Commercial Solar System

How to Size a Commercial Solar System

How do you design a solar system and stick to a budget? How many panels do you need for peak performance? Here's to answer your questions.

Solar has become more efficient and affordable, which should interest any savvy business owner looking to cut down on energy costs. But how do you design a solar system and stick to a budget? How many panels do you need for peak performance?

Bell Solar & Electrical Systems is here to answer all of your burning questions.

What Sizes Are Available For Commercial Solar Systems?

Every solar panel’s size depends on the number of photovoltaic or PV solar cells. Since commercial panels have more PV cells than residential ones, they are more powerful and bigger.

Keep in mind, though, your business’s power consumption requirements, available roof space, and budget are what will determine how many solar panels you need and the overall size of the system.

How Big Are Commercial Solar Panels?

Typically, every PV solar cell measures six inches by six inches. Commercial solar panels have anywhere from 72 to 98 or more PV solar cells. This means, on average, they’re about 6½ feet long, 3 feet wide, and weigh around 50 pounds.

In comparison, residential solar panels only have 60 PV cells, so they’re usually about a foot smaller and weigh 42 pounds or so.

While commercial panels are designed to meet the energy demands of any business, you’ll still need to figure out the requisite commercial solar panel size that will meet your energy demands and fit your space. For instance, there are high-efficiency panels that are smaller and make the most out of an available space — and then there are larger ones that are less efficient but more affordable.

Keep reading to learn more about how to size a commercial solar system for your business.

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Factors to Take Into Account Before Sizing

Before you size your commercial solar power system, crunch some numbers to determine a budget and assess your available space. Also, are you looking into solar incentives or tax investment credits? Fo you have an unusual shape to your roof and are wondering if a ground array might work better?

Next, you’ll want to consider the following as well:

  • Average daily, monthly, and yearly sunlight exposure
  • Local climate and cloud coverage
  • The “orientation array” or tilt of the tiles toward the sun (usually south-facing is best)
  • Efficiency and reliability of different manufacturing brands
  • The timeline of a panel’s warranty, re: the natural degradation of the PV cells
  • Any future energy needs or expansion calculations

This list isn’t meant to be daunting, but rather gives you a solid foundation for success when you make the switch to commercial solar energy. However, if you have questions or concerns, contact Bell Solar & Electrical Systems today.

5 Steps to Size a Commercial Solar System

Each of these five steps will help you properly size a commercial solar system for your business and avoid oversizing or overbuying. It takes into account your energy usage, peak sun hours for where you’re located, and then offers some final insights to refine your system.

Once your system is installed, you’ll see benefits for years to come, since now, more than ever, is the best time to invest in clean energy and switch to solar.

1) Figure out your yearly energy usage

On every electric bill, you will see a section with your kWh or kilowatt-hours. This is your energy usage and how your utility company determines what to charge you. It’s also how you’ll figure out your energy consumption averages.

Start by assessing an entire year. Notice when your usage dips and when it peaks.

2) Figure out your monthly and daily energy usage

To get a rough idea of your monthly average, add up each month’s kWh throughout a calendar year, and divide by 12. Then, take that number and divide by thirty for your daily average.

Keep in mind that your commercial power system will likely overproduce in the summer due to all those extra sunny days. Some utility companies buyback that wattage from you or apply it to your account as a credit — especially in Nevada.

Also, you can Google appliance energy consumption tables and calculators if you want to delve further into your energy usage.

3) Figure out your peak sunshine hours

Peak sun hours refers to the measured intensity of sunshine in a specific area for one hour, when its energy averages about 1000 watts per square meter.

Google “peak sun charts” and then look for your closest city to find the peak sunshine of your locale. For instance, Las Vegas, Nevada, is one of the sunniest places in the U.S. and its peak sun averages about 6.41 hours in total.

4) Calculate your commercial solar system size

Now that you have your energy usage numbers, along with your peak sunshine hours, you can plug those into a formula to figure out how to size a commercial solar system for your brick and mortar.

A quick note, you will need to know a solar panel’s efficiency to get the correct number. The number provided, 1.15, is simply an example.

(Daily kWh ÷ average peak sun # of hours) ✖ panel efficiency factor 

= DC (Direct Current) Solar System Size 


(30 kWh ÷ 6.41 hours) ✖ 1.15 efficiency factor = 5.38 kW

Convert the 5.38 kW to watts by multiplying it by 1,000. In our example, your business would need a 5380 watts-sized solar system. And if each panel is 350 watts, you’d need around 15 panels.

5) Final Tweaks

There are a few final tweaks to consider when you have to size a commercial solar system. First, the available space and whether your building’s roof is a viable option. If not, you can look into alternatives such as pole-mounted panels or ground arrays.

From there, you can figure out whether you should opt for smaller, more high-efficiency panels or go with a larger size. To help you with this, you can utilize the PV Watts Calculator by the National Renewable Energy Laboratory to simulate your solar output. (There are instructions on the website to help you plug in the correct numbers.)

Finally, you can start researching and comparing different manufacturers, equipment, and panels.

Toss Your Electric Bill And Get a Tax Break 

After you size a commercial solar system and know what panels you’d like to buy, it’s time for installation and a stellar return on investment. 

Nevada utility companies have some of the highest rates in the United States for “net metering,” i.e. buying back your solar panel energy output. Also, with generous tax breaks and subsidies, solar panels pay for themselves within four to five years. And currently, the federal tax investment credit is at 26%, but it is set to go down over the next two years.

Follow this link to learn more about solar power advantages for small businesses.

Tap Into Renewable Energy With a Commercial Solar System From Bell Solar & Electrical

Solar is an excellent, eco-friendly choice that pays dividends for business owners. From tax breaks, to eradicating your electric bill, to shrinking your carbon footprint — this is the time to invest in renewable energy.

But in order to fully capitalize on solar energy, you’ll need to figure out your energy consumption and account for peak sun hours in your locale. Also, investigate your available space and figure out a budget. Altogether, this will help you pick the right panels in terms of efficiency, reliability, and size. (You don’t want to overbuy.)

Commercial solar panels can meet the energy demands of your business and save you money. Contact Bell Solar & Electrical Systems today with your solar installation questions and receive a free quote.

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