solar panel output energy production

How much energy does a solar panel produce?

Most solar panels on the market in 2022 produce between 250 and 400 watts of power. You might come across these solar panel output numbers from your solar installation quote, which will typically include “245W”, “300W”, or “345W” next to the name of the panel. They are all referring to a solar panel’s wattage, capacity and power output.

Key takeaways about solar panel output

  • Currently, most solar panels on today’s market usually produce between 250 and 400 Watts of power — your actual output will depend on factors like shading, orientation, and sun hours.
  • With a 30-panel system, you’ll be producing more than enough electricity per year to match all of your electricity usage, and maybe more!
  • You can freely compare solar quotes on the EnergySage Marketplace to see how different wattage panels will affect your unique system

What’s in this article?

How to calculate how much energy a solar panel produces

All solar panels are rated by the amount of DC (direct current) power they produce under standard test conditions. Solar panel output is expressed in units of watts (W) and represents the panel’s theoretical power production under ideal sunlight and temperature conditions. Wattage is calculated by multiplying volts x amps where volts represent the amount of force of the electricity and amperes (amps) refer to the aggregate amount of energy used. 

Most home solar panels on the market today have power output ratings ranging from 250 to 400 watts, with higher power ratings generally considered preferable to lower power ratings. Pricing in solar is typically measured in dollars per watt ($/W), and your total solar panel wattage plays a significant part in the overall cost of your solar system.

For example, if you are getting 5 hours of direct sunlight per day in a sunny state like California you can calculate your solar panel output this way: 5 hours x 290 watts (an example wattage of a premium solar panel) = 1,450 watts-hours, or roughly 1.5 kilowatt-hours (kWh). Thus, the output for each solar panel in your array would produce around 500-550 kWh of energy per year.

how to calculate solar panel output

What factors determine solar panel output?

Before calculating the amount of energy a solar panel can produce, it’s important to understand the two key factors that determine its power output: cell efficiency and solar panel size.

Let’s assess each factor separately to understand them a bit better.

Solar panel efficiency

Today, most silicon-based solar cells can convert about 20 percent of the sunlight that hits them into usable solar energy, which has led to panels exceeding 400 watts of power. Higher efficiency = more energy, so high-efficiency solar panels generally will produce more electricity for your home.

Number of solar cells and solar panel size

To make things easy, we can divide solar panels into two size groups: 60-cell solar panels and 72-cell solar panels. Usually, 60-cell solar panels are about 5.4 feet tall by 3.25 feet wide and have an output of about 270 to 300 watts. On the other hand, 72-cell solar panels are larger because they have an extra row of cells, and their average output is somewhere between 350 to 400 watts. 72-cell panels are usually used on larger buildings and in commercial solar projects, not on residential homes. 

average solar output and what impacts it

Environmental factors: shading, orientation, and hours of sunlight

Solar panel efficiency and the number/size of solar cells in a solar panel are factors that directly impact the rated power of a solar panel. In the real world, there are a few more things that impact how much power a panel will actually produce:

Shading of your solar panels will lead to lower production. Solar panel wattage ratings do not take into account the lowered output of a panel when there’s shade blocking the sun.

Orientation of your solar panels also impacts production in a way that a panel’s output rating doesn’t capture. Ideally, your panels will be angled directly towards the sun. In practice, roof planes are almost never perfectly angled for maximum production.

Hours of sunlight simply refer to the amount of time per day (or year) that your panels are exposed to sunlight. The more hours in the sun, the higher your actual output will be.

What can you power with a single solar panel?

In the example above, the solar panel is producing 1.5 kWh per day, which is about 45 kWh per month. That’s enough energy to power some small appliances without too much issue, but if you want to cover the energy used by your property’s climate control systems or large cooking appliances, you’ll need more solar panels. Check out our article on how many solar panels you need for your home to better understand how much solar energy your unique property needs.

How much energy will an entire solar panel system produce?

Knowing how much energy a single solar panel produces is all well and good, but more importantly, how much solar power can your roof generate? Let’s do the math below:

Take our example above, where you’re getting an average of five hours of direct sunlight per day (an average amount of sunlight for most areas of California) and using solar panels rated at 290 W. Let’s say you install 30 of those premium solar panels on your roof–that nets you an 8,700 watt, or 8.7 kW solar panel system, near the average system size purchased on the EnergySage Marketplace. Multiply the five direct sunlight hours we estimated above by 8.7 kW, and we get approximately 43.5 kWh of electricity produced per day. And for one final conversion, if we multiply 43.5 by 365 days in a year, we get approximately 15,800 kWh of electricity produced in a full calendar year from a rooftop array of 30 premium, 290 W solar panels. Considering that the yearly average for electrical power is around 10,600 kWh in the U.S., that’s probably more than enough to power your home on solar.

