How does a solar grid-tied system work?

For homeowners considering installing solar panels, an important consideration is whether or not the home’s solar panel system should be connected to the grid (grid-tied) or off the grid.
Although off-grid homes were more common in the past, grid-tied homes are increasing as the affordability and popularity of solar systems increase.

What is a grid-tied system?

A grid-tied solar panel system is simply a solar energy system that is connected to the electrical grid and, therefore, uses electricity from both the solar panel system and the electrical grid. Because of this, a grid-tied solar system doesn’t have to meet all of the electricity demands of the home.
If needed, the home can draw energy from the grid at times (such as on cloudy days or at night) when solar panels are not producing at full efficiency. Likewise, if more energy than is needed is generated by the solar panels of one home, that excess energy will be fed into the grid for use elsewhere.

Connecting your home to the grid

Connecting your home to the grid will require involvement from you and the provider of your solar panel system.
For starters, your solar system provider must know the local interconnection laws. The interconnection laws are rules and procedures that specifically apply to situations where a renewable energy system such as a solar energy system is “plugged” into the power grid. The interconnection laws state the terms that must be followed by both solar energy system owners and utilities.
In order to get started with a grid-tied system, your solar system provider will file interconnection and net metering applications to the utility company.

Benefits of a grid-tied system

A grid-tied solar system has several major advantages over off-the-grid solar systems:
Reliability: Solar panel systems are not perfect. There are bound to be days when efficiency is not what it could be and the system doesn’t produce enough. However, many of your daily (and nightly) activities will continue to require the use of electricity.
Unlike off-grid systems which may run out of power, grid-tied solar systems are less likely to leave you in the dark at inopportune times. If the power generated from your solar panel system is less than optimal, extra energy will be pulled from the grid. The grid essentially acts as a backup for your solar energy system.
Less energy is wasted as a result and the efficiency of your solar power system goes up. Except in the event of a power outage, you will always have access to electricity during any time of day, as long as your system is connected to the grid.

Costs: To function properly, off-grid solar energy systems require more specialized equipment that gets expensive quickly. Clearly, less equipment generally means lower installation and maintenance costs. This happens to be the case with most grid-tied systems. Since the power grid functions as a battery for your system, you not only don’t have to pay for batteries, you do not have to pay for the maintenance that is involved with those batteries.

Net metering: The key concept to understand about a grid-tied system is that it gives you the ability to feed power to the grid during the day, when you may be producing excess energy, and to use the grid supply at night. Net metering is a billing process that credits the owners of grid-tied systems when they produce more energy than the home needs.
Because grid-tied homes are usually net-metered, the power meter tracks this exchange between your solar system and the grid. Excess energy generation leads to your power meter spinning backward rather than forward, thus giving you a credit. The credit can be used to offset payments for future power usage.