Solar Panel Calculator: How Many Do I Need?

Written by: Meghan Harmon
Date: 7/1/2020

Tags: solar panel calculator, solar lease calculator, solar panel cost, solar price, panel cost, solar quote, PV system cost

The most common question from solar shoppers is how many panels they need for their roof. To calculate how many panels you will need to effectively power your home, your annual utility data will need to be analyzed by a sales consultant. Your system size will be designed to offset your annual utility consumption in kilowatts.

Pull Annual Energy Usage

A sales professional will need 12-months of utility usage to produce your solar quote. Solar billing is on an annual cycle because consumption fluctuates throughout the year. For example, you may spend a maximum of $500 in the peak of summer, because air conditioning use is much higher than in February.

If we built your system to account for a $500 average bill per month, your system would be too large and you would overspend on the cost of installation. On the other hand, if we looked at an “average” bill of medium usage in Feb-March, your solar production would come up a bit short and you would receive a balance due on your TrueUp bill. 

Plan for Increases in Energy Consumption

The purpose of your solar system is to generate enough electricity on an annual basis to cover your utility costs prior to going solar. 

It is important to let your sales consultant know if you plan on using more power after you go solar: 

1. Adjusting your thermostat to a lower temperature
2. Adding a pool
3. Buying an electric vehicle
4. Increasing # people living in the home
5. Home expansions
6. Purchasing large appliances

Significantly increasing your energy usage can lead to an owed balance on what is called a solar TrueUp bill. A True-Up is paid once per year, it summarizes your annual net energy costs or credits. It details both your solar production and energy consumption for the entire 12-month cycle. 

Account for Potential Installation Issues

Even though there are a lot of factors that come into play when sizing your solar system, the process is fairly simple. You need enough energy production to power your home effectively. However, there are a few things than can affect the pricing of your solar quote outside labor and materials. Make sure that your home is solar-ready by reading about these few things that can affect your home’s ability to have solar installed. 

Things that can impact solar quote pricing:

• If your roof does not have adequate space
• If you have trees or structures obstructing your available roof space
• If your roof isn’t in a condition to accommodate solar panels

If you run into one of these issues, you can likely still move forward with installing your new PV system. These factors will not change the number of panels you will need but can have an impact on your total project cost. Alternative solutions may include tree removal, roof repair or re-roofing work, and exploring options for ground mounts or solar structures. 

Now that we’ve covered everything that goes into producing your solar quote, it is time to do some math. Use the chart below to approximate what size system and how many panels you will need to power your home.