When you think about switching to solar power for your household, one of the first questions that comes to mind is usually: “How many solar panels do I need?” This is not a simple question, as the answer varies depending on many factors, including your energy needs, the location of your home, the orientation of the roof, and several other elements.
That is why, in this guide, we’ll go through all the key aspects that affect the number of solar panels needed for your household. Using the experience and knowledge of our Portable Sun experts, we’ll clear up the dilemmas surrounding solar energy and provide you with all the information you need to make an informed choice. Let’s jump in!
4 Factors That Determine How Many Solar Panels You Need
In order to determine the optimal number of solar panels needed for a household, you need to consider several key factors, including the following:
#1. Your Energy Consumption
If you want your solar panels to generate enough energy to power your home, you need to consider how much energy you will use. Generally, the bigger the house, the more people live in it and the more energy it uses. However, at the same time, you can reduce energy consumption by using efficient appliances and home systems.
Simply put, the less energy your home uses, the fewer solar panels you’ll need. The most reliable way to know how much energy you need is to calculate your yearly energy consumption. By knowing your annual electricity consumption, you can estimate how much energy your solar system needs to generate to meet your solar energy needs.
#2. Sunlight Hours in Your Location
Your home’s location directly affects the amount of sunlight available to the solar panels. Different geographic locations have different levels of solar radiation, which means the number of panels you need will vary depending on where you live.
More sunny days mean more peak sunlight hours and greater efficiency for the solar panels. So, if you live in a location with plenty of sunlight, you will need a smaller number of solar panels to meet your household’s energy needs.
#3. The Efficiency of Solar Panels
The quality of a solar panel is crucial to its energy production. Choosing the right solar panel size, capacity, and efficiency level will help you reduce the number of solar panels you need to install. Plus, better-performing solar panels will allow you to return your installation investment faster.
More efficient panels can generate more energy per square meter, which reduces the number of panels needed. Most classical panels range from 275W to 360W. If you choose the 275W option, you will definitely need more panels.
In addition, it is always recommended to use a panel manufacturer that has extensive experience and a good reputation and provides reliable certificates.
#4. Roof Angle
The amount of sunlight a roof receives is a key factor in determining whether a roof is suitable for solar panels. Roofs that receive a lot of sunlight are more suitable for solar panels than roofs that are shaded. If your roof is shaded most or all the time, you may not be able to install solar panels at all.
A larger roof offers more space to install solar panels, while the roof's slope can affect the optimal angle of installation of the panels. The ideal angle of inclination of the roof is between 20 and 40 degrees.
It is most effective when solar panels are installed on a south-facing roof, as this allows for maximum exposure to sunlight throughout the day. However, east and west orientation can also be effective with slightly lower yields.
How to Calculate the Number of Solar Panels You Need
To determine your home’s average energy needs, look at your past electricity bills and calculate your average electricity consumption. Make sure you collect electricity bills for a period of at least 6 months to a year. If you live in an area with harsh winters or hot summers, look at a larger sample bill to understand when your electricity usage increases.
Then, calculate how many solar panels you’ll need by multiplying your home’s hourly energy needs by the number of hours of sunshine in your area and dividing that by the wattage of the panels you plan to install.
So, the formula for calculating how many solar panels you need would look like this:
Total energy consumption ÷ Panel wattage × Sunlight hours
Keep in mind that the size of your roof and whether it is shaded will also affect your solar power calculations.
In the USA, a 1 kW solar power system typically generates around 1,200 to 1,500 kW annually. So, bearing that in mind, let's examine a few examples to determine the number of solar panels you might need.
Example:
The Robertson household consumes approximately 8,000kW of electricity annually. Their family house roof is oriented to the south.
In order to calculate the solar power system capacity that would suit the Robertson family, we will first calculate how much energy a 1kW solar system would produce annually. So, if the average production of a 1 kW solar power system amounts to 1,200 kWh per year and the Robertson family consumes 8,000 kWh of electricity, we get the following formula:
System size: 8,000kWh ÷ 1,200kWh/kW= 6.67kW
To determine the number of solar panels needed, we’ll divide the total system size by the wattage of a single solar panel. Let’s assume the Robertson family uses 400 watt (0.4kW) panels:
Number of panels: 6.67 ÷ 0.4kW= 16.67
Naturally, since you can’t install part of a panel, we’ll round the result up to 17 panels.
So, the Robertson family would need 17 panels to install a solar power system covering their annual electricity needs.
