How Many Solar Panels Do You Need to Live Off the Grid?

To calculate how many solar panels you need to live off the grid requires understanding your energy consumption patterns, your location's solar resources, and system inefficiencies. Let's break down each step, so you know what to look out for when sizing your solar system.

#1. Assess Your Energy Needs

Examine your current electricity bills to see how many kilowatt-hours (kWh) you consume. If you're planning a new off-grid home, create a list of every electrical device, noting its wattage and daily usage hours. 

Also, energy-efficient appliances are essential. An efficient refrigerator might use 300-400 kWh annually, while older models consume three times that. LED lighting and mindful usage patterns can cut overall energy needs considerably. Furthermore, don't forget seasonal variations—heating and cooling dramatically shift consumption throughout the year.

Most importantly, design your system based on highest consumption periods rather than averages. In this way, you won't run short when you need power most.

#2. Estimate the Available Sunlight Hours

The amount of sunshine your location receives directly impacts how many solar panels you'll need. A home in Arizona with 6-7 hours of peak sunlight daily will require fewer panels than an identical home in Washington State that might only get 3-4 hours during winter months.

Peak sunlight hours refer to the equivalent number of hours per day when solar irradiance averages 1,000 watts per square meter. Even though the sun might be up for 12 hours, you might only get 5 peak sun hours because morning and evening sun hits panels at less optimal angles.

You can find average peak sun hour data through various online resources and solar calculators. For example, the National Solar Radiation Database provides detailed information on geographic coordinates and peak sun hours. 

#3. Factor in the Solar Panel Efficiency

The conversion efficiency of modern monocrystalline solar panels is between 17-22%. Higher efficiency panels cost more upfront but require less roof space and fewer panels overall to achieve the same power output.

For instance, a 400-watt panel producing at rated capacity for one hour generates 400 watt-hours (0.4 kWh) of electricity. However, panels rarely operate at maximum output in real-world conditions. Weather conditions, shading, dust accumulation, and sunlight angle all affect actual production.

Also, you need to account for system losses. Inverters typically operate at 94-96% efficiency, wiring introduces 2-3% losses, and battery charging/discharging involves efficiency losses—80-85% for lead-acid, 90-95% for lithium. To account for these real-world factors, multiply your calculated panel needs by 1.25 to 1.3. This buffer ensures your system can deliver needed power despite inevitable losses.

#4. Incorporate Battery Storage and Off-Grid Essentials

Battery storage for off-grid systems requires careful consideration since you're entirely dependent on stored energy when the sun isn't shining. The standard approach is sizing your battery bank to provide at least two to three days of autonomy.

Using our 27.4 kWh daily example, three days of autonomy requires 82.2 kWh storage capacity. However, you shouldn't discharge batteries completely. Of course, you need to account for the battery type.

The table below compares lead-acid vs. lithium (LFP) batteries:

Furthermore, you need a hybrid inverter as well. This is essential for off-grid systems as you need to manage both solar input and battery charging.

#5. Calculate the Number of Panels

To see how many panels are needed, we’ll use our example household which consumes 27.4 kWh daily in a location with 5 peak sun hours, and uses 400-watt panels. 

Here's how to calculate the optimal number of solar panels:

• Divide the daily watt-hours by peak sun hours: 27,400 ÷ 5 = 5,480 watts needed at 100% efficiency
• Apply a 1.25 derating factor for losses: 5,480 × 1.25 = 6,850 watts total system size. 
• Divide the total system size watts with panel watts: 6,850 ÷ 400 = 17.1 panels, rounding up to 18 panels for a 7,200-watt (7.2 kW) array.

Consider adding even more capacity—perhaps 20 panels—for additional margin during cloudy periods or increased consumption. 

What's the Cost of an Off-Grid Solar System?

The financial investment for going off-grid depends on your system size, component quality, location, and installation complexity. A complete off-grid solar system typically costs between $30,000 and $60,000 for an average home in the U.S. However, smaller cabins might get by with systems under $20,000, while large homesteads with high energy demands could easily exceed $100,000.

