Utility rates increase every year. For most homeowners, they are skyrocketing. Severe storms cause frequent blackouts. Across the country, power grids are becoming less reliable. Powering your home should be affordable and predictable. Does a solar and battery system make sense for you? You deserve clear answers before investing.
How many solar panels do I need?
The average U.S. home needs between 15 and 25 solar panels. Using standard 400W panels, this creates a 6 kW to 10 kW system size. Because sunlight availability varies by region, identically-sized systems produce different annual energy output. Available roof space and shading also dictate your final array layout.
The table below shows estimated annual energy production (in kilowatt-hours) for 6 kW and 10 kW systems across major geographic regions, assuming unshaded roofs:
| 6 kW System(15 panels, 400W) | 10 kW System(25 panels, 400W) | |
|---|---|---|
| New England | 7,621 kWh/yr | 12,702 kWh/yr |
| Mid-Atlantic | 7,884 kWh/yr | 13,140 kWh/yr |
| Southeast | 9,724 kWh/yr | 16,206 kWh/yr |
| East North Central | 8,147 kWh/yr | 13,578 kWh/yr |
| West North Central | 9,198 kWh/yr | 15,330 kWh/yr |
| East South Central | 9,461 kWh/yr | 15,768 kWh/yr |
| West South Central | 10,512 kWh/yr | 17,520 kWh/yr |
| Southwest (SoCal, AZ, NM, NV) | 12,089 kWh/yr | 20,148 kWh/yr |
| Mountain West (CO, UT, WY, ID, MT) | 11,038 kWh/yr | 18,396 kWh/yr |
| Pacific West (NorCal, OR, WA) | 7,621 kWh/yr | 12,702 kWh/yr |
What size battery do I need?
Battery size depends on your specific backup goals. Essential home loads like your refrigerator, Wi-Fi, and lights typically require a 10 kWh to 15 kWh system. Whole-home coverage requires 15 kWh to 30+ kWh, especially if you plan to run heavy loads like central air conditioning.
Continuous power ratings, measured in kW (kilowatts), determine how many appliances can run simultaneously. A battery rated under 5 kW handles basic lighting and refrigeration. Heavy power draws can trip smaller systems. Batteries with higher power output, e.g., 10+ kW, can manage the initial power surge required when large motors start.
What is the cost of a solar home system and battery backup?
System prices vary based on your location and roof complexity. At $2.75 per watt, a 6 kW system costs $16,500, and a 10 kW system costs $27,500. At $3.25 per watt, those same systems cost $19,500 and $32,500. Professional battery installations range between $10,000 and $20,000 depending on capacity. Single 5 kWh batteries sit at the lower end of that range. Multi-battery setups for whole-home coverage reach the higher end. Long-term utility savings and local incentives reduce your net cost over time.
Is a solar and battery system worth it for my house?
A combined solar and battery system works like energy insurance for your home. It stores excess solar power generated during the day for use at night. During a power blackout, a battery keeps your lights, refrigeration, and vital electronics running smoothly. Batteries can also lower utility costs by reducing your reliance on expensive peak-hour electricity rates.
Take Control with ASSET
Visit factorcenergy.com today to try the Snapshot, Solar Design, and Battery Sizing tools. For more detail, explore our FAQs on Solar and Battery Fundamentals and System Costs.
We built ASSET (Advanced Solar & Storage Evaluation Tool) to give you independent, home-specific answers in minutes.
- Solar & Battery Snapshot: Run instant solar and battery estimates for bill savings, system production, and payback timelines.
- Solar Design Tool: Drag and drop custom panel arrays directly onto a high-resolution photograph of your roof.
- Battery Sizing Module: Model custom backup plans tailored for essential appliances or complete whole-home coverage.