What Are Off-Grid and On-Grid Solar Energy?

An off-grid solar energy system is not connected to the utility grid, whereas an on-grid (aka grid-tied) solar energy system is connected to the utility grid. Whether off-grid or on-grid system will determine your access to electricity, what equipment is needed for excess production, what happens when the grid goes down, and how you’re billed for electricity.

Difference 1: Your Access to Electricity

Electricity Access with Off-Grid Solar

If your option for a solar system that is not tied to the electric grid and you do not have a generator, you will only have electricity at two points:

When the sun is shining and your solar system is producing electricity.

When you’re pulling electricity previously generated by your solar system from a solar storage device, like batteries.

If you do not have batteries or a means to store your energy, you will have less or no electricity when it’s cloudy, and you will not have electricity at night.

Electricity Access with On-Grid Solar

If your system is not producing any electricity or not producing enough electricity to power the devices, lights, machines, etc. that you’re using, you can pull energy from the utility grid to supplement it. This ensures you always have enough electricity for what you need.

Difference 2: What Happens When the Grid Goes Down

Power Outages with Off-Grid Systems

Your solar system is working independently from the power grid. If there’s a bad storm or event that knocks out the power, your solar system can continue operating. You won’t notice changes in your service or access to electricity.

Power Outages with Grid-Tied Systems

By connecting to the grid, you get access to electricity whenever you need it. However, you’re also subject to some rules. If you have a grid-tied solar system and the grid goes down, you will not have electricity, unless you opt for a grid-tied solar system with battery backup.

Difference 3: How You’re Billed for Electricity

Electricity Bills with an Off-Grid System

If your PV system is not tied to a grid, you won’t receive an electric bill at all. However, even with no electric bill, off-grid systems are often more expensive because of the additional equipment like batteries that are needed to make it viable.

Electricity Bills with a Grid-Tied System

If your option for a grid-tied system, you could still see a few minimal charges on your electricity bill, even if your solar system provides 100% of your electricity.