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I hope that using my family’s data and writing about picking our residential electricity rate plan has made the process more accessible, but I recognize that what’s right for me is not necessarily right for you. To provide broader guidance, I asked people I know to share their hourly energy use data with me and developed five case studies that differ from my own.
For each case study, I’m using data (and Georgia Power rate schedules) from the same period I used for modeling my family’s electricity use (Feb 2022 – Jan 2023). Need a refresher on electric rates and bill charges; how electricity is used at home; the different Georgia Power rate plans; or the impact of going solar? Previous posts in this series have you covered.
As you look through the electric rate modeling results for these case studies and their different electricity end uses, I encourage you to evaluate how closely any of these case studies fit your situation. They are arranged from the lowest use customer to the highest. I promised my volunteers to protect their identities, so everyone got a codename.
Before diving into the case studies, let’s talk about what I believe to be the two most important values affecting these results: the customer’s level of electricity use and the way the customer uses electricity, expressed in terms of their load factor.
As these case studies reflect, the lower use customers tended to do best on the Standard Residential rate and poorly on Smart Usage. The Standard Residential rate has lower fixed charges (i.e., only a basic service charge) with a higher energy charge. Under a tiered rate like the Standard Residential, more of the costs are volumetric and follow the basic rule of “use less, pay less,” which gives a clear advantage for low use customers.
Demand rates like Smart Usage behave a little differently. With a demand charge on top of a basic service charge, Smart Usage has higher fixed (or close to fixed) charges. While this rate plan features different energy charges for on peak and off-peak use, they are lower energy rates on average. Rates with higher fixed costs tend to put low-use customers at a disadvantage and benefit high-use customers. That appears mostly consistent with my results. The exception is Joan, who I talk about in Case Study E.
The other important variable here is load factor, which reflects patterns of electricity use. Load factor is an industry standard way of measuring how a customer uses electricity (0-100%). “Peaky” customers whose electricity use spikes for short periods of time during a billing period have a low load factor, whereas steady electricity users have a high load factor.
As the results will show, Smart Usage appears to work well for above average electricity users, particularly ones that manage to use electricity in a steadier way (i.e., they have higher load factors). Otherwise, the Standard Residential rate tended to yield the lowest annual bill. Again, Joan (Case Study E) bucks this trend with her all-electric home. Now, let’s look at how the different variables play out for all five of our Georgia Power customers.
Roger lives in a 2,100-square-foot single-family home in Atlanta built in the 1920s. He cools his home with two electric central AC units (downstairs and upstairs zones) but heats his home and makes hot water with natural gas appliances. Otherwise, Roger’s electric end-uses are common, such as refrigeration, lighting, dish and clothes washing, and plug loads. He does not charge an electric vehicle (EV).
Roger is a low-use electricity customer. His average monthly electric use during the period was 350 kWh per month, about a third of the use for the average for Georgia Power residential customer.
Roger is on the Nights & Weekends rate plan, but he might save about 6% on his annual electric bill by switching to Standard Residential. It’s worth noting that Roger’s current rate plan results in the lowest monthly bill in eight of the twelve months but significantly higher bills than the Standard Residential rate in the four summer months.
Candler lives in a 2,200-square-foot single-family home built in 1930 in Atlanta’s Candler Park neighborhood. Like Roger, he cools his home with two electric central AC units (downstairs and upstairs zones); heats his home and makes hot water with natural gas appliances; and has common electric end-uses that don’t include EV charging.
Candler’s average monthly electric use during the period was 1,145 kWh per month, just slightly above the average for Georgia Power residential customers.
Candler is on the Standard Residential rate plan and will likely benefit from staying on it. Standard Residential yields the lowest total bill for him, though the Nights & Weekends rate plan is within a couple of percentage points. While this is true when looking at the whole year, it’s not the case each month.
For Candler, the Nights & Weekends rate plan produces lower monthly bills in eight months of the year (non-summer months), and the Plug-In EV rate plan produces lower bills in the other five months. But the savings Candler achieves in the summer months on the Standard Residential rate plan offset those off-peak monthly savings.
Sandy lives in a 3,600-square-foot single-family home in Sandy Springs that was built in 1984. As in Case Studies A and B, Sandy cools his home with two electric central AC units (downstairs and upstairs zones) but heats his home and makes hot water with natural gas appliances. Sandy’s electric end-uses are common, and he does not charge an EV.
His average monthly electric use during this 12-month period was 1,270 kWh per month. This is about 15% above the average monthly use among Georgia Power’s 2 million+ residential customers.
Sandy is a higher load factor customer. His average monthly load factor was 27%, while mine was 16%. Given the fact that Sandy’s end uses are like mine, I suspect that his more modern home is easier to cool than my leaky Depression-era home with little insulation.
