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  • Writer's pictureHaleigh Shutt

"Sizing Up Solar: How to Calculate Your Perfect Solar Power System"

Calculate solar

Switching to solar power is a smart move for both the environment and your wallet. However, determining the right size for your solar power system can be a bit daunting. Getting the size right is crucial to ensure you generate enough electricity to meet your needs without overspending. This blog will guide you through the steps to calculate the perfect solar power system size for your home.


Understanding Your Energy Needs


The first step in sizing your solar power system is to understand your energy consumption. Here’s how you can do it:


1. Review Your Electricity Bills: Look at your electricity bills for the past year to get an idea of your average monthly and annual electricity usage. This is usually measured in kilowatt-hours (kWh).

2. Calculate Your Daily Usage: Divide your total annual usage by 365 to get your average daily energy consumption. For example, if you use 10,000 kWh annually, your daily usage would be approximately 27.4 kWh.


Determine Peak Sunlight Hours


Solar panels generate electricity based on the amount of sunlight they receive, which varies by location. The term "peak sunlight hours" refers to the average amount of time each day that the sun is strong enough to produce usable energy. You can find this information for your area through online resources or solar energy tools.


Sizing Your System


Now that you know your daily energy needs and peak sunlight hours, you can calculate the size of your solar power system using this formula:


System Size (kW) = Daily Energy Consumption (kWh) / Peak Sunlight Hours


For example, if your daily energy consumption is 27.4 kWh and your area receives 5 peak sunlight hours per day, your system size would be:


27.4 kWh / 5 hours = 5.48 kW


Considering System Efficiency and Losses


Solar panels don’t operate at 100% efficiency. Factors such as shading, inverter efficiency, and panel orientation can affect performance. It’s common to include a system loss factor, typically around 75-85%. Here’s how to adjust for efficiency:


Adjusted System Size (kW) = System Size (kW) / System Efficiency


Using the previous example, if we assume an 80% efficiency:


5.48 kW / 0.80 = 6.85 kW


Choosing the Right Number of Panels


Solar panels come in different wattages, typically ranging from 250W to 400W. To determine the number of panels you need, use this formula:


Number of Panels = System Size (kW) * 1000 / Panel Wattage


For a 6.85 kW system using 300W panels:


6.85 kW * 1000 / 300W = 22.83


You would need approximately 23 panels.


Roof Space Considerations


Ensure your roof has enough space to accommodate the number of panels you need. Standard solar panels are about 17.6 square feet each. Multiply the number of panels by the panel size to determine the total roof space required.


Total Roof Space (sq. ft.) = Number of Panels * Panel Size (sq. ft.)


For 23 panels:


23 * 17.6 sq. ft. = 404.8 sq. ft.




Calculating the size of your solar power system involves understanding your energy consumption, peak sunlight hours, system efficiency, and roof space. By following these steps, you can ensure your system is sized correctly to meet your energy needs efficiently.


Making the switch to solar is a significant investment, and getting the size right is crucial for maximizing your savings and environmental benefits. If you’re unsure about any part of the process, consider consulting with a professional solar installer who can provide a detailed analysis and tailored recommendations for your home.


Switch to solar and shine bright with energy independence!

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