Let's break down the major cost components: 

• Solar panels. Quality panels run about $0.50 to $0.80 per watt, so a 7,200-watt array would cost $3,600 to $5,760. However, panels are somewhat the cheapest component (roughly 20-30% of total system cost).
• Battery storage. This typically consumes the largest portion of the budget—often 40-50% of total costs. A lithium battery bank with 100 kWh capacity might cost $40,000 to $60,000, while lead-acid alternatives could reduce this to $20,000 to $30,000, though they'll need replacement much sooner.
• Inverter and charge controller. Together these might account for 10-15% of costs, typically ranging from $3,000 to $8,000 depending on system voltage and power handling capacity.
• Mounting hardware, wiring, disconnects, and other components. These can add another 5-10% to the overall cost.
• Installation labor. This is often 15-25% of the project cost if you hire professionals. However, many off-grid enthusiasts choose DIY solar system installation, which requires electrical knowledge but can save thousands. 
• Ongoing costs. Batteries eventually need replacement. Lead-acid batteries might last 3-5 years, while lithium batteries can go 10-15 years or more. Backup generators add both upfront costs ($1,000-$5,000) and ongoing fuel expenses.

How to Know If Off-Grid Is Right for You?

Deciding whether to go off-grid isn't just a technical calculation, but a lifestyle choice that requires honest self-assessment about your priorities, capabilities, and expectations. While off-grid solar can bring freedom and sustainability, it requires realistic expectations and self-awareness. 

Here are four key factors to consider:

1. Location and access. If you’re building in a remote area where connecting to the grid costs tens of thousands, off-grid solar often makes financial sense. Even in areas with grid access, many people choose independence for philosophical reasons—self-sufficiency, environmental values, or freedom from utility companies.
2. Energy awareness. Living off-grid means paying closer attention to power use. You’ll need to manage high-draw appliances and sometimes adjust usage to sunny days when batteries are replenished. This doesn’t mean discomfort—many off-grid homes are fully modern—but it does require a mindset shift.
3. Financial considerations. Beyond the upfront cost, consider long-term savings. Factor in battery replacements and compare system costs to utility bills over 20–25 years. Off-grid systems often pay for themselves in 10–12 years in areas with high electricity costs, but in others, the motivation may be more about values than ROI.
4. Realistic energy needs. Off-grid systems can power modern conveniences, but efficiency matters. Inefficient appliances or wasteful habits drive up costs. Local weather also plays a role—consistent sunshine makes off-grid living much smoother than cloudy climates.

If you’re serious about off-grid solar, professional advice can save time and money. At Portable Sun, we specialize in complete off-grid systems—panels, inverters, and battery storage from trusted brands like EG4 Electronics, Growatt, Hyperion, and BigBattery. Our experts help design solutions tailored to your location, budget, and lifestyle.

Final Thoughts

Determining how many solar panels you need to live off-grid requires careful consideration of your energy consumption, location, budget, and lifestyle goals. While the calculations might seem complex at first, breaking them into manageable steps makes the process straightforward. Most off-grid homes need between 15 and 30 solar panels, depending on their energy needs and available sunlight.

Remember that successful off-grid living combines proper system sizing with energy efficiency and realistic expectations. Investing in quality components from the start saves money in the long run. Take your time with the planning phase, consult with knowledgeable suppliers like Portable Sun to achieve true energy independence.

How Many Solar Panels to Live Off Grid FAQ

#1. Is 10 kW enough to run a house?

A 10 kW solar system can absolutely run many homes, generating roughly 30-50 kWh daily depending on location and sunlight hours. This covers typical household needs for efficient homes, though energy-intensive lifestyles or large properties might require more capacity. Pair it with adequate battery storage for reliable off-grid operation.

#2. How many solar panels are needed to power a 200 sq ft house?

A 200 square foot tiny house typically needs only 1,000-2,000 watts of solar capacity, translating to 3-5 panels depending on efficiency and consumption. Small spaces naturally use less energy, especially with LED lighting, efficient appliances, and mindful usage. Battery storage requirements are also proportionally smaller.

#3. What types of solar panels are best for off-grid systems?

Monocrystalline solar panels work best for off-grid systems due to their higher efficiency and better performance in low-light conditions. Brands like Hyperion, REC, and others available through Portable Sun offer excellent reliability. Prioritize panels with strong warranties and proven track records in demanding applications over absolute lowest cost.