How Many Solar Panels Do I Need

February 1, 2024

There was a notable increase in solar power globally in 2022, totaling 239 gigawatts (GW). That’s a big deal because it finally surpassed the terawatt (TW) scale. This marks a huge 45% increase compared to the previous year, showing that solar energy is growing fast globally.

This significant growth confirms that solar energy isn’t just a trend—it’s here to stay and grow.

house with solar panels for home on the roof

Source: regenpower

Solar installations are happening all around the world, highlighting how important solar energy is in meeting our increasing energy needs. Picking the right number of solar system panels is a big deal because it affects how much energy your home can produce and how much money you can save in the long run. The data tells us that installing too few panels might leave your home with not enough power, while installing too many could cost you more than necessary.

In this article, we’re going to help you figure out how to calculate solar system sizes that are just right for you. We’ll break down the important things that affect the number of solar panels for houses you need so you can make smart decisions about your energy future. We’ll talk about the different types of residential solar panels, how the weather can play a role, and even how to calculate energy efficiency. Our goal is to make the whole process of going solar easy to understand and not confusing.

Popular Myths About Solar Panels Busted 5

Understanding Your Energy Needs

When switching to solar power, you need to know how much energy you need to meet your energy needs. Understanding this will help customize the solar solution to fit your needs perfectly.

view of residential solar panels on the roof house

Source: vecteezy

How To Calculate Solar System Size

In 2022, the average home power usage in the United States, according to the U.S. Energy Information Administration (EIA), was around 899 kWh per month. Knowing this average makes estimating your energy requirements easier.

What is your household’s monthly electricity consumption? To ascertain this, you must examine your utility bills and take note of any variations in consumption. Do you use more energy during some months than others? This could result from using seasonal equipment like air conditioners or space heaters or from having more demands for heating or cooling.

Your energy habits will be thoroughly explained by the responses to these questions. You could consume more energy in the winter if you live in a colder region, for instance. Thus, it would be necessary to think of a solar system that can manage these peak times. Conversely, if you reside in a warmer region, you may have more energy requirements during the summer, when air conditioner usage peaks.

It takes more than just math to analyze your energy use habits. You may plan your solar system to satisfy this continuous demand if your annual power use is relatively constant. However, your solar system should be powerful enough to manage these surges if there are obvious peaks throughout certain seasons.

Elevate Your Energy Awareness

Use monitors to have a better understanding of your energy requirements. It is simple to use these monitors. All devices that run on 120 volts may have their power use measured by them. However, major equipment that needs 220 volts cannot be utilized with them. Most hardware shops sell energy consumption meters. They are in the $25–$50 range.

electricity usage monitors which help calculate solar system size

Source: youtube

Web-based resources are also accessible. One such program is Home Energy Saver, which is run by the US Department of Energy. These provide you with customized insights into the trends of your energy use. You may get important information by using these resources. Your decision-making about the dimensions and power of your solar panels for houses will be aided by this.

Efficiency Residential Solar Panels

Effectiveness, or efficacy, is a critical factor in determining the amount of power generated by solar panels for houses. Electricity generation from solar radiation is directly proportional to the efficiency of the panels. This aspect holds significant importance, particularly when dealing with limited rooftop space and the need to obtain a sufficient amount of energy.

what you need should know about efficient solar panels for houses

Source: genusnigeria

How Efficient Are Different Types of Solar Panels for Houses

Monocrystalline panels, polycrystalline panels, and thin-film panels are the three primary types of residential solar panels.

  • Monocrystalline panels

Monocrystalline solar panels for houses are widely recognized for their high-efficiency levels, which generally span from 17% to 22%. They convert sunlight into electricity with greater efficiency due to the improved electron flow made possible by their single-crystal structure.

view of types of standard solar panels for houses

Source: newsouthernenergy

  • Polycrystalline panels

Polycrystalline residential solar panels have an average efficiency rating of 13% to 16%, which is marginally lower than that of monocrystalline panels. Conversely, they are more economical and provide a rational trade-off between functionality and cost-effectiveness.

  • Thin-film panels

Although less efficient than their crystalline counterparts, thin-film solar panels for houses are frequently more affordable and flexible. The typical range of their efficiency is from 10% to 12%. Large installations in which space is not an issue may find them to be appropriate.

Consider polycrystalline residential solar panels if you possess a substantial amount of roof space due to their cost-effectiveness. On the contrary, monocrystalline solar panels for houses may offer increased efficacy in situations where space is restricted, notwithstanding their potentially greater initial investment expense.

