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. Alan Fine

    For the question
    Take for example this panel: SunPower Corporation E-Series Commercial SPR-E20-435-COM. It generates 435 W and is 2 square meters. So that is 217 W/m2. Now, if efficiency is around 20%, then the available radiation must be 217/0.2 or about 1,000 W/m2.
    But according to the climate change reports I read about radiative flux, the incoming shortwave solar radiation striking Earth’s surface is only 160 W/m2. What gives?

    I think the answer is that although only 160W/m2 falls on the earth, the peak can be 1000W/m2. I think these panels may be rated that way. The actual energy is 1361 W/M2 so i guess on average you loose 1/4 day-night and sphere effect. Given no clouds the max people find I guess is 1000W/m2. but it can be as small as 100W/m2 depending on the clouds. So not an expert but that is a possible answer. Very good question, I had the same concern.

  2. Heizen Black

    wanted to help my sister after Hurricane Maria. It has been over 6 months that she has not had power. I put together a system that I could order from Amazon and send most of the components to Puerto Rico directly. I ordered the SolarEpic 40A MPPT Solar Charge Controller, four Uni-Solar PVL-136 PowerBond PVL 136 Watt Flexible Solar Panels, a POTEK 2000W Power Inverter Three AC Outlets 12V DC to 110V AC and the miscellaneous cables and fuses. I prewired the controller and the inverter and wrote a detailed set of instructions on how to connect everything else. Luckily, I found in PR the batteries at Batteries Plus, and I ended up using two 12 vdc 155 Amp-hours for the project. My sister and my nephew installed the system and it has been powering her fridge, a few LED lights, a fan and charging phones and computers since with no problems. These products are outstanding and provide very impressive performance.

  3. Heizen Black

    I successfully completed a 3 day camping with this along with a Goal Zero Yeti 150. I was able to top off the Yeti from 60% to 100% within 3 hours. This is with it in direct sunlight and 10% cloud coverage and ambient temperature of around 90degrees F. I’m not sure how much of the temperature impacts the performance but I thought it would be worth noting.

  4. Thomas


    Great article.

    I just got my solar panels installed (21 Panasonic 340w) 7.1 KW system, which was activated last week. I’m still waiting for the final inspection approvals before my utility company will recognize it. I also got Tesla Powerwalls installed, but they have not been activated yet. I haven’t gotten access to the solar app (Enphase) yet from the installer, but can monitor the total output in my Tesla App. Here is my question:

    Conditions: I live in sunny Los Angeles! California. 16 of the solar panels are installed directly towards south and 5 of them towards north (I understand they are less efficient). 20 degrees slope following my roof.

    Friday – and the first full day of observations in my Tesla App – we had a clear day and I observed solar generation between 7am and 6pm. The peak real time kw was no higher than 4.8 kw. I generated 32 kWh during the day. Is that normal for a 7.1 Kw system on a clear day in mid October on day 1 for a system as described above? I understand it can be normal to have a loss of 20%, but that should bring my peak to 5.5kw and not 4.7? Thank you in advance.

  5. Thomas W

    Take for example this panel: SunPower Corporation E-Series Commercial SPR-E20-435-COM. It generates 435 W and is 2 square meters. So that is 217 W/m2. Now, if efficiency is around 20%, then the available radiation must be 217/0.2 or about 1,000 W/m2.
    But according to the climate change reports I read about radiative flux, the incoming shortwave solar radiation striking Earth’s surface is only 160 W/m2. What gives?

  6. Bala Ibrahim Girku

    Great questions and answers!!!
    Please would like to ask, how many square foot or square meter area would be required to house panels that can generate 1megawatts of power?

  7. Nitin

    I have Rooftop which is accomodating 117 kw ( of 330 w panels) .

    If i put 550 w or 580 w panels on that same space, will it provide the higher power generation than 117 kw ? if yes, how much more ?

    1. Dan Hoskin

      People by solar by the KW, or the maximum amount of energy the panel produces in an instatnt, but the utility charges for kwhr, or how much energy you use per hour. Panels can produce 1500kwhr/ kw purchased, or 1800kwhr/kw purchased. A panel that produces more Kwhr/kw purchase saves you more on your electric bill for each dollar you spend per KW of solar energy. Panel size does not matter as much as this. I hope this is helpful. I have met many solar guys who don’t understand this.

  8. Kevin

    I have a 70 watt Npower solar panel to charge my 12 volt camper battery and the open circuit is 41 volts and voltage out of the charge controller is 38 volts is that normal

    1. LWAW

      Yes, it’s normal. If your inverter will generate a lot of heats. Its normal. Also cable will consume some power. My test with Grade A panel and amazon 1000w cheap inverter. Maximum out put is around 66%~72% and you are at 58%.


    The Moore/Gibbs fiction-mentary is pure loaded garbage. Their case is so devoid of substance that they made sure that they evaded ALL technological progress of the past 15 years. How convenient to make a case based on early 2000s tech and even then they show totally misguided examples. Such as that solar farm in Michigan that installed panels that were mean’t for RV camper homes in the early 2000s. Those panels were neither appropriate or representative of either home or utility solar panels even of that time. Panels sold today are light years beyond them.

  10. Peter Christopher Dung

    Can I get a book or a link to guide me on rating solar panels wattage side by side with the voltage rating?


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