Solar panels’ popularity has tremendously soared in recent decades. This can be attributed to several factors, such as:
- Environmental campaigns have made people want to reduce their carbon footprint.
- A desire to reduce the ever-increasing energy bills.
- Government incentives to households or businesses with solar systems.
If you are planning to switch to solar energy and ditch the grid system, you could wonder how many solar panels you need to power your home.
While it is challenging to pinpoint a single answer to this question, this guide will give you guidelines for estimating how many solar panels to power your house. Let’s dive into the maths.
If you are wondering How Long Can Solar Panels Last Without Sun? I wrote a whole article that I encourage you to check out.
Factors Determining How Many Solar Panels Needed To Power a House
Different households have different energy needs; however, there are universal factors that dictate the amount you consume.
Here are factors you should consider when calculating how many solar panels to power your house.
1- Your Family Usage
You will need more energy if you have heavy appliances running in your home. This means you need more solar panels to generate enough electricity for your home use.
2- Available Installation Space
How much space is available in your home (on the roof, wall, and ground) where you can install solar panels?
If you have a small roof and cramped space, you can generate only limited energy even if you want more. But if you have a big space to install your solar system, you can generate more electricity to power a house.
3- System Efficiency
Some days will be cloudy, rainy, snowy, and sunny, thus affecting the amount of solar power you can harness. Furthermore, different solar panels have different levels of efficiency.
For instance, monocrystalline solar panels work well in sunny climates. This means you may need more of this solar if you live in a region with changing weather patterns.
On the other hand, polycrystalline solar panels work well in all seasons, but they are expensive.
4- Hours Of Sunlight
You may not have many solar panels if your house is in a region with long hours of strong sunlight.
However, if your residence experiences a shorter duration of sunshine, you may need more solar panels to get the most sun.
5- Your Solar Panels’ Wattage
Most solar panels produce between 150 and 350 watts per panel. If you install low-wattage solar energy, you will need more solar panels to generate adequate energy.
Of course, we assume that you want to use only solar panels as your energy source. But if you plan to use solar panels to supplement the grid system, wattage is not important.
But how do you establish the number of solar panels you need? That takes us to the next session.
How To Know How Many Solar Panels I Need?
You can use a formula with three main factors to know the number of solar panels you need to power a house.
According to EnergySage, these factors are panel wattage, annual energy, and production ratios. What do these terms mean?
1- Annual Energy Usage
Do you know your annual electricity usage? I am talking about the amount of electricity your household consumes in a year.
It is measured in kWh and accounts for power consumed by all appliances, including air conditioning units, air purifiers, lights, freezers, and water heaters.
Data from the U.S. Energy Information Administration (EIA) shows that the average American household consumes approximately 11,000 kWh annually.
2- Your Solar Panel Wattage
You may not notice the difference if you look at the best solar panels from the nearest store.
But here is the truth, solar panels are not created equally. Therefore, it is essential to know their difference and the wattage of the type you want to install.
So, what is solar panel wattage? It is the amount of electric energy your solar panels emit. The average wattage for most solar panels is 300 watts.
3- Production Ratios
You may be wondering what the production ratio means. It is the estimated number of kWh a solar system will generate in one year divided by the total wattage of the panels in the system.
A higher ratio is good news because it signifies that your solar panels are efficient. For instance, if you have a 10-kW system that produces 17kWh of electricity for a year, its production ratio is 1.7 (17 ÷ 10).
This is a good ratio that shows an efficient solar system. It is possible to have higher production ratios in areas with long and consistent days of sunshine.
However, if you live in areas where rain and clouds are common, expect to see a low solar production ratio.
Now let’s do the math to determine the number of solar panels you need to power your home.
Mathematical formula showing how many solar panels you need
Here is the formula:
The number of panels = system size ÷ production ratio ÷ panel wattage.
You can insert the figures we established above in the formula and know how many solar panels you need.
So, the number of panels you need = 11,000 kW ÷ 1.7 ÷ 300W = 21.5
From the calculation, we can deduce that a typical American home will require between 20 and 25 solar panels to generate 100% electricity usage.
If you have different variables, you can insert them into the formula to establish how many solar panels you need to power your home.
Variables To Consider When Using The Formula
Although EnergySage estimates that the production ratio ranges from 1.3 to 1.7 and that average annual energy usage is 11,000 kW, these figures can change depending on your consumer products.
For example, your annual energy need could drastically increase in a household running a heated swimming pool or large air conditioners.
It is vital that you evaluate the products and appliances you intend to run at your home and their energy consumption.
Does The Size Of My Home Determine The Number Of Solar Panels I Need?
Although solar panel dimensions have not changed over the past decade, their efficiency within the same area has significantly increased.
Some manufacturers like SunPower have even reduced the gap between panels and use advanced mounting techniques to keep the solar panel systems efficient, tight, and aesthetically pleasing.
The table below gives you an estimate of the number of panels a home will need depending on your home’s square footage.
| Home Size | 1000 sq. feet | 2,000 sq. feet | 2,500 sq. feet | 3,000 sq. feet |
| Estimated yearly electricity you need | 4710kWh | 9,420 kWh | 11,775 kWh | 14. 130 kWh |
| Number of panels needed | 14 | 29 | 35 | 42 |
The table shows that a larger home space or roof can accommodate more panels and produce more electricity.
How Many Solar Panels Will Support My Common Appliances?
If you evaluate your daily energy requirement for products and household appliances, you may realize that some add-ons can significantly change your monthly use.
They can affect the number of solar panels you should install on your roof. For instance, if you pair your electric car with your solar panels, you reduce your carbon emissions. However, you may need to double the size of your solar panel system.
I know you can install a solar system and use a solar installer to add more panels as your energy needs change. However, I believe the best way to go about it is to size your solar system based on your expected future purchases, like a central air system, refrigerator, or heated swimming pool.
Check out some estimates in the table below
| Product | Average annual electricity you need (kWh) | Number of solar panels |
| Window air conditioning | 215 | 1 |
| Refrigerator | 600 | 2 |
| Electric vehicle | 3,000 | 9 |
| Central air conditioning | 215 | 1 |
| Heated swimming pool | 2,500 | 8 |
| Hot tub | 3,300 | 10 |
Planning in advance during installation will help you factor in some of these products and their energy consumption.
Will I Receive Electricity Bills With Solar Panels?
The utility company will send you a monthly electricity bill if your home is still connected to the grid. However, you will notice that the bill is low or zero if you haven’t used grid power. You may even receive a negative bill if you supply power to the grid through net metering.
But if you live off the grid and have installed solar panels at your home, you will not receive electricity bills.
What to read next:
- What Is The Average Electric Bill With Solar Panels?
- 6 Best Batteries for Solar Power Storage (Including their pros and cons!)
- 7 Solar Panel Cleaning Equipment and How to Use Them!
- Best Direction For Solar Panels For Optimal Energy Production.
Final Thoughts
How many solar panels are enough to power your home? We have established that the average American home will need between 20 and 25 panels to satisfy its energy needs fully.
However, the number of panels may change if the household adds heavy products and appliances that consume more power. But you get a rough idea of how you can calculate the number of panels your home requires.