A Step-by-Step Guide on How to Calculate Solar System Size

In the first three months of 2023, the solar business in the US put in 6.1 gigawatts of solar capacity. That’s enough energy for more than 4 million houses. That number is poised to increase even more as utility companies across the country adopt new policies to increase their solar capacity.

Interested in solar power yourself but don’t know where to start? There are a lot of variables to consider when going solar.

The most basic is solar system sizing. Here’s everything you need to know about how to calculate solar system size. Read on!

Determine Your Energy Consumption

The first step in calculating solar systems is to determine the level of energy consumption you need. An estimate of total electricity consumption would give solar companies an idea of sizing a solar system.

Your electric bill is a great place to check this out. Look at the average kWh you use in a month or a year.

Take note of which months you use the highest kWh and how much electricity you consume during those months. Another way to determine your electricity usage is by multiplying the wattage rating of each appliance by its average running hours.

Assess Solar Irradiance

Solar irradiance is the amount of sunlight energy received per unit area. This is important because it shows how much sunlight is available for capture by solar cells in the system.

Solar irradiance data is often available from sources like the National Renewable Energy Laboratory (NREL) or local weather stations. A common method of accessing irradiance is through measurements taken with a solar pyranometer, a device that can detect the total amount of solar energy available for capture.

In this step, it is important to take note of your average daily peak sun hours. This is how many hours per day your location receives the maximum amount of energy from the sun.

Calculate Daily Energy Production

With info on solar irradiance in hand, the next step is to figure out how well your chosen solar panels work. The amount of sunlight that is turned into usable power by solar panels is usually between 15% and 20%. By multiplying the average daily solar irradiance by this efficiency, you can get an idea of how much energy a square meter of solar cells can make in a day.

Determine System Size

Now equipped with daily energy production per square meter, the next calculation ties back to your energy consumption. By dividing your average daily energy consumption (in kWh) by the daily energy production per square meter of solar panels, you arrive at the total square meters of solar panels required to satiate your energy needs.

Consider System Losses

System losses can include loss of power due to shading, dirt or snow accumulation on the panels, mismatches between the solar cells, and wiring inefficiencies. You should look at how the solar modules will be situated and calculate if there will be any shading or obstruction of the sunlight.

To counter these factors, introducing a derating factor is prudent. This multiplier, often ranging from 1.1 to 1.2, takes into account the anticipated energy loss, ensuring that your solar panel system compensates for these potential setbacks.

Select Panel Wattage

Panel wattage is the amount of electricity a solar panel can produce, which is measured in watts. It shows how much energy the panel can make when it’s getting the most sunlight. Higher panel wattage means that the panel can produce more energy, which affects the size and efficiency of a solar panel setup.

Since there are many different panel wattages on the market for solar energy, your choice will depend on how well your estimated system size fits with the options. Choosing solar panels with wattages that are close to what you need makes it easier to put them into your system.

Calculate the Number of Panels

After deciding on the power of the panels, the next question is, “How many solar panels do I need?” To do this calculation, divide the total size of your system (in watts) by the power of the chosen solar panels. The results give you a rough idea of how many panels you’ll need to meet your energy needs.

Consider Panel Orientation and Tilt

It’s important to take into account the orientation and tilt of the solar panels, as they can impact the overall efficiency of your system. Optimal positioning dictates that solar panels should face south (in the northern hemisphere) and be inclined at an angle equivalent to your geographical latitude.

Solar panel experts, like Blue Raven Solar, can help with the proper arrangement to ensure maximum exposure to sunlight and, consequently, optimal energy generation. Additionally, ensure that no obstructions are blocking your panels from receiving the most amount of sunlight.

Calculate the Space Needed for the Solar System

Start by measuring the total area of the solar panel installation surface. This will be the foundation for your calculations. Measure the area of the space needed for wiring, mounting hardware, and conduit.

Also, consider the available areas for storage of solar modules and batteries. Next, calculate the area of the modules and batteries that will fit based on their specific sizes.

Check the Total Solar System Capacity of Your Property

Ensure you have enough available roof and ground space to accommodate the calculated number of panels. Subtract the total space needed by the panels from the available surface. Once you have these calculations completed, you can begin estimating the total capacity of the solar system. 

Calculate Solar System Size Correctly for a Reliable Solar System

Calculating solar system size can seem complicated, but it is possible! An effective and reliable solar power supply relies on the correct calculations. Taking the time to do the math properly and understanding the process is essential to a successful outcome. 

With this comprehensive guide on going solar, you should now know how to calculate solar system size confidently! Go ahead and start calculating now!

For more great guides like this, check out the rest of our blog. There are many informative and exciting articles to find!

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