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How Many Solar Panels To Run A House Off Grid

By Benjamin Strusnik January 14, 2022

How Many Solar Panels To Run A House Off Grid

In our current climate-conscious society, and with the increasing affordability of solar energy, many people are opting for a way of life that lessens their carbon footprint and saves money at the same time.

But would it be possible to use solar panels to run your house off-grid? And just how many solar panels would be needed for such a lifestyle?

How Many Solar Panels Does It Take To Run A House Off The Grid?

How Does Solar Energy Work?

Solar energy works by harnessing UV rays from the sun using solar panels. The solar cells are responsible for capturing sunlight for the conversion of UV rays into energy.

The DC (direct current) power created by the panels is then converted into AC (alternating current) power by a solar power inverter. The AC power is then sent to your home to power your appliances.

How many solar panels does it take to run a house off grid

Depending on the type of solar power system you use, any excess electricity it makes is either stored in a battery bank or sent to the electricity grid.

Types Of Solar Systems

There are 3 main types of solar systems; off-grid, on-grid, and hybrid systems.

Off-Grid Solar System

An off-grid system refers to a system that isn’t connected to your utility's main electrical grid. This system harnesses solar power during the day to power your home, and stores any excess energy inside a battery bank.

The excess energy stored inside the battery can then be used during nighttime or whenever there might be a lack of sunlight to convert into electricity.

With an off-grid solar system, your home is completely dependent on solar energy and has no connection to the main electrical grid, which saves you from spending money on electricity or being powerless during blackouts.

Solar panel setups for RVs are generally off-grid systems.

On-Grid Solar System

On-grid or grid-tied solar systems are the most commonly used. This type of solar system has no need for a battery and is tied to the main electrical grid.

When it draws power from the sun, any energy that isn’t used is sent back to the electrical grid in exchange for credit to the owner's utility bill in a process called net metering.

With a grid-tied system, you can shift between using solar energy during the day, and electricity from the grid at night. The downside to this type of solar system is that it doesn’t work during a blackout, the reason being that it could endanger any utility workers who might be doing work on the grid. 

Hybrid Solar System

This type of solar system is tied to the electrical grid while also having a battery bank. This allows the owner to utilize power from both the solar panels and the electrical grid, as well as power from the battery bank in cases where neither is available.

How Many Solar Panels Would You Need To Live Off-Grid?

Before getting a solar system, there are a few important things that need to be considered.

how many solar panels you need run a house off grid

Peak Sunlight Hours

You need to consider the amount of direct sunlight your solar panels might receive. When the sun is at its peak, providing ample energy for your solar panels, it is known as peak sunlight hours.

Peak sunlight hours refer to the times in which the sun is able to provide an average of 1000 watts per square meter. This depends on the size of your equipment, as smaller solar panels tend to be less efficient.

Knowing your region’s peak sunlight hours is important because the amount of direct sunlight your solar panels receive determines the number of solar panels you need.

An area that gets lots of sunlight would provide your panels with sufficient energy, which means the number of solar panels you need won't be that much. On the other hand, if you live in a region that has fewer peak sunlight hours, you will need to compensate for the lack of sunlight by equipping more solar panels.

Electricity Usage

To ensure you get a solar system strong enough to provide your home with power, you need to know how much power your home uses.

Finding this out is simple enough. All you need to do is check your monthly utility bills and take a look at the amount of electricity you spent for the past few months. The amount will appear in kWh (kilowatt-hours).

Knowing how much power your home uses on average will give you an estimation of the number of solar panels you will need.

Roof Space

It's important to note that the number of solar panels you can have may be limited to the amount of space available on your roof. This is particularly important if you’re looking for portable solar panels for camping or a portable solar panel for an electric car.

In addition to roof space, you’ll need to account for the way your roof is angled.

Roof stability is also an important factor, as solar panels can be weighty, especially if you intend to have multiple units. To prevent any future complications, we recommend you call an expert to take a look at your roof to see if it's in well-enough condition to hold the necessary solar panels.

Battery Bank Capacity

Unlike a grid-tied system, off-grid solar systems don't give you the option of switching to your utility's electricity grid in moments when solar energy is unavailable. This could put you in a tough position if you're not properly prepared.

To prevent such a scenario, you need to get yourself a battery bank with enough capacity to provide your home with enough energy not only during the night but on cloudy days as well.

How To Calculate The Number Of Solar Panels You Need

Not everyone uses the same amount of energy, so there’s no single answer for how many panels are needed to power a home separated from the grid.

There’s a simple way to calculate the number of panels you’d need for your home.

As previously stated, you need to take a look at your utility bill to figure out how much energy you use on a monthly basis. Once you have an idea of your electricity usage, you need to find out how many hours of peak sunlight your region gets per month by multiplying the daily peak hours by 30.

how many solar panels you can run a house off grid

Next, divide your monthly electricity usage by your monthly peak sunlight hours.