Sandy is on the Flat Bill residential rate plan. The underlying pricing for Flat Bill is the Standard Residential rate plan—it just offers a different way to pay. He could save about 3% on his bill for the year by switching to the Smart Usage rate plan. Standard Residential does yield the lowest bill in four months of the year (typically low-use “shoulder” months such as Apr-May), but Smart Usage yields the lowest bill in the other eight (higher use) months.
Ben lives in Decatur in a 2,200-square-foot single-family home built in 1950. But in 2009, Ben and his wife completed an extensive renovation of their home that achieved Platinum certification under the Leadership in Energy and Environmental Design (LEED) rating system. Their LEED Platinum home incorporates many efficiency measures, such as triple-pane low-e argon windows, LED lighting, spray foam insulation, ENERGY STAR appliances, and a high efficiency gas furnace and air conditioners. I think these “shell” improvements contribute to the family’s high load factor.
Ben’s end-uses are more diverse than in most homes. His family cools the home with two electric AC units (central AC system for primary living spaces and mini split ductless AC in the basement bedroom). They heat the primary living space with a natural gas furnace and heat the basement bedroom with an electric heat pump (the mini split). Ben and his family make hot water with a solar hot water heater, but the system does have an electric backup heater that contributes to their electric use. They cook with an electric stove, but the cooktop is gas. Even the family’s clothes washing is dual fuel—their clothes washer is electric but their clothes dryer heats with gas.
While most of their other electric end uses are common, they do have dehumidification systems in the attic and basement and a radon mitigation system with a fan. Ben’s family also operates multiple refrigerators and freezers, and the home has electric heated floors in the bathrooms on a timer.
Ben’s average monthly electricity use during the period was 1,480, almost 50% more than the average Georgia Power customer. Their family is on Georgia Power’s Standard Residential rate. Unlike most of the other people featured in this case study, Ben could save significantly by switching to the Smart Usage rate—approximately 16% on their annual electricity costs. Why? I think the answer has two parts. Ben is a higher-than-average electricity user, which takes advantage of Smart Usage’s lower per-kWh energy charge. More importantly, though, I believe Ben’s efficient home dramatically increases his load factor.
Joan lives in a 2,600-square-foot, all-electric townhome in the Atlanta suburbs built in 1974. Joan heats and cools her home with two electric heat pump units. Otherwise, Joan’s electric end-uses are common. She doesn’t charge an EV.
Joan is a high-use electricity customer. Her average monthly use over the period was 1,600 kWh, about 60% higher use than the average Georgia Power customer. This fits for an all-electric home.
Joan is on the Standard Residential rate plan, and it makes sense for her to stay on it since it produces the lowest annual electric bill. But it does not produce the lowest monthly bill across all months. Nights and Weekends, which was only slightly higher in terms of annual cost, produces slightly lower monthly bills in six of the 12 months.
Smart Usage produces summer bills either comparable to or cheaper than the Standard Residential rate plan for Joan. I thought Smart Usage might be best for an all-electric home like hers, but surprisingly, it turned out to be the most expensive on an annual basis. Smart Usage produces dramatically higher winter bills for Joan’s home, in part due to very high demand charges in those months. This proved to be too costly.
Joan’s monthly load factor in the summer months averages nearly twice her monthly load factor in the winter months. In other words, she has high peak demands in the winter months (kW) with lower average monthly use (kWh). Smart Usage typically benefits high load factor use while punishing low load factor use.
Overall, the Standard Residential rate proved the most cost-effective rate for my family and for three of the five customers profiled. In one case, the Smart Usage rate came out slightly ahead. In the case of Ben, Smart Usage came out significantly ahead.
The table below shows the average monthly use and average monthly load factor for each case study subject alongside the rate yielded their lowest annual cost. As noted earlier, Smart Usage works particularly well for above average electricity users with higher load factors that reflect steadier patterns of use. The Standard Residential rate plan otherwise tended to yield the lowest annual bill.
I was disappointed that the energy-only time of use rates (Nights & Weekends and Plug-In EV) didn’t win out for any of these customers. My sample lacked an EV owner, but I still thought one of these rates would be the best fit for someone. In the next and final post in this series, I’ll feature one way these rates might prove the best deal.
I hope the information here helps guide your decision making as you work to get the most bang for your buck from your Georgia Power rate plan. I also hope you’ll continue this journey with me a little further to explore the value of using residential battery systems to save money on your electric bill.
Electric Bills Decoded is Southface Institute’s series exploring how Georgia Power residential customers can use data to help determine whether changing their electricity rate plan can lower their utility bills and offset recent rate hikes. Follow along to understand different types of rates and charges; identify electricity usage patterns; use your data strategically; consider the impact of going solar; explore several case studies; and learn about battery storage as a cost-saving tool. We’re decoding it all!
