Black and silver solar array in a field near a hill


A lot of businesses nowadays are taking advantage of the financial benefits of installing eco-friendly solar panels. With modest payback and an average ROI going above 10%, most businesses have either jumped the gun or are seriously considering solar power as it is an attractive financial investment. Some very generous tax perks are offered by both state and local governments that can convince even the most thrifty business owners to switch to solar.

Aside from the material benefits that going solar will give to your company, you will also have a better employee-employer relationship, stronger customer loyalty and attraction, increased goodwill in the community, and a competitive advantage. So, this commercial solar calculator will guide you to take your first step towards a greener future.

How Much Solar Power Do You Need?

To find your business’ average energy consumption, you need to look at your past electricity bills. By doing so, you can easily calculate how much power you need to produce as well as the number of solar panels by multiplying your establishment’s hourly energy consumption by the peak sunlight hours in your area. After doing that, you need to divide that by a solar panel’s wattage.

You also need to account for both low-wattage and high-wattage panels that produce 150W and 370W, respectively. The amount of sunlight that your establishment’s roof gets, the size of your battery storage, and your business’ roof size are factors that need to be considered as well.

If you follow this commercial solar calculator and work with Beach Cities Solar Consulting, all of these calculations will be done for you. But for you to have some rough idea of how many solar panels you will use for your business, the following are some of the common questions that professionals might ask:

1. How Many Watts Do You Consume?

You need to look at your utility bill to get your average usage. The keyword that you need to look for is “Kilowatt Hours (kWh) Used” or something along those lines, then take note of the period it accounts for. If your electricity bill doesn’t show how much energy you use, look for the first and final meter readings and subtract the previous reading from the current one.

The most important thing that you need to look for is the daily and hourly usage for this solar power calculator. So, if the daily average is not indicated, you need to divide the monthly or yearly average by either 30 or 365 days, respectively. After that, divide it by 24 to determine the hourly electricity usage. The result will be in kilowatt-hours (kWh).

On average, small businesses consume around 15,000 kWh to 25,000 kWh annually while medium-sized businesses consume between 30,000 kWh to 50,000 kWh. So, if your computation falls somewhere between these numbers, that’s the number of kilowatt-hours you need your solar power system to produce if you want to provide 100% green energy for your business.

However, you need to take into account that you need to have a “cushion” of at least 25% to account for slight dips in solar panel efficiency. External factors like rain, snow, leaves, dust, and other debris will affect the efficiency of your solar panels. A cushion will ensure that you will hit your daily target and your business can generate enough energy throughout the day. This will make your solar panel cost calculator more accurate.

2. How Many Hours of Sunlight Does Your Area Get?

Your business’ location can be a make or break factor if you want to install a solar power system. Since the peak sunlight hours in your area will affect the amount of power that solar panels produce, this is a factor that should be considered. So, if your business is located in Houston, it will produce more energy than if it is in Seattle since the former has a greater number of peak sunlight hours than the latter.

Black and silver solar array on a snowy field


But this doesn’t mean that you shouldn’t install a solar power system if you live in an area that receives less sunlight, you’ll just need to install more solar panels. Also, a 10kW solar system calculator would result in cheaper upfront costs if your area receives more than enough sunlight.

How To Calculate Solar Power Return on Investment (ROI)

To see if your investment will make sense, you simply need to subtract the annual electricity savings from the upfront cost of the system, net of rebates and tax credits, until it results in a positive number. So, if you have a $300,000 solar power system (with a 30% or $90,000 less due to federal tax credit and $90,000 in savings made from depreciation tax) that results in an annual energy savings of around $20,000, your investment will pay back after 6 years.

To make this step easier, you can create a solar power return on investment calculator Excel spreadsheet or use this solar calculator if your business is in California.


Knowing some of the facts and numbers presented in this guide will give you a better idea of the optimal number of solar panels for your business’ energy needs. Pick a professional solar installer to help assess if your estimates are accurate. Consider things like your commercial building’s roof architecture, angle to the sun, and other external factors that can affect a solar power system’s energy efficiency and output. They will also help you in physically arranging the correct number of solar panels in your roof so you could hit your daily energy production targets.

Aside from that, you should also consider net metering to maximize your ROI. By being part of this program, your utility company will give you credit for adding your excess solar energy production to the grid. But if you don’t have an energy storage system, you can use those credits to pay for the power that you draw from the grid at night.

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