power output of a solar panel

How much energy does a solar panel actually produce? Electricity output explained

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Power output or wattage is an important factor to consider when comparing solar panel options. You may hear your solar installer say, “it’s a 255 Watt panel” or “the panel I am recommending is has a wattage of 300.” Or, when you are reading a quote from a solar installer, you might see numbers like 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.

Find out what solar panels cost in your area in 2020

Key takeaways about solar panel output

  • Solar panels usually produce between 250 and 400 Watts of power
  • The actual output you see depends on factors like shading, orientation, and sun hours
  • You can freely compare solar quotes on the EnergySage Marketplace to see how different wattage panels will affect your unique system

How much energy does a solar panel produce?

For the sake of 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.

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. 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 the total wattage of your solar panels plays a significant part in the overall cost of your solar system.

What can you power with a single solar panel?

In the example above, the solar panel is producing 1.5 kWh per day, which ends up being 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.

Why does solar panel output matter? How to calculate panel wattage

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 total power output of the solar panels in the 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 represents the amount of force of the electricity and amperes (amps) refers to the aggregate amount of energy used. The financial savings you derive from the solar system is a result of the electric energy that it generates over time (expressed in kilowatt-hours).

Size vs. quantity: typical solar panel ratings and capacity

Power output on its own is not a complete indicator of a panel’s quality and performance characteristics. For some panels, their 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 every year in Los Angeles because of the amount of sun each location gets each year.

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.

How many watts of energy does a solar panel produce?

The graphic below presents a view of power output from many of the manufacturers who supply 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 company has a significant range. The table below lists the minimum, maximum, and average power outputs of the solar panels within each manufacturer’s portfolio.

Electricity output (in Watts) of solar panel manufacturers

Solar Panel Manufacturer
Boviet Solar320340330
Canadian Solar225410323
ET Solar255370306
Green Brilliance230300266
JA Solar260395324
LG Solar315415368
Merlin Solar320350335
Mission Solar Energy300390334
Phono Solar260350294
Q CELLS285430355
REC Group275380337
Renogy Solar250300268
RGS Energy556058
Solartech Universal310325318
Trina Solar260395327

What solar panels produce the most electricity?

Solar panels usually range in wattage output from around 250 watts to 400 watts, but some panels exceed the 400 watt mark. The solar panel with the highest watt is the SunPower E-Series, a commercial solar panel line. The top panel in the E-Series comes out at a whopping 435 watts. When just looking at residential solar panels, the top wattage panel available is the SunPower A-Series AC Module – the top panel in the A-Series line boasts a wattage of 425 watts.

Three Tips for Solar Shoppers

1. Homeowners who get multiple quotes save 10% or more

As with any big ticket purchase, shopping for a solar panel installation takes a lot of research and consideration, including a thorough review of the companies in your area. A recent report by the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) recommended that consumers compare as many solar options as possible to avoid paying inflated prices offered by the large installers in the solar industry.

To find the smaller contractors that typically offer lower prices, you’ll need to use an installer network like EnergySage. You can receive free quotes from vetted installers local to you when you register your property on our Solar Marketplace – homeowners who get 3 or more quotes can expect to save $5,000 to $10,000 on their solar panel installation.

2. The biggest installers typically don’t offer the best price

The bigger isn’t always better mantra is one of the main reasons we strongly encourage homeowners to consider all of their solar options, not just the brands large enough to pay for the most advertising. A recent report by the U.S. government found that large installers are $2,000 to $5,000 more expensive than small solar companies. If you have offers from some of the big installers in solar, make sure you compare those bids with quotes from local installers to ensure you don’t overpay for solar.

3. Comparing all your equipment options is just as important

National-scale installers don’t just offer higher prices – they also tend to have fewer solar equipment options, which can have a significant impact on your system’s electricity production. By collecting a diverse array of solar bids, you can compare costs and savings based on the different equipment packages available to you.

There are multiple variables to consider when seeking out the best solar panels on the market. While certain panels will have higher efficiency ratings than others, investing in top-of-the-line solar equipment doesn’t always result in higher savings. The only way to find the “sweet spot” for your property is to evaluate quotes with varying equipment and financing offers.

For any homeowner in the early stage of shopping for solar that would just like a ballpark estimate for an installation, try our Solar Calculator that offers upfront cost and long-term savings estimates based on your location and roof type. For those looking to get quotes from local contractors today, check out our quote comparison platform.

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46 thoughts on “How much energy does a solar panel actually produce? Electricity output explained


    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.

  2. 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?

  3. Steve McGugan

    Michael Moore has just released a movie that is very detrimental to solar panel energy ! If panels last for 25 / 30 years is the power generated worthy of the energy needed to build them ? In the documentary 2040 there present systems that are networked to smaller areas – streets – rather than national grids. Is this better in the long run ?

  4. Engr Akpanoko Joshua

    I have installed 300w *8 to power 2kw load,after installation I tested the out put it was OK after two months the voitage Drop to 1.5kw without additional load in the premises what will be the cause

  5. Patrick Conaty

    I have solar panels on my garage and they don’t produce anything. I paid 10,000 euros to get 6 panels installed on the roof and im still paying the esb. I think the neighbour has rigged his power box to my solar panels. The dog chewed on a lead in the garden which I thought was for the outside tap but the poor lad heeled over and never got back up. He’s buried now with the cat.


  6. David Larbalestier

    I recently installed 17 x 340 W LG panels (5.78 kW) with Enphase inverters. After 2 months we can see that it is producing 500-500 kWhr/month. So far, so gaod. But we notice that the peak hourly energy production rate flatlines at 4 kWhr/hr, meaning that the efficiency is much less than we expected, only 70%. This is not an issue of poor solar access, since the panels are in full sun without obstruction for many hours a day. In the nearly three months we have had the system, we can see the 15 minute power flatlining at 4 kW for more than 20 of the days it has been working. Is solar really so inefficient or is there something I am missing here?

  7. R.K.Hegde

    I got installed 3kw (375x8Nos) solar panals on my roof in Sept 2019.Till date it has not given me the rated out put.Max out put reached is 2250 wats.Kindly adcice


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