This estimate is likely on the high end for most solar shoppers, and likely because of our estimate for the amount of sunlight the system will get (known as sun hours). To learn more about average sun hours, check out our blog here, where we take a look at average sunlight per year by location.

Solar panel output by product

With so many solar panel manufacturers out there, panel output varies significantly between brands and products. In 2022, these are the top six solar panel brands in the U.S. ranked by their maximum power output panel:

  1. First Solar (460 W)
  2. LONGi (455 W)
  3. REC (450 W)
  4. SunPower (435 W)
  5. Q CELLS (430 W)
  6. Solaria (430 W)

The table below presents a view of power output from many manufacturers supplying solar panels to the U.S. market. Because panel manufacturers often produce more than one line of solar panel models, the power output of most companies has a significant range. The table below lists the solar panels’ minimum, maximum, and average power outputs within each manufacturer’s portfolio.

Electricity output (in Watts) of solar panel manufacturers

Solar Panel Manufacturer
BenQ Solar (AUO)250295277
Boviet Solar320340330
Canadian Solar225410320
CertainTeed Solar70400308
ET Solar255370306
First Solar420460440
Grape Solar160285237
Green Brilliance230300266
JA Solar260410329
Mission Solar Energy300390334
Mitsubishi Electric270280275
Neo Solar Power310330320
Peimar Group270330301
Phono Solar260350294
Recom Solar310350330
Renogy Solar250300268
RGS Energy556058
Solartech Universal310325318
SunSpark Technology310310310
Talesun Solar Co.400400400
Trina Solar Energy260320288
Vikram Solar320340330

Why does solar panel output matter?

Power output is an important metric for your home or commercial solar panel system. When you buy or install a solar photovoltaic (PV) energy system, the price you pay is typically based on the solar panel output of your system (expressed in watts or kilowatts).

Solar panel wattage represents a solar panel’s theoretical power production under ideal sunlight and temperature conditions. Wattage is calculated by multiplying volts x amps where volts represent the amount of force of the electricity and amperes (amps) refer to the aggregate amount of energy used. For systems that are grid-tied, open-circuit voltage and the voltage of your system may not be as significant of an issue. For those that are off-grid or wish to utilize battery storage, however, it’s an important part of your PV system. The financial savings you derive from your solar system result from the electric energy it generates over time (expressed in kilowatt-hours).

How do size and quantity impact output? 

Power output on its own is not a complete indicator of a panel’s quality and performance characteristics. Some panels’ high power output rating is due to their larger physical size rather than their higher efficiency or technological superiority.

For example, if two solar panels both have 15 percent efficiency ratings, but one has a power output rating of 250 watts, and the other is rated at 300 watts, it means that the 300-watt panel is about 20 percent physically larger than the 250-watt panel. That’s why EnergySage and other industry experts view panel efficiency as being a more indicative criterion of solar panel performance strength than solar capacity alone.

In practical terms, a solar panel system with a total rated capacity of 5kW (kilowatts) could be made up of either 20 250-Watt panels or 16 300-Watt panels. Both systems will generate the same amount of power in the same geographic location. Though a 5kW system may produce 6,000 kilowatt-hours (kWh) of electricity every year in Boston, that same system will produce 8,000 kWh yearly in Los Angeles because of the amount of sun each location gets each year.

The effect materials have on output

Solar panels can be made from either monocrystalline or polycrystalline cells. Monocrystalline cells are more efficient and able to generate more electricity than polycrystalline cells. However, polycrystalline solar panels are much more affordable.

The electricity generated by a solar PV system is governed by its rated power output, but it’s also dependent on other factors such as panel efficiency and temperature sensitivity, as well as the degree of shading that the system experiences and the tilt angle and azimuth of the roof on which it’s installed. As a general rule of thumb, it makes prudent financial sense to install a solar system with as much power output as you can afford (or that your roof will accommodate). That will ensure you maximize your savings and speed up the payback period of your solar energy system.

Find out more about average prices for solar across the country for 3kW,4kW5kW6kW, 7kW8 kW, and 10kW solar systems. The EnergySage Solar Marketplace makes it easy for you to compare your savings from solar panels with various power output ratings.

Common questions about how much energy a solar panel produces

Because few people own just one solar panel, we talk more about the system output than individual solar panel output. Here are some of the questions we are frequently asked surrounding how much energy solar panels, and solar panel systems as a whole, generate. 

How many solar panels do I need for 1000 kWh per month?

This depends on weather conditions, how much sunlight a location gets, and solar panel output. It would take about 27 solar panels to produce that much electricity in ideal conditions with the average solar panel.

How much does a 300-watt solar panel produce?

A panel of this size would produce between roughly 1.2kW to  2.5kW per day. Solar panel output and the amount of sunlight available will impact how much energy it produces.

How much power does 5kW solar produce?

If exposed to the sun at least four hours a day, a system of this size can produce up to 20kWh per day.

