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How much electricity does a solar panel produce?

A picture of some solar panels on a roof producing solar energy

The amount of electricity a solar panel produces depends on three main things: the size of the panel, the efficiency of the solar cells inside, and the amount of sunlight the panel gets.

We’ll break down what you can expect from a typical solar panel, and how that power output compares to the power you need for the gadgets and appliances you use inside your home.

How big are solar panels?

When we say “solar panel,” what we’re talking about is a typical silicon photovoltaic panel. These days, most solar panels are about 5 and a half feet tall and a little more than 3 feet wide:

If you look closely at the solar panel in the image above, you’ll notice 60 little squares. These squares are actually individual solar “cells,” which are linked together by wires. The cells are where electricity is made, and the wires carry the electricity to a junction box where the panel is hooked into a larger array.

Why does solar panel size matter?

The more solar cells working in tandem, the more power they’ll create. That’s why the size of the panel matters if you’re trying to calculate how much electricity a panel makes.

Solar panels have been about this size for decades, but modern panels make more electricity than in the past. That’s because panel manufacturers have found ways to improve cell efficiency over time.

comparing solar panel efficiency over time

How efficient are solar panels?

Solar efficiency relates to the amount of available energy from the sun that gets converted into electricity.

Back in the 1950s, the first solar cells were capable of taking 6% of the energy from the sun and converting it into electricity.

If they were configured to be the same array of 60 cells you see in the image above, that would have created a current of about 20 watts electricity, about a third of what would be needed to light up a 60 watt incandescent bulb.

When we originally wrote this page in 2012, solar cells could convert 15% of the energy hitting them from the sun into power. As of 2017, solar cell efficiency is closer to 20%.

If you combine the efficiency of the cells with the size of the panel, you get a number called the “power rating.” In the solar industry, we say “that panel is rated to produce X watts.”

What’s the power rating for an average solar panel?

As of 2017, a typical solar panel produces around 265 watts of power. That can vary based the size and efficiency of the solar panel you choose; you’ll see panels that produce 210, 280, even 320 watts.

More efficient panels are a little more expensive, and are usually only needed if you have limited space on your roof.

Your solar installer will work with you to figure out how many panels you need to produce enough energy for you to use.

It generally matters less how much each panel can produce than how well the whole array performs.

How is a solar panel’s rating calculated?

Your solar panels will have a number listed on the back that indicates how much power they will pump out during ideal conditions. This is called the Standard Test Condition rating (STC for short).

Here’s what a label looks like on the back of the solar panel:

A rating label on the back of a solar panel

To determine an STC rating, solar labs test the panels under ideal conditions called “peak sun,” or 1000 watts of sunlight per square meter of surface. That’s approximately equal to the power of the sun at noon, on a sunny day, at the equator.

In the picture above, the label shows an STC rating of 250 watts for the panel. If that panel received full sun for one hour, you’d get 250 watt-hours of electricity. With 4 panels, you’d get a kilowatt hour. Click here to read more about the difference between a kilowatt and a kilowatt hour.

Solar panel output calculator (kWh)

Even if you live at or near the equator, you can’t expect to replicate these ideal conditions. The amount of electricity solar panels produce depends on average sunlight over the course of a year. If it’s historically more cloudy in your area, there’s less available energy from the sun to convert into electricity.

The first step to figuring out how much electricity your solar panel can produce in a year is to find your place on the globe. If you live in the United States, you can figure out how to calculate the amount of electricity a solar panel produces and how much you can save using our simple solar calculator:

If you live outside the United States, check out Weather Underground’s solar calculator. You can enter your address into it and get specific details about how much sunlight hits your house on average. The calculator also gives the option of entering a specific model of solar panel and the square footage of the panel coverage on your roof.

Solar panel output per day and per month

Using the example above of a 250-watt STC rated panel, if you multiply the 250 watts the panel produces by the number of hours of full sun you get in a day, you’ll get the amount of kwh that panel produces per day. Multiply by 30 days and you’ll get mothly kWh output for the panel.

