Understanding Grid Interactive Systems

From utility-dependent to off-grid and everything in between

At Northern Arizona Wind and Sun, one of the most frequent conversations our sales and engineering team has with customers is the “off-grid” discussion.

A widespread misconception is that you have only two options: connected or disconnected from the grid. One of the most common configurations that are becoming increasingly popular is a mix of both.

A grid-interactive or grid-tie with a battery backup system allows one to reap the benefits of being connected to the utility grid when needed while also providing energy independence and backup when the grid is unavailable.

In the video below, James Hall, our sales manager and application engineer, discusses the range or spectrum of options.

If you are exploring solar options, and we hope you are, we break down the basics of what each type of system offers and why you might choose that system.

We encourage you to reach out to our sales and engineering team to answer any questions you might have. We offer turnkey solutions to our customers, from your first pre-sales question to product support post-installation.

A spectrum of systems, Grid to Off-Grid – What do I need to know?

Utility Connection

Let’s start with the basics. Most homeowners receive their electricity from the grid. What is the grid? “The grid” is a complex network of generation facilities, transmission lines, and transformers that transport electricity from the generation source to your home or business.

This helpful infographic from energy.gov shows how electricty goes from the generation source to your home.

You likely have a grid-powered home if you live in or near a city. You may receive a monthly electric bill and, for the most part, probably don’t think much about it until the grid goes down.

What causes the grid to go down?

There are a variety of reasons the grid can go down.

Weather events are the most common, such as extreme temperatures or severe weather like tornados, fires, hurricanes, and ice storms.

The grid can also go down when there is a high level of usage, usually related to excessive heat. Some cities will use a rolling blackout system to preserve power by limiting use in increments.

Technical issues, human error, and even the threat of cyber manipulation can cause minor or extensive power outages.

Now that you understand where your power comes from and what can cause you to lose it, let's talk about your options for solar.

Grid-tied solar

Let’s assume you decide you want to offset some of your energy consumption, either to reduce long-term costs over the course of owning your home or to rely less on fossil fuels. Whatever your reasoning, to do this, you would need the following equipment:

Solar Panels

  • Each panel comprises a layer of silicon cells, a metal frame, a glass casing surrounded by a particular film, and wiring.  If you want to read more about how solar panels work and creative energy, you can read that here.
  • The number of panels you need can be determined by the amount of electricity you need, commonly referred to as “load.”

Inverter

  • The energy created by the solar panels is sent to an inverter, which converts the energy to AC power that can be used in your home to power your electric appliances and devices.

Advantages:

  • Reduced dependency on the grid.
  • In some municipalities, you can “sell back” your excess energy to the grid. You may be able to receive credit from the utility company providing your electricity.
  • Solar production offsets home usage during the day, reducing the cost of the electric bill.

Drawbacks:

  • A traditional grid-tied solar system is forced to shut down whenever a grid outage occurs to prevent back-feeding power onto the grid. When a power outage occurs, the utility company often sends line workers to diagnose or repair the issue. To avoid harming these line workers, the inverter must disconnect itself from the grid during a power outage, thus rendering the entire grid-tied solar system inoperable until the grid resumes. Even if a power outage happens in the middle of a bright sunny day, a grid-tied solar system is required to shut down.

Grid-Tied with Battery Backup or Grid-Interactive system

With a Grid-tied or Grid-Interactive system, the added component of battery backup is used with the Inverter system to create power storage. The solar panels send the electricity to the inverter. The batteries support the inverter. In times of heavy electricity use, the batteries will supplement the energy coming from the solar panels. At night or when the sun is not shining, the battery system will power your home instead of the grid or the solar panels. The inverter can be programmed to draw power from different sources.

If the grid goes out, your inverter will automatically disconnect from the grid just like a standard grid-tied solar system would. However, with the addition of batteries, a grid-interactive system continues to operate during a grid outage, day or night. In a grid outage, this system can be designed to power the entire home or select a few critical loads until the grid resumes. Because your home is self-sustained with your battery backup, your panels will keep gathering energy from the sun and replenishing the batteries, even while others might be without power.

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Have a question? Give us a call or shoot us an email: 1.800.383.0195 or sales@solar-electric.com.

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