If you’ve just purchased a home and are considering going solar, you’re in the perfect position to set things up right from the beginning. But if you’re like most new homeowners, you probably have one big question:
“How do I size a solar system if I don’t even have a full year of electricity bills yet?”
At Supreme Solar and Electric, we help new homeowners make smart, long-term solar decisions—even without 12 months of usage history. The key is knowing what to evaluate when it comes to your energy needs.
This post will walk you through how we do that. We’ll cover:
- How we calculate energy needs without usage history
- How your square footage, appliances, and lifestyle play into sizing
- What to expect based on your home’s size
- Why planning for future usage is essential
- How we help new homeowners make the right solar investment
Let’s jump in.
Step 1: Start with a Load Calculation
When there’s no previous usage history to go off of—like when you just bought the home—we start with what’s called a load calculation.
What is a Load Calculation?
A load calculation is the process of evaluating everything in your home that uses electricity and estimating how much energy it will consume over time. It’s how we forecast your system size when we don’t have real bills to reference.
There are three parts to this:
1. Evaluate Major Electrical Appliances
First, we look at the big power users in the home:
- Air conditioners (How many? Central or split? What size?)
- Electric dryers
- Ovens and ranges (gas or electric?)
- Water heaters (gas or electric?)
- EV chargers
- Well pumps or pool pumps
These are the high-demand items that drastically affect your system sizing. For example:
- A Level 2 EV charger can add 400–500 kWh/month
- A central AC unit in Fresno can run 1,000+ kWh/month during summer
- An electric water heater may use 300–400 kWh/month
The more of these you have—or plan to add—the larger your solar system needs to be.
2. Calculate Square Footage-Based Loads
Next, we look at the size of your home. Even without heavy appliances, every home has a baseline usage that comes from:
- Lights
- Refrigerators
- Garage doors
- TVs and entertainment systems
- Computers, phone chargers, kitchen appliances
These are known as branch circuit loads, and their impact is largely based on the size of the home and how many people live in it.
Here’s a rough breakdown of average annual electricity usage based on square footage:
| Home Size | Estimated Annual Usage (kWh) |
| 1,000–1,500 sq. ft. | 12,000–14,000 kWh |
| 1,500–2,000 sq. ft. | 13,000–15,000 kWh |
| 2,000–3,000 sq. ft. | 15,000–18,000 kWh |
| 3,000+ sq. ft. | 18,000+ kWh |
These numbers vary depending on insulation, HVAC efficiency, and how you use the space—but they’re a strong starting point.
3. Factor in Future Electrical Loads
The final step in a load calculation is considering what you plan to add in the future. Solar is a long-term investment—so your system should reflect not only what you need today, but also what you might need 5 to 10 years from now.
Common future loads include:
- Adding an EV
- Switching from gas to electric appliances
- Installing a pool or spa
- Adding a detached unit or ADU
- Going all-electric for heating or water
You don’t have to do everything today, but we highly recommend oversizing the system slightly now, so you’re not stuck underproducing later.
What About Lifestyle and Habits?
Beyond the technical specs, we also consider your daily habits and preferences. These have a big impact on how much electricity you’ll use.
Some key questions we ask:
- What temperature do you keep your AC at in the summer? 72 or 78 degrees can make a huge difference in energy use.
- Do you cook frequently with an oven or electric stove?
- Is your dryer gas or electric?
- How many people live in the home?
- Do you use energy-intensive appliances like air fryers, space heaters, or large entertainment systems?
These are all inputs that help us tailor the system to your lifestyle, not just your floorplan.
Why Wait for Usage When You Can Calculate Now?
A lot of new homeowners wait 6–12 months to “see what the usage looks like” before installing solar. That’s a valid approach—but it comes with a cost.
Here’s why we recommend doing it sooner:
- You’re already paying high PG&E rates—why wait to start saving?
- Interest rates and incentives may change while you wait
- You can avoid installation delays by acting before summer demand spikes
- Your contractor can base the system on actual home specs and behavior, not guesswork
At Supreme Solar and Electric, we’ve installed solar on thousands of homes in Fresno and the Coachella Valley. Based on your area, the year the home was built, and your major appliances—we often know exactly what it takes to offset your bill even without 12 months of data.
What We Do at Supreme Solar and Electric
When we work with new homeowners, here’s what our process looks like:
- We evaluate your electrical panel and determine if it can support the system size
- We walk through your appliances—what’s gas, what’s electric, and what’s planned
- We factor in square footage and general usage assumptions based on similar homes
- We discuss your lifestyle, usage habits, and comfort preferences
- We design a custom system with or without batteries based on that info
We’ve seen enough homes across Fresno and the Coachella Valley to know what works—and how to size systems accurately even without a single utility bill.
What Happens if You Undersize?
Here’s a real example:
A homeowner in Fresno installs a 5 kW system that offsets 80% of their current usage. One year later, they add an EV.
- Their system can’t keep up
- Their battery runs out early
- They start pulling from the grid every night
- Their True-Up bills come back
The lesson? It’s better to size for tomorrow, not just today.
Conservative vs. Aggressive Sizing: What’s the Right Strategy?
When designing a system for a new homeowner, you have two main approaches:
1. Conservative Sizing
You size the system based on current appliances and square footage, with maybe a 5–10% buffer. This keeps the system smaller and less expensive, but may fall short if you add new loads down the road.
2. Oversized Sizing
You build in a 15–20% buffer for future use. This raises the cost slightly today, but protects you long-term. You’re less likely to owe the utility anything, even if your usage increases.
Our recommendation? If you plan to be in the home for a long time, or you expect to electrify more things (like EVs), oversize your system now. It’s easier and cheaper than retrofitting later.
Final Thoughts: Don’t Let No Usage History Hold You Back
Being a new homeowner puts you in a great position to go solar—you get to build the right system from the ground up, without being stuck with someone else’s energy habits.
By doing a proper load calculation, looking at your square footage and appliances, and planning for the future, you can build a system that:
- Saves you thousands every year
- Offsets 100% of your power usage
- Prepares you for electrification
- Shields you from rising utility costs
- Adds value to your home from day one
Ready to Design the Right System for Your New Home?
We’ve helped hundreds of new homeowners go solar the right way—with accurate sizing, clean installs, and future-proof system designs.
Contact Supreme Solar and Electric today for a free proposal, and let’s build your home’s solar future—starting now.
