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How Many Solar Panels Do I Need to Run a House Off-Grid?

Written by Eddie B. Robinson / Checked by Justin Tucker

how many solar panels do I need to run a house off grid

Have you ever asked yourself if living off-grid is right for you and your family? I know you might have also wondered, how many solar panels do I need to run a house off-grid? Living off-grid is not for everyone, but it is perfect for people who want to contribute to a greener planet.

You can live off the land, fish the waters, and survive on what Mother Nature has to offer. However, let us face it; most of us cannot get rid of modern conveniences from our lives. That is why having a solar system generating power for our most prized electric appliances makes perfect sense.

So, how many solar panels should you get for off-grid living? Let us find out.

How Many Solar Panels Are Sufficient for Living Off-grid?

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The number of solar panels needed for off-grid living depends on your energy requirements, average sunlight exposure, and solar panel type. On average, an off grid solar system small home requires at least 7,000 watts of electricity to run different appliances.

However, you can always focus more on critical appliances to reduce your energy requirements without sacrificing the many benefits of off-grid living. Hence, the first step to determining how many solar panels you need is identifying the must-have appliances in your off-grid home.

The next step requires you to analyze each electric appliance and device’s power requirements, including how long they need to operate every day.

Suppose you computed 5,000 watts as your daily energy requirement. The next step requires choosing the right solar panel. Photovoltaic panels have different energy efficiency ratings, ranging from 10 to 20 percent. It would be best to get a solar panel with a high solar panel cell efficiency rating.

You might also want to check the solar panel’s energy output and the recommended conditions for optimal performance. For example, some solar panels are only efficient when the sun shines brightly in the sky. Other solar panels maintain their efficiency even on cloudy days.

To determine how many solar panels you need, divide the off-grid home’s power requirements by the solar panel’s wattage rating.

Going back to our example, suppose the only available option in your place is a 100-watt solar panel. In that case, you will need 50 100-watt solar panels to produce 5,000 watts. If you can buy 200-watt solar panels, you will only need 25 solar panels.

Hence, it is safe to assume that the number of solar panels needed for an off-grid system depends on the power requirement and solar panel wattage availability.

The higher the solar panel wattage rating, the fewer solar panels you need. Conversely, using lower-rated solar panels translates to more solar panels needed to supply energy to the off-grid home.

However, the method I shared above is a rough estimate of the number of solar panels needed for your off-grid lifestyle. If you want a more refined calculation, you might want to do a little math.

The formula requires you to divide your monthly electric usage by the monthly peak sunlight hours in your place. You can then multiply the result by 1,000 before dividing the product by the solar panel’s power rating.

The first step is to determine the number of kilowatt hours you will consume every month. If you intend to use all electrical appliances in your off-grid living, you can look at your current electric bill to know your energy usage. Let us say you need 1,000 kWh monthly.

The second step is to learn the daily peak sunlight hours in your area. For example, California has an average peak sunlight hours of 5.82, while Colorado has 5.37 and Arizona has 6.5. Let us assume you live in Arizona. Hence, you have 195 peak sunlight hours per month (6.5 x 30 days).

The third step is to divide 1,000 kW by 195 to get 5.128 kW. Multiplying this number by 1,000 gives us 5,128 watts.

The final step is to divide 5,128 watts by the solar panel’s power rating. If you use 250-watt solar panels, you need 21 solar panels (5,128 watts ÷ 250 watts = 20.512). Using 300-watt solar panels will lower the solar panel requirement to 17 (5,128 watts ÷ 300 watts = 17.093).

If you decide to use 100-watt panels, you will need about 52 solar panels (5,128 watts ÷ 100 watts = 51.28).

How Different Is an Off-grid Solar System From an On-grid System?

As the name suggests, on-grid solar systems connect to an electric power grid supplied by a distributor or utility. You get to use energy from your solar panels to run electrical appliances and fixtures during the day.

When there is no sun or the solar panels do not function optimally, you can rely on the grid connection to supply your home’s power requirements. There is no need for a battery bank, and you get to save on electric bills by using solar-drawn power.

The problem with an on-grid solar system is that you cannot run it during blackouts or power outages. It would be unsafe to do so. Power from the solar system can move to the grid lines, undermining workers’ safety.

On the other hand, solar panels for off-grid living do not connect to an electrical grid network. Your home is dependent on the solar system’s energy generation and the battery’s electrical storage capacity.

What Factors Should I Consider in Setting Up an Off-grid Solar System?

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Before living off-grid, consider the amount of solar power for off grid living you need, the type of PV system, and the battery size. Read below for more information.

Energy Needs

Solar panels consist of photovoltaic cells that absorb solar energy and convert it into usable electricity. That is why it is best to determine your off-grid home’s energy requirements before buying solar panels.

I recommend using an off-grid solar system sizing calculator to determine solar energy requirements. This software automatically computes your home’s energy needs using the information you input into the program.

In general, the software requires you to enter the following information.

  • Number of watts required to run all appliances and devices
  • Number of hours you run the appliances
  • The average number of hours of continuous sunlight
  • Charge controller efficiency

In turn, the solar sizing calculator will give you an idea of the following.

Such information should give you a head-start in setting up an off-grid solar system.

Must-have Electric Appliances and Devices

Two things are worth considering when living off-grid. First, you must determine the power requirements of each appliance you have. Second, it would be best to evaluate which devices you can and cannot live without.

For example, some families cannot live without a clothes dryer, while others find air-drying on a clothesline sufficient. Some households might want to ditch the washing machine for good old-fashioned handwashing.

Solar Options

Some families prefer to buy different solar system components from various retailers. For example, they might want to buy solar panels from one company, a charge controller from another brand, and connecting cables from elsewhere.

While buying individual components is acceptable, it is better to get a solar system kit. The kit already includes everything you need to set up a solar system in your off-grid home. These kits can come with different solar panel sizes, from 50 watts to 4,500 watts.

Power Storage Solutions

The principal difference between an off-grid and on-grid solar system is the former’s battery requirement. You will need a deep cycle battery to store the energy the solar system generates, so you will have something to use at night or when the solar system is inoperable.

Tiny homes can survive on a 12-volt battery system. However, if you need 1,000 to 3,000 watts of electricity every day, a better option is a 24-volt deep cycle battery. Off-grid households with energy expenditure exceeding 3,000 watts should consider a 48-volt system.

It would also be best to check how many watts the battery can store. A household of four can live comfortably with a 4 kWh to 8 kWh deep cycle battery. You can always add more if you must.

Conclusion

Now you know how to find the answer to the question, “how many solar panels do I need to run a house off-grid?” Everything depends on your energy requirements and the solar panel’s power rating. In general, the higher the solar panel’s wattage, the fewer the number of panels you need.

Of course, other factors can also impact an off-grid solar system. The solar panel’s efficiency, the location’s peak sunlight hours, and battery storage can also affect how.

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