Achieving a solar installation that maximizes the sun’s energy output is possible through the judicious consideration of space availability, expense, and efficiency.

A Comparison of the Three Main Types of Residential Solar Panels

This table compares monocrystalline, polycrystalline, and thin film solar panels for houses and how the positive and negative aspects of each can influence your personal preference.

view of factors that affect residential solar panels' wattage

Source: unboundsolar

Space requirements, cost, aesthetics, and durability are among the many aspects considered in the comparison.

AspectsMonocrystalline solar panels for housesPolycrystalline solar panels for housesThin-film solar panels for houses
Cost$1 to $1.50 per watt$0.75 to $1 per watt$0.75 and $1.10 per watt
AppearanceUniform dark colorVaried color and appearanceDiverse colors and textures
DurabilityHigh durabilityModerate durabilityModerate to low durability
Installation FlexibilityLess flexibilityModerate flexibilityHighly flexible
Temperature PerformancePerforms well in high temperaturesModerate performance in high temperaturesSensitive to high temperatures
WarrantyLonger lifespan and warrantyModerate lifespan and warrantyShorter lifespan and warranty
Suitable ApplicationsResidential and commercial installations with limited spaceVersatile for various installationsLarge-scale installations with ample space
Popular Use CasesRooftop installationsResidential and commercial projectsLarge-scale solar farms
Environmental ImpactLower carbon footprintModerate environmental impactHigher carbon footprint
Overall ConsiderationHigh efficiency but higher costBalanced efficiency and costCost-effective but lower efficiency

Location and Climate Factors

Determining the optimal quantity of residential solar panels necessitates an investigation of specific geographical and climatic factors:

  • You must begin by determining the average amount of sunlight that falls on your region. Solar radiation data is made available by the National Renewable Energy Laboratory (NREL). The Southwest region of the United States, which includes Arizona and Nevada, receives significantly more solar radiation than the Pacific Northwest. The variation in sunlight levels directly affects how many residential solar panels you need for optimal energy production.

Using data from 1998 to 2016, the NREL generates a map depicting the annual average daily total solar resources. Territories that receive <4 kWH/m2 are marked in light yellow on the map, and with color saturation, the intensity increases for each 0.25 kWH/m2 to a max of 5.75 kWH/m2.

map provides annual average daily total solar resource using 1998-2016 data


  • Additionally, one should take into account weather patterns. Meteorological data indicates that regions characterized by dense cloud cover or inclement weather, such as the Pacific Northwest, experience reduced solar irradiance. This information can help calculate the required power for the residential solar panels.
  • The efficacy of solar panels for houses can also be affected by the shadows cast by trees and buildings. The potential impact of these shadows on your residential solar panels can be estimated using instruments such as the solar pathfinder. This analysis may yield significant knowledge regarding possible energy wastage. It can aid in determining the better placement of solar panels to optimize sunlight exposure.
view of residential solar panels under trees

Source: gridfree

  • Additionally, one should take into account extreme weather phenomena, including hurricanes. One might want to contemplate hurricane-resistant solar panel designs if they reside in a region prone to hurricanes, such as the Southeastern United States. These measures can effectively fortify the panels against the effects of high gusts.

The Southwest and other regions that receive abundant sunlight may require fewer residential solar panels. This is corroborated by solar insolation data from NREL. Conversely, regions such as the Pacific Northwest that experience less consistent sunlight may require a greater quantity of solar panels for houses to compensate for their diminished solar exposure.

System Orientation and Tilt Residential Solar Panels

Determining the optimal orientation and inclination for solar panels for houses in your region is crucial. This decision significantly affects the ability to produce energy with residential solar panels throughout the year:

  • In the United States, the ideal inclination aspect may differ. In the southwestern region, which is in closer proximity to the equator, an optimal inclination ranges from 15 to 20 degrees. A 40-degree inclination, however, might be more favorable in the Northeast, which is located further north. The United States encompasses a broad spectrum of latitudes, so the tilt must be adjusted according to the location of your solar system.
view of orientation standard residential solar panels on a south

Source: linkedin

  • Additionally critical is the orientation, or the direction in which residential solar panels face. Annually, solar panels for houses oriented south receive the greatest amount of solar energy. However, there are circumstances in which facing east or west with residential solar panels may be preferable. This is especially true if the morning or afternoon is when you expend the most energy.

How Batteries Impact the Number of Solar Panels

While solar panels for houses generate electricity during daylight hours, solar batteries facilitate the storage of excess energy for later use, such as at night or on overcast days.