How much energy do solar panels produce per hour?

The average solar panel produces from 170 to 350 watts every hour, depending on the region and weather conditions. This works out to about 0.17 kWh to 0.35 kWh per solar panel. 

Explore your solar options today with EnergySage

If you’re in the early stage of shopping for solar and would just like a ballpark estimate for an installation, try our Solar Calculator, which offers upfront cost and long-term savings estimates based on your location and roof type. For those looking to get and compare quotes from local contractors today, check out the EnergySage Marketplace.

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72 thoughts on “How much energy does a solar panel produce?

  1. Whatcom Window Cleaners

    I love finding extremely specific and informative articles such as this one to send my clients’ ways when asked specific questions about products such as solar panels. We do maintenance cleans and that’s the majority of what we specialize in as far as solar panel knowledge, but we do like to let clients know that maintaining the panels’ cleanliness can result in optimal energy!
    I will definitely be directing my clients to this article, and I appreciate you putting together the time and energy to publish this.

    1. Gary Scharphorn

      If a single PV panel produces 400 watts continuously for an hour, this is 400 watt hours (0.4KWh). The output per day or month will depend entirely on the amount of sunlight the panels receive.

  2. thomas harris

    would like to purchase all the components to build in place small power planet I have background heavey highway bridges hydro eltiric biomass stream generating plant high power line corridor transmission line I do have the ability to design and build on the fly can have the nessatary plans and engineering to jget this one if goes well i see this repeating over and over Ilook forward to building a few ot this high caliper designbuild project

  3. Mike Lopez

    Unfortunately, solar panels won’t perform the way they do in lab-controlled STC in the real world. Between how the solar panels are installed, the weather in your area, and the other equipment that makes up the solar system, your panels will produce less than the wattage rating.

    1. Richard Jacobsen

      That is true. To get us to the other side of the clean energy needs. It will have to be multifaceted, Nuclear, Petroleum, Solar, Wind, and Water. No single source will solve this. The 2 biggest problems are not technical they are infrastructure and getting congress off their ass.

  4. Craig Fisher

    Good article with a straight forward explanation, making it easy to understand. So many people don’t take the time to explore the cosmetics of a on or off-grid solar system. They tend to make assumptions that are laughable to those who have researched and done our due diligence in learning what solar power systems can or cannot do. I commend folks, like you, who have the patience and knowledge to advise those who have primarily questions made from assumptions. The perceptions of solar, by some people’s questions, I find hilarious. I’m glad there’s people who can answer them and keep a straight face.

  5. Mick

    Great article. We have customers asking us about solar output all the time – it would be great for anyone interested in solar panel installation to read up on this!

    You cover the basics such as calculating Wattage and the influence of the sun/geographic location, which all customers should know before purchasing. The tips you give are very genuine and useful for both sellers and consumers. The crunch of the article for me was stating that the best option when considering what to buy is to buy to the one with the most power output within budget.

    Listing the brands was so handy for our company as we’re at that point of choosing our products. We wanted to know which brands produce the most electricity, and you covered that. This has been a great help – thank you.

  6. Jerry Cousin

    If I want to use an immersion heater to prevent 250 gallons of water from freezing for a period of winter from November to the end of March what size of panel is required and can the immersion heater be connected directly to the solar panel or are other components required?

    1. Joe

      Consider using Thermal Solar vs. PV. (heat the water)
      Set up a drain back panel system. (so you don’t need anti freeze)
      Run the 12V circulator on a small PV panel.
      Insulate the water storage tank. (maybe build a shed or move inside)

      You need a serious PV system to run an immersion heater.

  7. Bill Hankla

    How many solar panels are required to create enough energy to produce a solar panel in one day?
    Measured in KW, how much energy is required to produce a solar panel? Consider mining of all raw materials, transportation, processing, fabrication of raw materials, facility costs, installation. What is useful life of the panel and how much energy is produced by the panel in that life time?

    1. George

      Absolutely right question. I would like to know this as well. Most probably much more than any conventional (nowadays) source of energy. It won’t be so easy to go eco. In any case it is inevitable – it will be expensive and less should be used.

  8. Heizen Black

    You can see a label indicating the maximum power output from each of your solar panels. A solar panel’s highest capacity to generate power in optimal conditions in a laboratory is the basis for the wattage assigned. The process is called STC or Factory Standard Test Condition. When used in actual conditions, there’s an expected performance drop which is known as PTC.

    The amount of sunlight the panel gets and the location are the power output determiners. Nevertheless, this output is not the same all day or the period where there’s sunlight. Compared to the middle of the afternoon, it creates less energy in the morning or late afternoon.

    If there’s a shade such as clouds or anything that covers a portion of the whole module, it can lessen the generated power of the panels. Since there is a change in the sun’s position, there’s also less output during the summer and spring compared to fall and winter.


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