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How Much Power Do Solar Panels Produce?

Learn how many solar panels and solar cells you need to sustainably meet your home’s energy needs.
Solar Panels
5 minutes
Written by:
Joey Cheek
Updated on:
November 11, 2022

Most household solar panels on the market currently produce between 250 and 400 watts per hour individually.

The capacity of domestic solar panel systems typically ranges from 1 kW to 4 kW.

A typical home with a 4 kW solar panel system may generate about 2,850 kWh of electricity per year (in ideal conditions).

The output of a solar panel is influenced by several elements, including its size, capacity, location, and weather.

How to Estimate the Amount of Solar Panel Energy

The quantity of DC (direct current) power each panel can generate under typical solar panel test conditions determines its rating. The power generated by a solar panel is measured in watts (W), which correspond to the solar panel's optimum sunshine and temperature conditions.

Volts and amps are multiplied to determine wattage, where volts denote the electrical force and amperes (amps) the total amount of energy utilized.

Most residential solar panels have power output ratings between 250 and 400 watts, with more outstanding power ratings typically preferred to lower power ratings. Typically, the cost of solar energy is expressed in dollars per watt ($/W). Yet the total cost of your solar system is significantly influenced by the wattage of the panels.

For instance, you can figure out your solar panel output in the following way if you live in a sunny place that receives 5 hours of direct sunlight every day: 5 hours multiplied by 290 watts (the power of a high-end solar panel) equals 1,450 watt-hours, or nearly 1.5 kilowatt-hours (kWh). Accordingly, the output of each solar panel in your array would result in approximately 500–550 kWh of electricity produced annually.

Or, you could use the Centre for Alternative Technology's calculator to estimate how much power your solar panel system can yield. You should also ask your solar installer how much a solar panel produces before any solar panel installation.

What elements influence the production of solar panels?

It's crucial to comprehend the two main parameters that affect a solar panel's power output before evaluating the quantity of energy it can generate: cell efficiency and solar panel size.

Solar Panel Capacity

The solar panel system is most capable of producing electricity under perfect circumstances (sometimes called "peak sun").

This is sometimes referred to as "rated output" or "rated capacity," and it is assumed to be 1,000 watts (or 1 kW) of sunlight for every square meter of solar panel.

Most residential solar panel systems have a power range of 1 kW to 4 kW. And you can use the solar rooftop calculator to determine your solar capacity.

Solar Panel Efficiency

Most silicon-based solar cells today can convert roughly 20% of incident sunlight into usable solar energy, allowing solar panels' power output to approach 400 watts. High-efficiency solar panels will often generate more electricity for your home because more efficiency equals more energy.

Solar Panel Size and Solar Cell Count

Solar panels can be divided into two size categories: 60-cell and 72-cell solar panels, for easy determination of how many solar panels you need and how much energy your solar panels can produce.

Typically, 60-cell solar panels measure 3.25 feet by 5.4 feet wide and produce between 270 and 300 watts. On the other hand, the average output of 72-cell solar panels ranges between 350 and 400 watts, which is more extensive due to the additional row of cells.

Instead of being used as residential solar panels, 72-cell panels are typically used on larger structures as commercial solar panels.

Your roof location

The latitude of the US is 37.0902° N, which indicates that the sun never sets exactly overhead and is always south of your home.

Because of this, solar panels perform best on rooftops that face south. However, they can also be installed on roofs that face east or west.

Your roof angle

An angle of about 30 degrees provides the highest overall performance for a roof.

Shade Availability

Any obstructions or shadows on your roof must be removed because they will reduce your solar panel efficiency.

Your location

How much energy your solar panel produces also depends on where you stay. For instance, different parts of the US receive different amounts of sunlight.

The sunniest location in the United States is Yuma, Arizona. In Yuma, the sun rises and sets in the same direction 90% of the time. Yuma sets the record for the most recorded annual average sunshine with its typical 4300 sunny hours.

Sunlight Exposure

The term "hours of sunlight" describes how long your panels are exposed to the sun each day (or throughout the year). Your actual productivity will increase the longer you spend outside.

How Many Solar Panels Do You Need  

A typical home should have 20 to 24 solar panels installed to offset its electricity needs completely. The accurate calculation for determining the number of solar panels required is the system size divided by the production ratio divided by panel wattage. 

Again, the precise number you'll need to install will vary depending on your location, the solar panel efficiency, how much energy each panel can handle, and your particular energy use patterns. Notably, the cost of solar is directly impacted by the number of solar panels you require for your home.

How to calculate the number of solar panels you need

There are a few things to keep in mind when you begin to determine how many solar panels you need:

  • Consumption of electricity annually
  • The solar panels' wattage that you are thinking about
  • The solar system's production ratio that you're thinking about

You may determine the number of solar panels you need by multiplying your annual electricity consumption by the production ratio in your region and then dividing it by the amount of power generated by your solar panels.

Solar panel output is crucial for your residential or business solar panel system. The cost of a solar photovoltaic (PV) energy system depends primarily on the system's solar panel output when you purchase or install one (expressed in watts or kilowatts). The solar panel output regulates how much solar power you have. 

Take the quiz and learn more about the benefits of installing solar panels.

Joey Cheek
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Meet the author:

Joey Cheek

Joey Cheek spent 10 years on the US National Speedskating Team where he competed in two Olympic Games, winning gold, silver, and bronze medals. He attended Princeton before diving into the startup and tech world. In 2011 he launched a livestreaming platform for sports before leading a team of engineers building next-gen news and content apps for Fortune 100 companies. He is the CEO and co-founder of, whose mission is to move the earth to cheap, abundant, carbon-free energy.

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