The average roof in the United States gets about 4 hours of usable sun per day. We know the sun shines more than 4 hours, but “full sun” is a measurement that combines all the parts of the day when the sun is lower in the sky into one number.

Using 4 hours of full sun, gives you this equation: 250 watts x 4 hours. That’s 1 kWh (1,000 watts) in a day per 250-watt panel.

If you multiply 1kWh per panel by 30 days in a month, you’ll find that each 250 watt rated panel will produce about 30 kWh in an average month.

How much energy does a solar panel produce per square foot?

Solar panel output per square foot

The average-sized solar panel takes up an area of 17.6 square feet and produces 265 watts under direct sunlight. That translates to just over 15 watts per square foot.

How many solar panels are needed to power an average house?

Sizing a solar panel system to your home’s electric usage can be done by taking look at your energy bills over a year.

Most utility companies provide information about your last few months of usage on your bill, but you can probably get more on their website. A few lucky customers get a year and a half like this:

a sample energy bill before solar panels with usage details

We’ll spare you the trouble of averaging that column, and tell you that this house uses about 2,200 kWh per month. That’s quite a bit higher than the national average, which means the homeowner could really be helped by solar power!

Typically, homeowners in the United States use about 900 kWh a month on average. So, take 900 kWh and divide by the amount of kWh one solar panel produces over the course of a month (30kWh), and you get a 30 panel installation. 30 panels x 250 watts per panel equals a 7,500 watt system (7.5kW).

Again though, these are just rough estimates. It’s best to connect with an expert we trust near you who can appropriately size a system and help take advantage of all the local incentives to get it done right and as affordably as possible.

How much power do my devices use?

There’s huge variation in power use between households depending on what you own and how often you use everything. People in the South and West United States tend to use more electricity for heating and air conditioning, whereas people in the North and East tend to heat with gas or fuel oil.

One basic old-fashioned lightbulb uses 60 watts of electricity; a CFL uses 18 watts. Laptops often use about 45 watts, and desktops can run between 150-300 watts. Window air conditioning can range between 500 and 1500 watts, and central air conditioning can use 3500 watts.

The average home in the US uses about 1,000 kWh of electricity per month. All those little devices add up to big usage, with variations by season. Usage also varies between day and night. Unless you work at home, most of your electricity usage probably happens at night.

On or off the grid?

Since solar panels only generate power as the sun shines, you’ll need a way to store the energy. Though it’s possible to use a battery for storage, the easiest (and cheapest) solution for most people is to stay connected to the grid.

If your solar panels are producing more energy than you’re using—when you’re at work, on vacation, or just not running many devices—excess power will flow back into the grid. In many locations, utility companies offer a program called “net metering” that can compensate you for extra power you produce.

At night, or anytime you need extra power, you’ll pull it from the grid. With a grid-connected system, you’ll never need to worry if you happen to need more power than your solar system has been sized to provide. You may also choose to supply only part of your average electricity bill with solar, and use the grid for the rest.

Your solar installer will talk to you about all of the options. Interested in getting a quote? Sign up with us to get a free consultation.

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76 thoughts on “How much electricity does a solar panel produce?

  1. Mohamed Abdulhaq says:

    Hi…Can I have power using solar panels directly connected to an inverter without using batteries?? since I only need power for about 5 hours during the day. my power consumption is about 2.5 kw which requires about 12 panels of 260 watts each and maximum 4 to 5 kw inveter

  2. Anonymous says:

    I have a question. I am in Nunavut trying to build a mini solar panel for a science fair project. In total it is 54 volts and trying to generate 3 light bulbs in a parallel circuit. How long would it really take to light up the three light bulbs?

  3. Imdad from Pakistan says:

    a system with: 1800 W (150 w each mono panel in shape of array 2*6); 24 volt battery bank (100 Ah each deep cycle, type lead acid, 4 batteries (2*2)); PWM charge controller; in present days in month of July, receiving 4 to 6 kwh in a clear day but mostly 5 kwh; at noon usually 1100 w, but once noticed 1295 w; do I suppose my system is working good or may I shift to MPPT charge controller?

