 5000 watts inverter

other than that, two more factors geography, and site-specific conditions will affect the inverter sizing.

Grid-tied inverter price

The price of a grid-tied inverter will vary with its capacity, technology and the manufacturer. Grid-tied inverters are considered a cost-effective option due to their long lifetime. A good inverter will require very less maintenance and service making them more economical. You can find inverters from $70 to $1650 on the market.

Final thoughts

Grid-tied solar inverters are economical and a safe option for your solar power generation system with a potential income too. Before installing the inverter remember to check your local policies, rules and regulations regarding grid-tied systems. For quality, output check standards also.

References

https://www.usaid.gov/energy/powering-health/technical-standards/inverters

https://www.youtube.com/watch?v=_VlxzDXtKuM

https://www.youtube.com/watch?v=sZBtN9OAHtw

https://youtu.be/62UmQoKUBR4

S. Narendiran, “Grid tie inverter and MPPT – A review,” 2013 International Conference on Circuits, Power and Computing Technologies (ICCPCT), 2013, pp. 564-567, doi: 10.1109/ICCPCT.2013.6529017.

Kumar, A., Gupta, N., & Gupta, V. (2017). A Comprehensive Review on Grid-Tied Solar Photovoltaic System. Journal of Green Engineering, 7(1), 213–254. https://doi.org/10.13052/JGE1904-4720.71210

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Matthew Joseph Nandirio

Matthew Joseph Nandirio is the Founder of walkingsolar. After graduating from the University of Houston in 2002, matt started working as an electrical and electronic 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”.

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