Grid

Grid-tied vs. off-grid solar: decide whether a grid-tied solar system with battery backup or an off-grid solar system is best for your home or farm.

I’m having trouble understanding the differences between grid-tied vs. off-grid solar and battery backup systems. Can you please break it down for me? — Lee, New Braunfels, Texas

I hear from a lot of people who are concerned about the reliability of electric service when severe weather strikes their area. Explaining grid-tied vs. off-grid solar and battery backup is a good way to get folks thinking about how (or if) they want to be energy-independent. Costs are involved whether you’re energy-independent or getting your electricity from a power company.

Grid-tied is just another way of saying a property is plugged into the local power company's line and is also using solar energy to offset the electric bill, but is still dependent on the company's service. A grid-tied photovoltaic (PV) solar system is a good way to reduce your electric bill, but with the added fees and taxes, you probably won't get the bill down to zero. (This will depend on your utility company and how it accounts for your excess solar production.) You’re also at the mercy of electric rates that are rising faster than grandma's biscuits. If you want to truly be free of those monthly bills, you must go off-grid, meaning you’re cutting the cord with the power company. Despite some struggle in the beginning, going off-grid has its rewards, and could mean the difference between surviving long-term power outages or waking up with no heat, water, or lights.

A middle-of-the-road alternative is the grid-tied solar system with battery backup. (Note that off-grid also requires batteries.) More expensive than grid-tied systems, this option still costs less than the totally off-grid approach. Depending on the size of the backup system, it could carry you through a short-term blackout and reduce your bill when the grid is up.

— Hoss Boyd

The short answer to Lee's question on grid-tied vs. off-grid solar and battery backup systems is that grid-tied means you get your electricity from utility company power lines; off-grid means your electricity comes totally from your own equipment (including batteries); and the latter is a grid-tied solar system with battery backup, and the batteries supply electricity to your property when the grid goes down.

A grid-tied system will provide energy from the solar array only during peak sunlight hours (usually from 4 to 6 hours a day, depending on your location). The rest of the electricity will still come from the grid. This includes nighttime loads and electricity used on cloudy days. An off-grid system has no access to the grid at all, so energy use is limited to what the system can produce and store. A grid-tied solar system with battery backup adds a lot of flexibility, offering self-reliance at night, on days without sun, and in events of grid failure.

Another safeguard for off-grid systems is tying in an emergency generator. When the battery bank is depleted and neither solar energy nor grid power is being produced, you can switch on a generator to charge the batteries and keep the system operational.

— Kerena Reese

Hoss and Kerena will answer queries on energy subjects in upcoming issues. Email them at [email protected] with "Gone Off-Grid" in the subject line.

Hoss Boyd is founder, president, and CEO of TeraVolt Energy. Kerena Reese is an independent energy engineer. They’re recognized solar and energy-storage experts. Learn more about TeraVolt Energy at www.TVNRG.com.

Originally published as "Gone Off-Grid" in the June/July 2023 issue of Grit magazine and regularly vetted for accuracy.