  4. Anonymous says:

    Spelling and grammar matter people…if you want to be taken seriously.

  5. elijah osiemo says:

    wish to run mini bakery and need 50KW power supply . how many panels do i need to install and long can they last supplying effectively?

  6. Rusty says:

    I have a 1.2 KW System in fun sun all day. The best I average is 2.5 KWh a day in Kansas and it runs a Frigidaire FFRE0533Q1 5,000 BTU airconditioner for about four hours. And my battery bank is four 100ahr agm. 24V system. Dont expect more than 550W peak from 12 100w panels. I have an eppsolar mpp controller.

  7. bh says:

    I like to run off grid a small AC window unit 8,000 BTU, 120 V 15 AMPS. How many solar panels and batteries do I need?

  8. Virendra kumar says:

    I had installed 5400W solar panel with 5kW grid tied inverter. Our maximum power generation is limit to 3200W. we had installed 5400W panel. I think this is too low.

  9. Anonymous says:

    just wow

  10. patel ashok says:

    I am intrested to know, if solar panel can work on cloudy wather , is it possible that if i installe solar pannel on dack which is covered with glass roofroof to get sufficent sun light and at night with light which is normally on during the night time.

  11. Ruwan says:

    I have about 160 perch land. how meny solara panel install it. how meney power get it

  12. Anonymous says:

    I have 2500 watt,24 Volts solar panels- I want to know what is the current it produces

  13. Jacobus Maximus says:

    Ugh. I’m just looking for averages. If I have 1000 sq ft of “roof space” and want to put solar panels on my house, what am I looking at as far as cost savings? Ideally, the house would be completely powered by solar, but I know that won’t happen (since we live in Oregon and it rains 9 months out of the year,) but I want to know what the offset will be. Right now, living in an apartment, our electricity bill is about $60 a month. We can run our AC 24/7 when it’s hot as hell and our bill stays the same. But during the winter, we dress for base camp to hike Everest and it’s still like $80 per month. I want to live at a comfortable 65 degrees year round…

    1. Ben Zientara says:

      yo

  14. Chico Escuala says:

    The wattage rating you quote per panel is what is called “nameplate” power. It is the DC power as measured under perfect conditions at high noon on a cloudless sunny day at the PV panel DC ports. That power is diminished further by what is called the DC to AC “derate” factor. This factor typically diminishes power by 1/3. In other words solar companies are reluctant to tell you the actual available solar power at the AC outlets in your living room. This power is about 150 watts at the AC outlet where you plug in your appliances.Also solar energy will vary from day to day. This means you will see about 20 cents worth of power on a good day and about 2 cents on a poor day. Averaged over a year your total power output per panel will be about $35. The question now is: are solar panels worth the trouble and expense? You be the judge.

  15. Nikhil says:

    I need 2000 kWh per month , so how many pannels and how much area do i need.

  16. S.R.BUILDERS says:

    WE ARE PLANNING FOR 1 MW SOLAR POWER PLANT. PLS GUIDE US HOW TO EXACTLY FIND A GOOD LOCATION WITH HIGH SOLAR RADATION IN OUR STATE OF ANDHRA PRADESH, INDIA.

    1. Ben Zientara says:

      Hello! The place you’re looking for has to have a few key factors:

      • No shade; so a low, relatively flat south- or west-facing hill with no trees surrounding it is ideal
      • Solid ground to mount the frames into
      • Some kind of transmission infrastructure built in the area, to get the power to the grid

      Good luck!

  17. Zeidy says:

    I live in Costa Rica and want to install an off grid solar power system to run a 220 deep well pump for approximately 4 to 5 hours per day. How do I know which panels inverter etc, I need?

  18. Manish Kumar says:

    I want to install a solar panel at my shop which need 3 KV power to run it. Roof area is 10ft x 10ft.

