How many solar panels do I need?

Recently, solar panels have become extremely popular among people mainly because they are environment-friendly as well as their desire to reduce their electricity bills as much as possible. If you are someone who wants to install solar panels in their house or any other property then in the very first step you need to ask yourself how many solar watts do I need.

Although I want to help you out as quickly as possible I cannot just give you a one-word answer to the question how many solar watts do I need? because it will ultimately lead you to nowhere. 

In my case, before I start contacting any dealer for purchasing and installing solar panels as a responsible buyer I would have to consider some essential factors and some calculation which is going to help everyone in the long run. If you are thinking about the same then you don’t need to worry about anything because I am here to help you out. You can quickly jump to the calculator here.

Determining factors for the size and the number of your solar panels

Multiple factors determine the actual size and the number of solar panels you should install in your home. If you do not consider all these factors it is highly likely that your money will go to waste. Read on to know more about these factors so that you can successfully calculate the solar panel requirements of your home.

Your monthly or yearly electricity usage

To arrive at the conclusion of your question, how many solar watts do I need? First, you will have to calculate your home’s monthly and yearly electricity usage. The total amount of energy consumed every year is one of the fundamental factors which will make you understand how to calculate solar panels.

According to the United States Energy Information Administration or EIA, an average household’s yearly energy consumption limit is around 11,000 kWh. You also need to note that all the appliances (no matter how big or small) are taken into account while calculating your household’s total energy consumption.

The wattage of the solar panel

Solar panels can be separated based on solar watts per square foot and that is why you have to have an idea about your household’s daily energy consumption to know which solar panel would be suitable for your household.

This factor will decide what is the most suitable solar panel power output per square foot for your home. Currently, you will find solar panels whose output ranges from 250 to 400 watts per square foot. Therefore, if you are thinking about installing solar panels then you will have to choose between this particular range.

The ratio of energy production

The ratio of energy production is another important factor you need to consider while determining the size and the total number of solar panels you will need at your home. Usually, you may think that solar panels produce the same amount of energy as the actual size of the system (which indicates a 1:1 ratio).

In reality, it depends on the amount of sunlight the installed solar panels will be receiving at your home. For example, if you are currently staying in a place like Hawaii where there is ample availability of sunlight then (supposedly) your 10kW system can generate around 16kWh electricity annually which makes the production ratio 1:6. However, if you are currently staying in a remote place with lower sunlight level you may not receive the same output as you are receiving in a place like Hawaii. 

Therefore, if you want to generate enough electricity that will support the energy consumption of your household in a place like where the sunlight is comparatively low then you will have to increase the number of solar panels you are willing to install.

Calculating how many watts of solar panel I need

While you are checking out how many solar watts do I need? You can also calculate the number of solar panels you will require to harness the sunlight and use it to your advantage. Below I have mentioned a systematic process with the help of which you will be able to know how to calculate solar power needs for your home and implement the same during the installation process.

Know how much electricity you need

How do you know that you are installing an adequate solar system that will power up all the appliances in your household? To get your answer you will have to look at the monthly electricity bill and find out the exact amount of power your household appliances are consuming on a monthly and yearly basis.

Mostly in the utility bills kWh or kilowatt-hours is the unit through which your electricity consumption is shown. The amount of annual energy consumption mentioned in the bill will be the answer to your question regarding energy consumption.

You also need to keep in mind that your electricity consumption will fluctuate drastically depending on your locality and seasons. For example, if you are living in Houston and have an air conditioning system (or HVAC) at your home your energy consumption will be huge during summer (because summer in Houston is extremely hot and humid).

Track down the amount of energy solar panels could produce in your region 

If you already know about the exact amount of annual power consumption in your household, your next step would be to check how much sunlight your locality is receiving. The amount of sunlight in your area can be measured by something called ‘peak sun hours’. It is an indicator of the intensity of the sunlight in your region. 

You can get the average of daily or even monthly ‘peak sun hours’ on the internet. For example, in the United States the average ‘peak sun hours’ differs between 120 to 150 hours. With this important information, you will be able to know how much kWh of electricity you can generate every month.