How Many Solar Panels Do You Need for Different Setups?
The number of solar panels you need in different setups primarily depends on your electrical energy consumption, sunlight hours, and the solar panels' wattage. So, let’s see the average needs for solar panels for different setups.
#1. Residential Home
The number of solar panels you need for a residential home in the USA may vary significantly due to the differences in sunlight hours in regions. However, let’s say that the average energy consumption in a residential home in the USA is 10,000 kWh per year.
If we apply the calculation we used in the example of the Robertson family, assuming an average of 1,200 kWh per year production per 1 kW solar system and a solar panel of 400 watts, the result would be 21 panels.
#2. RVs
On average, RVs only require about five to seven 400-watt solar panels to meet their daily energy needs, as they typically consume less energy, estimated at 2,000 to 3,000 kWh per year. Keep in mind the different requirements of a solar system for an RV, considering the space limitations.
#3. Off-Grid Cabins
Based on an assumption that off-grid cabins consume 3,000 to 5,000 kWh per year, and considering that they rely entirely on solar power, you would need seven to eleven panels of 200 watts. The more energy-efficient appliances you use, the fewer solar panels you need.
#4. Boats
The size of the boat can vary significantly, but let’s say that, on average, the energy consumption needs of a boat are about 1,000–2,000 kWh per year. Translated into the number of panels, this means you need 2 to 5 solar panels for a boat, depending on your energy consumption, sunlight hours, and exposure.
How to Choose the Right Solar Panels for Your Needs
The best way to choose the right solar panels for your needs is to learn about the different types of solar panels. Most solar panels on the market today can fit into three categories—monocrystalline, polycrystalline, and thin film solar panels.
Each of these types has different properties, so let’s go over their basic characteristics:
Monocrystalline Solar Panels
Monocrystalline solar panels typically have the highest efficiency and power capacity of all solar panels. Their efficiency ranges from 17% to 22%.
The advantages of these panel types are efficiency and aesthetics, while the disadvantage is that their price is higher compared to other solar panel types.
Polycrystalline Solar Panels
Polycrystalline panels, sometimes called multicrystalline panels, are popular among homeowners who want to install solar panels while on a budget. Their efficiency ratings range from 15% to 17%.
The advantage of polycrystalline solar panels is the lower price, while the disadvantages are lower efficiency and aesthetics. This practically means you might need more polycrystalline solar panels than monocrystalline ones, as their efficiency is lower.
Thin Film Solar Panels
Thin film solar panels are usually light and flexible, making installation easy. They are mainly used in large solar systems, such as municipal or industrial solar systems, due to their lower efficiency level.
The advantages of thin-film solar panels are aesthetics, flexibility, and lightweight, while the downsides are low efficiency and a short life span.
Portable Sun offers all three types of solar panels, and our experts are at your disposal to help you make the right choice.
Final Thoughts
While this article can give you a very realistic estimate of how many solar panels you need, if you still don’t feel confident making the decision on your own, don’t hesitate to seek support from solar energy specialists.
Moreover, if you’re interested in a renewable energy system, the best thing to do is talk to Portable Sun experts, who can help you find the ideal solar setup for your unique situation.
Your calculation can be an excellent starting point, and we can help you customize the design of your solar system to match your location and lifestyle perfectly.
How Many Solar Panels Do I Need FAQ
#1. How many solar panels do I need to power my house?
The number of panels you need to power your house depends on your energy consumption, solar panel wattage, and sunlight exposure. In general, an average American home typically uses a solar system made of 10 to 15 solar panels.
#2. Can 4 solar panels power a house?
Yes, you can power a small home with minimal energy usage using 4 solar panels. However, most households require more solar panels to cover their electrical energy requirements.
#3. How many solar panels are needed for 60 kWh per day?
Using the formula: total energy consumption ÷ panel wattage × sunlight hours, and assuming you’re using 300-watt panels and have 5 sunlight hours per day, you would need approximately 40 panels to generate 60 kWh per day.
#4. Can I run my home entirely on solar power?
Yes, you can run your home entirely on solar power by installing an off-grid solar system. Keep in mind that going totally off-grid requires precise calculations of your electrical energy needs and careful planning and investment in solar components like solar battery storage, solar generators, solar inverters, and backup systems.
Disclaimer: The content on Portable Sun is for informational purposes only. Electrical work can be dangerous—always consult a qualified professional. We are not liable for any injuries, damages, or losses from installation or use. Always follow local regulations and safety guidelines when handling electrical components.