  19. Jacek says:

    Hi, I’ve got a 50ft x 20ft southern facing sloped piece of land on the back end of my yard that is too steep to play on, but would probably make for a great Solar Farm site. If my local utilities company will rebate me $0.25/watt, what is my best course of action (type of panel, size of panel, number of panels, etc.) if I am willing to use that entire piece of land to make energy?

  20. Jesse says:

    If your most effiecient panel produces 300 watts, how many kwh will it produce?

    1. Ben Zientara says:

      Hi Jesse-

      That depends on where you are in the world and how much shad you have. For example, an un-shaded 300W panel in New York City would produce about 1 kWh per day (averaged over the year), whereas the same panel in southern California would 1.25 kWh per day. We have a pretty neat calculator that you can use to test the production of solar panels at the bottom of this post: https://solarpowerrocks.com/square-feet-solar-roof/

  21. nada ainiah says:

    which right way to connect the cell << parallel or series

  22. Gaby says:

    How much sunlight is produced per year

  23. Ramon says:

    How many solar panels would I need to get for an average of 2,078 KWH monthly?

  24. Anonymous says:

    It says how much a panel produces but like in what time period? So 200 kilowatts per hour or…??

    1. Ben Zientara says:

      The panel rating is basically the peak output at any given moment under laboratory test conditions. If a 200-kW panel was to generate its maximum output for an hour, it would equal 200 kWh, yes.

  25. Ak says:

    how much do I need solar panel and which size, if my electricity bills comes around 450kWh

  26. douglas ryan says:

    How many MW can a 60KV line carry?

  27. horu says:

    Can you give a rough idea, the required number of solar panel (with power capacity) for daily power consumption 2,400 KWh, for the location Rai, Sonepat, Haryana (India)

    1. Ben Zientara says:

      Hi, horu. If your site needs 2,400 kWh/day, you’re going to need a whole bunch of solar panels. Like more than 4,300. If it’s more like 2,400 kWh per year, you need about 12 solar panels. You can do some more calculations with our calculator located about halfway down this page: https://solarpowerrocks.com/square-feet-solar-roof/.

      Good luck!

  28. Khan says:

    Thanks for technical support .I am going to install a 100 kw On Grid solar system in Karachi which is Ideal for solar Energy. but could not get the actual performance of the system. means what will be the outcome in a day/week/year in kwh. Irradiation rate is 4 to 5 kwh/sq.meter/day

  29. mathew.stoddart@ca.weatherford.com says:

    What would someone need to power a three phase 50hp electric motor? I’m curious because i would like to try and power an oil well with solar panels.

  30. salim says:

    question….how many solar pannels can be used to drive a DC motor of 75kw?

  31. Ben says:

    If my usage is 4966.92 kwh every month give or take whats the best ideal set up for me to power my whole house

  32. Ross says:

    power up a e-bike wheel if it takes 48v 50a. off power and have 10 panels that put out 24v 5a each and i run them 2 in sires and 5 in parall would this run the wheel????

  33. Anonymous says:

    Avgw panel 200 watts.. Harbor freight 15 wants what am I missing ?

  34. Anonymous says:

    I am trying to power individual growing towers for food. This requires that I have a sump pump at the bottom of the tower to pump the water up to 10 ft. The sump pump I have found to do this job uses 4 Amps @ 120V. The estimated G/Wh(gallons per watt hour) is 6.25. What kind of solar powering device could I use to power this growing tower off the grid?

    1. Ben Zientara says:

      Watts = volts x amps, so you need panels capable of putting out a continuous 480 W. That means you’d probably need at least 3 panels of around 180-200 W each (extra to compensate for losses due to wiring, etc.), plus microinverters. But they would only operate the pump when the sun was shining on them. You could add one of Tesla’s new Powerwall batteries for $3,000, plus a couple of extra panels to maximize capturing energy, but then you’d be looking at $10,000 just to power a pump.

  35. Anonymous says:

    Over a 12 month period, I use 14,500 kwh. How many solar panels I need to produce that much energy?

