Most Horry County residents don’t give much thought to where their electricity comes from until it stops arriving. That’s a reasonable position — the grid has been reliable enough for long enough that it functions as background infrastructure rather than a daily concern.
That picture has been shifting over the past decade, and understanding why is useful context for homeowners evaluating standby power. This isn’t a case for alarm. It is a straightforward look at what has changed in how Horry County receives its electricity, what the utility serving this area knows about its current limitations, and what it is actively doing to address them.
Where Horry County’s Power Comes From
Santee Cooper — South Carolina’s state-owned electric and water utility — supplies Horry County’s electricity, both directly to retail customers, and indirectly through the Horry Electric Cooperative. Santee Cooper owns and operates the transmission infrastructure that moves power from generating stations to local distribution lines, which then deliver it to individual homes and businesses.
As of early 2025, Santee Cooper serves approximately 184,500 customers directly, with Horry County accounting for roughly 85% of that base. The Horry Electric Cooperative adds thousands more. According to U.S. Census Bureau data, the county’s population has grown from approximately 298,000 in 2014 to over 413,000 in 2024 — a 38% increase in ten years — and that growth continues. New residential customers are connecting to the system faster than at any previous point in the county’s history.
What Changed in 2012
For most of Horry County’s modern history, the Dolphus M. Grainger Generating Station near Conway provided local generation capacity. The Grainger plant was a 170-megawatt coal-fired facility that contributed directly to the power supply serving this region.
Grainger closed in October 2012, primarily due to new requirements under the Clean Air Act. With its closure, Horry County lost its closest local generating source. Power now travels to the area primarily from Santee Cooper’s Cross generating station in Berkeley County, and Winyah Generating Station in Georgetown County — both located outside Horry County, connected via transmission lines that cover significantly more distance than Grainger’s local generation required.
Longer transmission paths create more points at which a storm, equipment failure, or accident can interrupt service to a larger number of customers. This is not a criticism of the system or those who operate it — it is a fundamental truth of how transmission infrastructure works.
Winyah’s Scheduled Retirement
The picture changes further in the coming years. Santee Cooper has announced the retirement of Winyah Generating Station, currently scheduled for 2028. Winyah is one of the primary sources currently supplying power to Horry County and the surrounding region.
Santee Cooper’s own planning documents acknowledge the implications directly. In describing the transmission projects required to manage Winyah’s retirement, the utility states that without infrastructure upgrades, potential violations “could pose serious risk to the transmission system reliability in the area and result in the need to curtail large amounts of load.”
What Santee Cooper Is Doing About It
The retirement of Winyah and the sustained load growth from Horry County’s population boom have prompted Santee Cooper to undertake two major transmission infrastructure projects directly serving this area.
Marion–Conway 230kV Transmission Line Santee Cooper is constructing a new 230kV transmission line approximately 34 miles in length from Marion to Conway, rebuilding an existing 115kV line as a double circuit along existing right-of-way. The project addresses thermal loading and voltage violations identified in eastern Horry County under contingency conditions — meaning conditions that arise when part of the system is under stress or has failed. Construction was scheduled from May 2022 through December 2025.
Marion–Red Bluff 230kV Transmission Line A second, larger project is underway for northern Horry County. This line will run approximately 50 miles, combining rebuilt existing lines and new construction, and it is designed specifically to provide the transmission reinforcement required as Winyah retires. Construction is scheduled from June 2024 through December 2028.
Together, these two projects represent a significant and ongoing investment in the transmission infrastructure serving Horry County. They are Santee Cooper’s answer to the reliability gap created by population growth, Grainger’s closure, and Winyah’s impending retirement. When complete, they will substantially improve the county’s transmission capacity and reduce the voltage and thermal risks the utility has identified.
The work is real, it is underway, and it reflects a utility that has identified the problem and is investing in the solution. It also reflects the fact that Horry County is in a transition period — the old infrastructure is being replaced, and the new infrastructure will not be fully in place until the end of the decade.
The December 2022 Rolling Blackouts
On December 24, 2022, Santee Cooper and Horry Electric implemented rolling blackouts across the region — a controlled, deliberate reduction in power delivery to prevent wider grid failure during an extreme cold weather event. Duke Energy, Santee Cooper, and Horry Electric all participated, with more than half a million customers across the Carolinas affected at some point during the event. It was described at the time as an unprecedented measure for this area.
Rolling blackouts of this kind are strategically managed interruptions. They are preferable to an uncontrolled grid failure, and they reflect utilities making responsible decisions under difficult conditions. They are also evidence that the grid serving Horry County can reach the limits of its capacity under sufficient stress.
Growing Demand
Horry County’s load growth is not only residential. The expansion of electric vehicles adds demand to a grid that was sized for a smaller population using less electricity per household. Santee Cooper has active EV programs and rate structures in place for this customer category, which reflects that this growth is expected and being planned for.
The combination of a growing population, higher per-household energy use, Winyah’s looming retirement, and transmission infrastructure that is being upgraded but is not yet complete, creates a period of transition. The grid is not failing. It is, however, under more pressure than it was a decade ago, and that pressure is documented and acknowledged by the utility responsible for managing it.
What This Means for Horry County Homeowners
None of the above is cause for alarm, and it should not be read as a prediction of frequent outages or widespread failures. Santee Cooper’s distribution reliability has historically ranked among the best in the country, and the investments underway reflect a utility working to maintain that standing as conditions change.
What it does mean is that the assumptions some homeowners carry about grid reliability — based on decades of relatively stable service from a system that looked different than it does today — are worth revisiting. The grid is in transition. The transition is being managed. And for homeowners evaluating whether standby power makes sense, understanding the current environment provides accurate context for that decision.
A standby generator does not depend on the grid to function. When utility power fails — whether for minutes or days, from a storm or from system stress — a properly installed standby system starts automatically and runs until utility power is restored. For Horry County homeowners who have lived here long enough to experience the December 2022 blackouts, a multi-day post-hurricane outage, or an extended winter storm event, the value of that independence is concrete rather than theoretical.
Further Reading
- Hurricane Season Generator Checklist
- Hurricane Season Starts June 1
- Remote Monitoring for Standby Generators
- Residential Generator Maintenance
- Generator Services in Horry County
- Do You Require Reliable Power For Home Medical Needs?
Contact Cooper Electrical Services
Call 843-945-1627 or use our contact form.
