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Solar Panel Calculation: The Ultimate Guide

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Importance and Application of Solar Panels

Solar panels are widely put to use in a variety of settings to provide the power needed to operate in our modern world. When we are so reliant on technology, we need the power to keep up with everyday demands. Solar panels help us ensure that there is the power necessary for everything to keep running.

Significance of Solar Panel Calculation

Everyone can benefit from having a system of solar panels in their home or ready to go with them on a long journey to a new destination. From powering your home to spending a night out in the woods camping, solar panels are the best tool to keep everything charged for the moments that you really need it.

One of the biggest factors of buying a system of solar panels is following the right solar panel calculations. Calculating the right number of solar panels that you need for any use is a complicated process that can be challenging for those who are just learning all about solar energy. In this article we will go over everything from the basics to how calculate the right number of panels for your needs.

solar panel calculation - Growatt

Understanding Basic Concepts of Solar Panels

Before diving in too deep, it’s an important step to understand the basics of solar panels. They are a highly advanced piece of technology that everyone can easily get their hands on. This is just a quick explanation of how technology has evolved to capture the sun.

How Solar Panels Work: Basics of Photovoltaic Conversion

Photovoltaic conversion. The term itself is a lot to take in and understand, but it can be done easily if you simply look at the words and break it down. Photo comes from Greek origins meaning light. Voltaic stems from the man who perfected the chemical process to create energy. Together, photovoltaic just refers to light energy.

Solar panels convert light into energy that we can use for everyday needs like charging your phone or running every little gadget you have, like a toaster oven. All of that energy can come directly from the light headed in our direction from the sun.

Grasping Solar Radiation and Irradiance Concepts

To understand solar panels, you must understand solar radiation and irradiance. Solar radiation is the term for the light waves coming from the sun and irradiance simply refers to the power per unit area of electromagnetic radiation making contact with a surface. In other terms, it’s how much power you get from the sun hitting the solar panel. This is often measured in watts per square meter.

Solar Panel Output Calculations

Figuring out the solar panel output is the main piece of doing your solar panel calculation. This will be what you use to understand how much power you can get from a panel, which will help you decide which panels to buy and how many.

Distinguishing Nominal Power vs. Actual Output

Nominal power refers to the nameplate capacity, or intended load, of a photovoltaic device, more commonly referred to as a solar panel. This just states how much power the solar panel is designed to be capable of putting out for a sustained period of time.

The actual output, the watts at any given moment, will fluctuate much more. The actual output will depend highly on the angle and strength of the sun, the time of day, the temperature, and so much more.

Estimating Expected Output per Solar Panel

Estimating the expected output for each solar panel is a relatively easy calculation.

The daily watt hours for a solar panel is equal to the average hours of sunlight per day multiplied by the solar panel watts, multiplied by the efficiency of the solar panel.

Under ideal conditions, the calculation is simple. You will take the wattage of the solar panels and multiply that by the number of hours you have sunlight.

So, at 200W, Growatt’s solar panels will have an expected output of 200Wh in one hour.

However, this does tend to rely on other factors that can affect the calculation of actual solar panel output.

solar panel calculation - Growatt

Factors Affecting Your Calculation of Actual Solar Panel Output

There’s a lot that goes into making sure your calculations are accurate for your solar panel output. Everything in the environment can be a factor just as easily as the quality of the panels that you buy.

Direction and Location

The direction and location of your solar panels will be one of the single greatest factors for determining how much power you can get out of a panel.

Maximizing this is easy. Start by gathering and analyzing sunlight data by using solar maps and online tools to find out where to place your panels and at what angle. Panels that are pointed directly at the sun during peak hours, but still can capture light throughout the day, will be much more efficient than those at an odd angle.

Solar Panel Efficiency

Unfortunately, not all the energy that comes from the sun is being converted into energy with your solar panels. A lot of that energy is lost to reflection, heat absorption, and more. Because of this, you need to factor in the conversion efficiency of the panels that you are using in order to get an accurate calculation.

Growatt’s panels boast a high rate of 22%, meaning just over a fifth of the sun’s energy coming in will be effectively converted into power.

Surrounding Environment

Everything around the panels will have an influence on how much sunlight they are capturing. If there are trees around that provide too much shade, the panels won’t catch light for a significant chunk of the day. These same trees may produce pollen that covers and occludes the panels, reducing their overall output.

Take into consideration anything that may come in between the sun and the panels. Dust, shadows, and other environmental factors can have a huge influence on the power that you are getting from your panels.

Calculating Solar Energy Demand

Once you’ve figured out how much power a single panel can get, you need to know how many panels you need. This all comes down to determining your solar energy demand based on your past energy consumption.

Understanding Your Energy Consumption Patterns

The best way to figure out how much energy you consume is to look at the patterns throughout the year. Different times of the year will require more energy than others. In the winter, you need more power to heat the house, while in the summer you need less lighting and can simply open the windows to cool down.

Past electricity bills are the best way to understand these patterns. Dig up as many old bills as you can and look at how much energy you paid for each month. These trends will show you how much power you need to produce and store over time.

Computing Daily, Monthly, and Yearly Energy Needs

With all of these numbers and trends, you can figure out how many panels you need for daily, monthly, and yearly usage. If you need a higher amount of energy at certain times, you may look into a power station that can hold the excess energy produced throughout the day.

These power stations like the INFINITY 1300 are the best way to produce and store energy so you can continue to rely on the energy collected from the solar panels once the sun is down.

Pairing a portable power station and a quality set of solar panels will leave you with a top-notch solar generator designed to utilize solar power and store it for later use.

solar panel calculator - Growatt


Calculating your solar panel output and energy demands is one of the most important steps of the process of switching over to solar energy. Doing this helps you understand how much power you are using, but can also show you how much money you can save by switching over to solar.

Conduct detailed calculations and do a hefty amount of research when considering making an investment in solar energy. This is a cost that will save you money over time, but how much money and how soon will be determined by how well you do the solar panel calculations.

Don’t be overwhelmed by the math and science involved in solar panel calculations. The process is simple and you can easily find tools online to help you through the entire process, or you can always contact a professional for an extra hand. Making the switch to solar is worth both the time and financial investments that are required.


What solar panel size should I choose?

The right size solar panel depends on how much energy you are hoping to produce and how much space you have to set up your solar panel. Determine your energy needs and then you can make an informed decision on solar panel size.

How many solar panels do I need?

The number of solar panels is directly determined by the output of the panels you are buying and your energy demands. Simply divide the energy that you want each day by the capacity of your solar panels and you will find a simple number for your system.

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