    1. Ben Zientara says:

      14,500 kWh is a little above average, but not too much. How much your panels produce really depends on where you live in the U.S. For example, on the east coast, you’d need a 12-kW system, which would mean about 54 panels, which would be about 740 square feet of roof space. In California, it would be more like a 10-kW system, or 45 panels taking up about 616 square feet.

      Really though, you don’t need to offset your entire usage with solar. Net metering from your electric company means you can have any sized system and see proportional savings.

      Hope that helps!

      -Ben

  36. Anonymous says:

    i use about 65,000 kw per month, how many panels would i need to have $0.00 elect bill.

  37. Anonymous says:

    Kiara says: my school is using 123,840kwh per month how many solar panels and should we get the 250 or the 350kw panels

  38. Anonymous says:

    will I qualify if my house uses 70kwh per month or more???

  39. Anonymous says:

    Guys ! no one here has answered a simple question , I calculated that each house on average in US uses 30KW a day , so the question is how many sq feet of PV panels do I need to install to suppy a full day of power for an average home (30kw)?

    1. Ben Zientara says:

      Hey there, friend. We have a page on our site that answers this exact question, with lots of good information about what it all means. Check out “How Many Square Feet do I Need for Solar Panels on my Roof?”

  40. Anonymous says:

    Has there been any changes in the duribility or storage capacity as it relates to batteries?

  41. Anonymous says:

    To the commentor stating that voltage is the correct unit for consideration: Voltage between two points is a measure of the potential energy a unit charge gains or loses between two points. The voltage function and electric fields can be gotten from one another. Thus, the voltage can be thought of as correlating to the strength of the electric field (I won’t go into the vector calculus of conservative force fields). “Power” is defined in physics as the rate of energy change, or time derivative of energy, however that energy is defined for a system. If E is energy, then power := dE/dt, that is the mathematics of the situation. So, while voltage is indeed a quantity you must consider, “power” has a specific definition in physics that is not as you describe it.

  42. Anonymous says:

    I read several posts here and I find that too many people are not asking the correct questions. When solar cells produce power you measure that power in voltage. Many different solar cells produce various volatges. This all depends on how many solar cells are “ganged together” A large solar cell can be a combination of voltages based on whether they’re wired in series or parallel.

  43. Anonymous says:

    Im trying to work out the plans for building a tiny house. It will be about 175sqft. With a roof pitch of 12/9. Im curious how many solar panels i will need, ir if it is even possible to power my home on just solar. I live in upstate Ny, and the home will have lights, efficient tankless h/w heater, 10cuft fridge, and electric stove top. Also some outlets for charging phones and things.

  44. Anonymous says:

    Will a 100w panel run a good size fan in my green house during the day i live in kentucky.

  45. Anonymous says:

    1.21 gigawatts? You know what that means? It means your stuck.

  46. Anonymous says:

    I want use one ton window air-conditioner at least for 10 hours long, and use iron box of 2000 watts and refrigerator of 300 watts for 24 hours and 20 cfl lamps for 6 hours long. How many solar panels do I need and how many batteries with how much ampere? Sun is available for 6 hours long. Can some one give information?

  47. Anonymous says:

    I have 350 watt solar panels and inverter 1500 watt 12v – 120v, can I run a small portable ac 1000 watt ? Do I need more solar panels? Please help, Thank you…

  48. Anonymous says:

    I live in india, I have four solar panels. Can I get enough juice out of them to power my tv?

  49. Anonymous says:

    We live in Dallas, Texas and have installed 29 panels facing south on our roof. I believe that they are 250 watt panels. How much energy will they produce in a month?

  50. Anonymous says:

    I have been visiting several websites and cannot find the answer to my question. I have a small house, 613 sq ft, I live in Costa Rica; so we gets lots of sunlight. My utility bill is around $35 a month. We do not have A/C, but am thinking of getting one and it would be European style. I use on average about 225 KWh per month. What type of system would I need? It’s hard to find a site that will let me factor in for living here. Thank you for helping me out.

