How Summer Peak Rates Affect Home Energy Costs
Summer energy bills tend to be the highest of the year for most New Mexico households. Part of that is simply the volume of electricity used — air conditioning running more hours, fans and coolers running overnight. But part of it may also be about when that electricity is used, not just how much.
If you're on a time-of-use rate plan — or if you have solar or battery equipment that could interact with one — understanding how summer peak pricing works can help you ask better questions of your utility and your electrician.
What Peak Demand Pricing Is
Electricity is not equally expensive to produce and deliver at all hours of the day. On a summer afternoon, when households and businesses across the grid are simultaneously running air conditioning, the demand on the electrical system peaks. Utilities respond by bringing on more expensive generation sources and straining their distribution infrastructure.
Time-of-use pricing passes some of that real cost along to customers. During peak hours — often roughly midday through early evening on weekdays during summer — the per-kilowatt-hour rate is higher. During off-peak hours, often late evening through early morning, it's lower.
Some rate plans also include demand charges for commercial accounts, or tiered peak periods where rates step up as the day progresses. For residential customers, TOU rates are the most common form of time-varying pricing.
How This Interacts With Solar
Homeowners with solar panels may notice an interesting effect with TOU rates: their solar production peaks roughly around midday, which often overlaps with the beginning of the peak pricing window. That means solar is producing power right when grid electricity is most expensive — which is generally favorable if your system is sized to cover those loads.
However, by late afternoon — when rates may still be in the peak window but the sun is lower in the sky — solar production may start declining while cooling loads remain high. This is the period when a battery system can bridge the gap.
How Battery Systems Interact With Summer Peak Rates
A home battery system configured to work with TOU rates can do something conceptually simple: charge during cheap off-peak hours and discharge during expensive peak hours. In practice, this means the battery charges from the grid overnight when rates are low, then supplies power to the home during the afternoon peak window instead of drawing from the grid at high rates.
With solar added to the picture, the battery may also charge directly from solar production throughout the day, keeping the stored energy topped up for the afternoon peak period.
The degree to which this strategy is practical depends on your home's loads, your battery's capacity, and how your utility's TOU rate schedule is structured. Your electrician can help you understand the equipment side; your utility is the right source for rate schedule specifics.
Questions to Ask Your Utility
Before making decisions about solar or battery equipment based on rate assumptions, it's worth confirming a few things with your utility:
- What is the current TOU rate schedule, and how are peak hours defined in summer?
- Are there different rate options for homes with solar or battery systems?
- Does exporting stored battery energy back to the grid work differently than exporting solar energy?
- Has the rate structure changed recently, and when is it next scheduled for review?
Rate structures can and do change. Building a significant capital investment around assumptions that may shift in a few years is worth thinking through carefully.
Questions to Ask Your Electrician
On the equipment side, relevant questions include:
- Is the battery system I'm considering compatible with TOU scheduling?
- How does the system decide when to charge from solar versus from the grid?
- What monitoring will I have to see whether the TOU strategy is actually working?
- Is there anything about my home's loads or panel configuration that would affect how well this strategy works?
Thinking About Your Summer Energy Costs?
If your summer bills have been higher than expected and you want to understand whether battery backup or solar could help, request a quote and we'll talk through what makes sense for your home.