The average American household uses about 893 kWh per month. If we divide this by the monthly peak sunlight hours of, say, a primarily sunny state like Texas, the equation would look something like this:

893 kWh ÷ 135 = 6.6 kWh

Once you have the value in kilowatts, your next step is to convert the kilowatts into Watts. You do this by multiplying it by 1000.

6.6 kWh × 1000 = 6,614 Watts

To calculate how much solar panels are needed, divide 6,614 kWh by the number of watts your solar system generates per hour. An average solar panel generates about 250 Watts per hour, so we’ll use a 300 Watt system for this example:

6,614 kWh ÷ 300 = 22

So a home in Texas that uses 893 kWh of electricity per month would need about 22 solar panels to sustain itself.

How Much Would An Off-Grid Solar System Cost?

The average cost of a 300-watt solar panel ranges from about $210 to $450 per panel. If we multiply this by the number of solar panels you’d need for a home in Texas that uses 893 kWh of electricity per month (22 panels), the price would range from a minimum of $4,620 to a maximum of $9,900.

Is Off-Grid Solar Energy A Good Investment?

Having an off-grid solar system comes with the obvious advantage of eliminating electricity charges from your utility bill indefinitely. 

The price of installation has become a lot more affordable in recent years, which means it takes less time to save the amount of money equivalent to your initial investment. The average amount of time it takes is about 3 to 5 years.

While being self-sustaining may be an inciting concept for many, the off-grid lifestyle does present its own set of challenges: one of these challenges being maintenance.

Solar Panel Maintenance

Solar panels generally last a very long time, most have an average lifespan of 25 years or so. However, if something happens to your system's battery bank, something that prevents it from powering your home in the absence of sunlight, you might be stuck without power.

For this reason, it's important that your system is well looked after if you're going off-grid.

Even though solar panels generally require little to no maintenance, it would be in your best interest to keep an eye on things, especially when it comes to the battery.

If you own a standard lithium-ion battery, be sure to check the cables and make sure the systems are running smoothly, and that the battery is handling the voltage the way it's supposed to.

Solar panels usually come with a manufacturer's warranty of 5 to 10 years though, with an extended warranty extending as far as an additional 15 years, so you can rest assured that you won't be left out to dry if any issues arise.

Solar Panel Safety

Although solar energy is known to be fairly safe, it's still a device that works with electricity, which is an element that can be unpredictable at times. 

Although minor, there’s still the possibility that something could go wrong.

how many solar panels you have to run a house off grid

Installation

It's generally better to leave these kinds of things to professionals. And if you choose to do a DIY installation, never do it alone, have at least one person with you in case something goes wrong.

Since they draw energy from the sun, they may have electricity built up while you're working on them. To prevent injury, make sure the panels have no charge and keep them covered to prevent them from storing up any energy. 

It's also best to wear insulated gloves and clothing, as well as use insulated equipment to avoid electrocution.

Solar panels are heavy, so you need to make sure that your roof will be able to handle the weight. This is even more important if you're planning on going off-grid by installing multiple solar panels.

Some generator kits, however, are specifically designed to be installed yourself. Portable RV solar panel kits are completely safe and easy to setup on your own.

Surge Protection

Solar Systems, like all electrical devices, are prone to electrical surges. These occur when a high voltage of electricity flows through the circuits, which ends up damaging the device.

A common cause of surges in solar panels is lightning. Considering the nature of solar panels and their exposed positions, it's easy to see why lightning storms might pose a problem. For this reason, it would be a good idea to invest in surge protection devices for your solar system, especially if you live in a region that experiences lots of lightning storms.

Surge protection devices protect your solar system and prevent electrical surges by detecting any extra voltage and diverting its path into a grounding wire, which prevents any damage.

Solar Panel Fire Safety

Electrical devices are prone to fires, and the same goes for solar systems. Solar panels can become a fire hazard due to things such as faulty installation or damaged wiring.

Although solar panel fires are rare, the possibility of a fire occurring is always there. One way to prevent this is to make sure that the solar panels are installed in accordance with the proper safety codes and standards.

Rapid Shutdown Mechanism

A rapid shutdown mechanism was introduced to solar systems as a sort of safety precaution in the event that something goes wrong. The rapid shutdown mechanism allows someone to manually lower the voltage of your solar system in dangerous situations.

This was introduced as a safety precaution meant to keep first responders like firefighters safe. The rapid shutdown mechanism would allow firefighters to safely access your roof in the event of a house fire or similar disaster. 

It is imperative for solar systems to have a rapid shutdown function, and was made an official safety requirement by the National Electric Code (NEC).

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