The impact of a solar battery on the number of residential solar panels required is quite significant. With the help of solar batteries, you can store excess energy produced during periods of high solar generation. This can potentially reduce the necessary number of residential solar panels to meet your energy needs, especially during periods of insufficient solar activity.

The expanding prevalence of battery storage warrants some contemplation. The battery storage capacity in the United States had reached 1,650 MW by the conclusion of 2020. The National Energy Information Administration, however, projects that by 2024, the nation will possess approximately ten times that quantity.

view of standard residential solar panels with solar battery

Source: regenpower

Homes with intermittent access to sunlight or those aiming for off-grid living can greatly benefit from the installation of solar battery storage. By doing so, one can not only guarantee a dependable power provision but also reduce the necessity for an overly sizable installation of solar panels for houses.

Despite this, it is necessary to pay attention to the fact that the influence of solar batteries on the total number of residential solar panels depends on several factors to consider, such as local weather patterns, individual energy demands, and geographic location.

Energy Conversion and Loss

A specific quantity of energy is lost during the conversion of sunlight to electricity. This loss occurs also during the conversion process of direct current (DC) to alternating current (AC). As you know, residential electricity is supplied via in-form AC.

Solar panel efficiency typically ranges from 15% to 20%. As a consequence, a portion of the solar radiation that strikes the solar panels for houses remains unreformed into electrical energy. Additionally crucial to minimizing energy loss is the inverter’s efficacy that transforms DC to AC is an inverter.

Inverters may exhibit variations in efficacy. Typically, the efficiency of high-quality inverters exceeds 90% to 95%. In terms of efficiency, less expensive alternatives range from 75% to 85%, resulting in higher energy losses.

You should consider investing in high-efficiency residential solar panels and inverters to maximize the performance of your solar panel system. This approach can improve the overall performance of your solar energy system. Furthermore, this can potentially decrease the overall quantity of residential solar panels necessary to fulfill one’s energy needs.

Solar Panel Sizes Calculation

We’ve now reached the crucial step of determining the size of the solar panels for houses for your solar energy system. To better understand this calculation, let’s consider an example.

Imagine residing in an Arizona home. Your goal is to utilize solar energy to offset its average monthly electricity consumption of 889 kWh. Arizona receives approximately 5.75 kWh/m2 of daily sunlight, per NREL data.

  • We begin by converting monthly consumption to daily consumption. We do this by dividing 899 kWh by 30 days. So we get the result is 29.96 kWh per day.
  • Following this, taking into account solar insolation for every square meter of residential solar panels, we approximate the daily energy output. Let’s use the average efficiency of solar panels for houses for calculation, which is 18%.
  • Consequently, the daily energy output per square meter amounts to 1.04 kWh/m2. This is obtained by 18% multiplication of 5.75 kWh/m2.
  • To satisfy the daily energy requirement, an Arizona home demands 29.96 kWh, which is divided by the daily output per square meter. Thus, 28.80 m2 is obtained.

Therefore, in order to meet its average daily electricity demands, the dwelling in Arizona would require approximately 28.80 m2 of residential solar panels.

In light of the available roof space and panel type, the householder is now able to select the optimal option. If there’s not much space, might prefer monocrystalline panels. Although they operate at a slightly higher cost, they are more efficient.

Do not forget that this calculation is simplified. A solar expert should be consulted for a more precise evaluation. With your specific circumstances in mind, they can modify the calculation.


By understanding your energy needs, assessing solar panel efficiency, and considering location, climate, and other variables, you can decide how many solar panels you need. In the above example is clearly visible how crucial it is to integrate data. This facilitates an accurate estimation of the necessary solar panel dimensions. It is essential to consult with a solar expert. A more precise evaluation customized to your specific conditions can be obtained from them.

Varying initial expenditures may be required for residential solar panels. It is essential to strike a balance between efficient and cost-effective solar panels for houses. Assess the amount of available space on the roof. Select a solar panel variety that corresponds with your objectives. Solar energy systems represent an investment in your property. Furthermore, it is an environmentally sustainable option. Optimal energy production is guaranteed by the optimal quantity of solar modules. Moreover, it results in sustained financial savings.

Andy Worford
Andy Worford

Andy is a Founder, Chief Content Officer, regular contributor, and idea generator behind Solar Power Systems. He is well-versed in various aspects of solar energy, including photovoltaic systems, solar policy trends, and green technology innovations.