How Much Power (Watts) does a Solar Panel Produce?

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We use various kinds of solar-powered products every day, and we benefit from them a lot. But how much electricity does a solar panel generate?

The key point is to select a model with a suitable solar panel. And power output of a solar panel is one of the most significant matters you need to consider when choosing or comparing solar panels.

You may get confused when seeing the given numbers of 250 watts, 300-watt, and so on. Generally, they are referring to the wattage, power output, and capacity of a solar panel.

Key points about solar panel output

  • Standardized residential solar panels on the market are quoted to generate averagely between 250 and 400 watts an hour.
  • Typical domestic solar panel systems are rated to produce power ranging from 1 KW to 4 KW.
  • The actual output of a solar panel depends on many factors, such as its size, capacity, location, orientations, and weather conditions.
  • You can compare different output quotes of a solar panel and see how solar panels with different capacities will influence your particular solar system. You can search on the EnergySage to find more specific information.

How to calculate solar panel output for your home?

Each of you has a particular solar system, and every solar panel is unique. So it is difficult to put it how much electricity your solar panel system will produce. But you can have an approximate idea by searching the Solar Calculator Center of the Alternative Technology.

There is some common criterion for you to use when measuring the rough power output of your solar panel system.

Solar panel output per day

It is usually measured in kilowatt-hours (kWh). To estimate the potential electricity that your solar panels would generate per day, you can use the following formula:

  • Size of one solar panel (in square meters) x 1,000
  • That figure x Efficiency of one solar panel (percentage as a decimal)
  • That figure x Number of sun hours in your area each day
  • That figure was divide by 1,000

Plus, you can use this calculator to figure out the sun hours in your areas. And the efficiency of the solar panel is given by the product maker. But you should pay attention to that the sun hours per day could be largely variable in different seasons and locations.

Solar panel output per month

Based on the above-mentioned formula, you can easily get the daily data. So to get the monthly power output, you simply calculate the daily figure then multiply it by 30:

  • Daily figure x 30

Solar panel output per square meter

The most common domestic solar panel system is 4 kW. And it has 16 panels, each of which is about 1.6 square meters (m2) in size. They are rated to generate approximately 265 watts (W) of power (in ideal conditions).

To calculate the output per square meter, you can use the following formula:

  • Number of panels x Capacity of the solar panel system
  • Capacity ÷ Total size of a system (number of panels x size of one panel)

Also, you have about two different ways to calculate the power production that you might get from your solar panels at home. They are mainly related to how much power you need and how many square meters of roof space they will account for.

You have two options: easy and rough way; accurate and complex way.

  • Easy way

The easy way is to use solar panel calculators. And some online solar panel calculators are free of charge. They are previously programmed by all the required information and can work out data automatically.

You can just enter your zip code, power bill, and utility provider, then the calculator will automatically work out all the data you need. Moreover, it can also estimate the cost of solar, based on solar company pricing in your district.

  • Complex way

The complex way is more effort-consuming and accurate, comparing to the easy way. What you need to do is seek the meteorological data of your area, estimate the direction, and slope of your roof.

Besides, to know exactly how much solar power you need, you have to check your power usage patterns and the usable net metering scheme from your utility.

How much energy does a solar panel produce?

As you have known, the solar production of a solar panel can be affected by many factors, including location, shading, sun hours, and weather conditions. So we need to put it in an ideal situation.

For instance, if your solar panel system can get 6-hour of direct sunlight each day in a sunny area like California, you can calculate your solar panel output using this formula:

6 hours x 300 watts (an example wattage of a premium solar panel) = 1,800 watts-hours, or roughly 1.8 kilowatt-hours (KW-h). Therefore, the total output for each solar panel in your array will generate about 600-650 kWh of energy a year.

A solar panel is rated by the amount of direct current (DC) power it generates under standard test conditions. We usually express solar panel output in units of watts (W). And pricing in solar is usually measured in dollars per watt ($/W), so the total bill of your solar system is determined by the final wattage of your solar panels.

Besides, how many watts a solar panel can produce is represented in a theoretical power production, which means it is a figure depending on the ideal sunlight and temperature conditions.

Average household solar panels on today’s market offer power output ratings expanding from 250 to 400 watts, you can choose from freely according to your power requirement and anticipated budget.

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

This is a seemingly simple question, but it is not. Since your locations can heavily influence the solar output, you need to take the weather conditions, direct sun hours, and something else into consideration when thinking of this question.

Also, different houses have unique solar panel systems for distinctive purposes. So you may need different numbers of solar panels. But to figure out the typical panel numbers, you can check out in an article the average number of solar panels required to power the average home in each state.

How effective do solar panels work?

You might think that a solar panel with high efficiency will produce more power, but efficiency is not the only factor that plays a role in its effective working. Multiple factors are affecting how much electricity your solar panels will produce:

  • Efficiency

Efficiency refers to how much sunlight a solar panel can convert into electricity. To be clear, owing to the variable and inconsistent working conditions, the efficiency can never be 100%, even can be less than 50%.

As we know, most residential solar panels have an efficiency of about 20%. There are also solar panels with a relatively high efficiency of 40% or more in the market, but they can be very expensive. The good side of the panel with a big-budget is that it can use less roof space.

  • Capacity

Capacity is also called ‘rated output’, which stands for the maximum number of electricity that the solar system can generate under ideal conditions. If there are enough direct sunshine and peak hours, the capacity is large.

Usually, the typical amount can be 1,000 watts of sunlight per square meter of the panel. As we have mentioned before, average domestic solar panels hold a capacity ranging from 1,000 watts to 4,000 watts.

  • Location

Location is another factor that can have a big influence on power production. Different areas have different sunlight amounts. And the physical geography of a particular location can be very unique. It affects the sun hours too.

Your location would determine how much sunlight the solar panel will receive and how many peak hours there are every day. Even a slight difference can lead to distinctive power output.

  • Direction

Direction means the specific orientation of your roof. Houses are built in different places, and each house may have roofs with different shapes and faces. So when you place your solar panel on the roof, it can be influenced by the roof directions.

Usually, south-facing roofs receive the most sunlight, while solar panels working on roofs that face east or west would receive less sunlight and produce less power.

  • Angle

Check your roof angles. They can be variable. And angles may affect the direct sunlight hours. A roof that has a tilted angle of about 30 degrees is reported to offer the best overall performance.


To have the best user experience, you need to get a clear understanding of how much power a solar panel could produce. When comparing different solar panels in the market, you should consider all the previously discussed questions and make a wise choice.

Working out all needed data is also significant to make the best use of your solar panel system. Check out your devices that need to be powered by solar energy and calculate how much power your house needs.

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