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Calculating Solar Panel Output - a Complete Guide

Calculating Solar Panel Output

Most of the world’s population is trying to reduce their carbon emissions and pollution by turning to power-generating processes that use renewable energy.

With the advancement in technology and the rise in global warming, people are making the switch to a solar power system and living greener by powering their homes with solar energy. 

Installing solar panels on your home comes with so many amazing benefits, from eliminating your energy bills to helping the environment through the use of renewable energy. But, before going green and purchasing a solar panel, it is important to know how to calculate solar panel output and efficiency.

The following guide will show you how to easily calculate solar panel output and efficiency, as well as what things to consider before you decide on the placement and installation of your very own solar panel.

Orientation, Placement, and Efficiency

There are a few important things that you would need to consider before you can install and calculate your solar panel's output.

solar panels efficiency calculation

Things like your solar panel’s efficiency, the location your solar panel is placed, and the direction your solar panel is facing, all influence the solar panel’s output.

Orientation and Placement

Your location is an important factor for your solar panel output voltage. You want your home to be in direct sunlight for most of the day. Generally, you want between 3-6 hours of direct sunlight each day, depending on the weather conditions.

It’s important to make sure there are no huge overlying shading trees or any other obstructions that are blocking the sun rays from making direct contact with your solar panel.

The more access the solar panels have to direct sunlight throughout the day, the larger the final solar output they produce.

Make sure that your solar panels are placed on a roof or location that is always facing south in the northern hemisphere and north in the southern hemisphere. 

This is the best orientation if you want to make your solar panels more efficient as they receive direct sunlight for long hours of the day. However, west-facing solar panels can also produce a significant amount of energy.

To get the best energy output of your solar panel, make sure that you do some visual research and monitoring before deciding on the placement and orientation of your solar panel.

Solar Panel Efficiency

Solar panel efficiency is an important factor in determining the final output of a particular panel. The ability of a panel to convert the sun’s rays into usable energy is known as the solar panel’s efficiency.

In simpler terms, the efficiency of solar panels tells us how effective the panel is at converting solar energy into household electricity.

If a solar panel has an efficiency of 30%, it means that 30% of all incoming sunlight that makes direct contact with the solar panel will be converted into electricity. The higher the solar panel's efficiency percentage, the greater the overall energy production.

Solar panel efficiency is also impacted by other factors which can either be beneficial or detrimental for the energy output. The reflectivity of individual solar cells, shading from tree overgrowth, long periods of cloud coverage, air pollution, and thick snowy conditions all impact the panel efficiency. These same conditions also shorten the solar panel's lifespan further reducing solar panel efficiency over time.

How to Calculate Solar Panel Output

Now that you know a little bit about solar panels, it’s time to get a little bit comfortable with calculating their energy output.

The good news is you don’t need to be a rocket scientist or a mathematician to calculate the energy output of a solar panel.

Many websites and manufacturers make it seem complicated to calculate solar output, but this isn’t the case. In fact, calculating solar output is simple and a painless process.

Calculating solar output is dependent on the solar panel’s watts and the average hours of sunlight per day, but we also must consider the other variables of orientation, placement, and solar panel efficiency. 

Generally, to account for these variables we need to multiply the final sum by 75% or 0.75 to give us the final energy output of the solar panel.

For instance, if you purchase a 300-watt solar panel and you live in an area that gets around 6 hours of sunlight during a cloudless summer’s day.

calculate solar panel output

You would simply take the 300 watts and multiply it by the 6 hours of sunlight which would equal 1,800. Remember that you would need to multiply this number by 75% to take into account the variables mentioned above. This will give you your daily watt-hours and, in this case, you would have 1,350 daily watt-hours.

To convert this number into the more familiar numbers represented on your electricity bill, divide your daily watt-hours, 1,350, by 1,000. This will give a final output of 1,350, which is known as the solar panel’s kilowatt-hours per day.

You might find that your final answer will have a few decimal places. If this is the case, simply round up your final output to make it easier to read.


Solar panels are excellent clean energy-producing alternatives and a great option to do your part in protecting the environment by reducing your carbon footprint.

Calculating solar output doesn’t involve overcomplicated mathematic formulas and you don’t have to be rocket science to calculate it. In fact, we just showed how simple and quick the process is, but even if you need the extra help, most solar panel companies will always assist you in these calculations just in case.

Remember to always consider the variables that influence the final solar output before deciding on the final placement for your solar panel installation.

Now that you’re pretty much an expert in all things solar, it’s time to make the switch to renewable solar energy and to get to calculating solar output like a professional.

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