Find out the appropriate solar system size for your home

Now that you already know about your region, topography, monthly electricity needs, etc. it is time for you to focus on the next step which is to find out the exact size of the solar system that your home needs to satisfy its electricity needs. 

In this scenario, I can help you out by providing you with a calculation method through which you can calculate the exact size of the solar system you need to install. I will further explain the entire formula with an example to simplify the entire process.

The formula is:

kWh per month / (avg sunlight per day * 30) = kW solar system

Here is how you can use this formula. Suppose, you are receiving sunlight for 6 hours and your electricity consumption is 900kWh per month. According to the above-mentioned formula, the solar system you will require is 900/6*30 = 5kW. 

You should also remember that while searching for a solar system you will come across something like a 4kw solar system. This number signifies that the specified system will be able to produce 4*6 = 24 kWh of electricity per day (in a region that receives 6 hours of sunlight).

Now that you have understood how to calculate the exact amount of solar system you will require you won’t face any issues while installing a solar system for your household. Or you can use our calculator here:

Deduce the number of solar panels you will need

Now that I have already told you how to calculate solar power needs, you can easily figure out how many watts of solar panels I need. All you have to do is to convert the size of your solar system from kWh or kilo-Watt-hour to watts which can be done by multiplying the number by 1000. 

For example, 5kW * 1000 = 5000 watts. Now you can take this number (5000 watts in this case) and split it by the wattage number of the individual solar panels. If you want to use a 250 watts solar panel then to make an entire solar system for generating enough electricity for your house you will have to purchase 5000/250 = 20 solar panels.

In countries like the United States, on average, people need 340 square feet of roof space to install an effective solar system that can generate enough energy. However, if you do not have that much space on your roof then you can use better or more powerful solar panels with higher outputs. In this case, you won’t have to install fewer solar panels to satisfy your energy requirements.

Final words

By now you must have realized why I have not provided any one-word answer to your question: how many solar watts do I need? And instead offered you a broader outlook with which you will be able to tackle a lot of your problems related to solar panel installation. 

Therefore, before you install a solar panel system at your home, take into consideration each and everything related to the system so that you can generate enough energy to support your household electricity and prevent you from spending extra money on utility bills.

Frequently Asked Questions

How many solar panels does it take to power a typical household?

On average, a household requires about 17 to 21 solar panels to generate enough energy to perfectly run the household. However, the number of solar panels can differ according to your overall energy consumption, the topography of your neighborhood, etc.

Is 1 kW enough to run a house?

If your house has one refrigerator, a single laptop usage, a TV, three fans, and four lights then 1kW will be enough to support your household’s energy consumption. However, you also need to note that your house has to be a 2BHK or a 3 BHK house with a regular power consumption of 800 W.

How many solar panels do I need for 5KW?

If you want to install a 5kW solar system to cater to your household’s electricity needs then you need to install at least 15 to 20 solar panels that can produce enough solar panel output per square foot. You also need to note that you will require 25 to 35 m2 of roof space to install 15 to 20 solar panels.

How much AC can run in 1 kW?

If the solar panels you have installed receive sunlight from 9 am to 5 pm then they will be able to generate around 5 units of electricity every day. If you have a 2BHK home with a 1.5-ton inverter AC then a 1kW system can produce enough energy to support the same.

Can I run AC directly from a solar panel?

Yes, you can run AC directly through solar panels. No matter what kind of solar panel system you have installed (on-grid or off-grid) at your home you will be able to power your AC through the same and shrink down your electricity consumption.

In this article, we have covered different aspects of installing a solar panel and how people can calculate the number of solar panels they require before installing a solar panel. We have also covered different factors they need to keep in mind such as roof space, topographical locations, etc.

Meet the Authors

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Dax Linwood is a knowledgeable and experienced writer in the field of renewable energy, with a core expertise in solar energy. With a passion for sustainability and a commitment to advancing the adoption of clean energy, Dax's writing is both informative and engaging. He has worked on numerous solar energy projects, including solar panel installation and maintenance, and has a deep understanding of the technology and its benefits. Dax's expertise and dedication to the renewable energy industry make him a valuable resource for those looking to learn more about solar energy and its impact on the environment.

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