  51. Anonymous says:

    Working on a time machine all I need is 1.21 gigawatts of electricity…

  52. Anonymous says:

    i require 3500 watt hour per day.. How many panels are required if sunlight hour here is 5. please reply fast

  53. Anonymous says:

    I,m getting 12 250 watt panels I use about 350 kwh a month is that enough

    1. You are probably right at where you want to be. Assuming a 30 day month, you are using a little under 12 kilowatt/hours per day. (Congratulations by the way on minimizing your electricity demand!) A 3 kilowatt system will probably produce an average of about 15 kilowatt/hours per day. Obviously that will vary depending on if you are in Maine of Texas, but it’s a good rule of thumb. There will be some losses along the way from the inverter, wiring and so on so a 20% overproduction is about right. If you are in a northern state you might want to bump it up a bit if your goal is to produce 100% of your electricity, but here’s the thing: You can always add a few more panels. Having extra electricity production only makes sense if you are currently unhappy with the lifestyle that has gotten your usage so low, and you would welcome the opportunity to use a bit more electricity. For example, if you would like to add a window air conditioner, you would probably welcome a bit of extra electricity flowing through your wiring!

  54. Anonymous says:

    sir, i have 374w solar panel 1x200w 1x80w 2x37w and dirrectly connected to 150ah flat battery. but battery is not take full charge in a day is goes to 1150 as per hydromatter which is require 1250, regards Wasti

    1. There are a couple of possible issues. It’s unlikely to be a problem with the panel, they are pretty foolproof, but it wouldn’t hurt to test the output and see if you are getting the amps you think you are. It’s more likely to be an issue with the battery. Batteries start with a ~95% efficiency but that can fall to 50% depending on the battery’s age and the usage. If I had to guess, based on the information provided, I would guess your battery has some sulfur from the sulfuric acid bonded to the battery plates, and that’s reducing the efficiency of the battery. You can buy a Battery Tender pretty cheaply online and hook the battery up until the light glows green and pulses. This may take a few days, depending on the condition of the battery. After that, you can use the Battery Tender periodically to maintain the battery. It’s possible the battery is too far gone, and you may need a new battery, if that’s the case, use the Battery Tender as often as you conveniently can to avoid damaging your new battery. In general, the best way to keep your battery happy is to keep it as charged as possible and to drain it as little as possible before recharging it. I hope that helps!

  55. Anonymous says:

    hello, if i want to fixed the numbers of panel is required to run some high powered electrical components like pump,fans(DC/AC) etc then which strategy or calculation i have to follow?

  56. Anonymous says:

    How much energy would 1,180 miles of solar panels produce opposed to the Keystone Pipeline?

  57. Anonymous says:

    can we set glasses in accordance of angle of reflection and merge the sunlight towards solar panel for more efficience of electricity

  58. Anonymous says:

    how can i calculate the amunt of power produced from a single pannel of solar energy

  59. Chiremba E says:

    A useful analogy is the difference between speed and distance. Speed is distance travelled in unit time. Distance total distance travelled over the period in question. Similarly, power is energy delivered per unit time, usually per second. Power is measured in Watts or kiloWatts (thousands of watts). When a device delivers power at a rate of 1 kW continuously for one hour, the energy delivered in that hour is 1kWh. For 2 hours, it’s 2kWh. If instead the device was delivering 0.5kW for 5 hours for example, total energy delivered is 2.5kWh, being 0.5kW * 5h to give 2.5kWh. Hope this helps.

  60. heem says:

    my country is very hot,can i use air condition 2000watt ? how long time can i use?

  61. heem says:

    How much kilowatt my solar system will provide me monthly ?

  62. Sam says:

    Power is the amount of energy used per unit time. Thus Energy used is power * time. Thus ‘kilowatt hour’ is simply power in kilowatts * time in hours

  63. Kati says:

    So, on average, how much energy (in kilowatts) is produced an hour?

  64. Bonzo says:

    Please, differentiate between Kilowatts—which measure Power, and Kilowatt hours which measure Energy. Clearing this obfuscation will help people to make more intelligent decisions about the energy they use and hopefully produce

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