How much energy does solar panels produce?

how much power do solar panels produce

The advent of this century has brought with it an ever-increasing consumption of fossil fuels for energy.

We have reached a point where it seems unthinkable to run our daily lives without established energy sources. Unfortunately, our generation uses natural oil, petroleum, and coal at a dangerously accelerated pace.

And, soon, our dependence on non-renewable energy will backfire, leaving us scavenging for sustainable energy sources like hydroelectric power, solar energy, and geothermal energy.

In several countries, the initiative to switch to renewable energy solutions is already underway. On a personal level, individuals may not be able to use wind, hydro or geothermal energy. Practically speaking, investing in residential solar panels is the only viable option for the average Joe.

A few years ago, the California Energy Commission approved solar panels on all new single-family homes. This initiative is said to reduce electricity bills considerably. But exactly how much energy does solar panels produce? Can your home appliances depend on the electricity provided by solar panels?

Let’s find out!

Types Of Solar Panels

The major contenders in the solar power industry are monocrystalline, polycrystalline, and thin-film solar panels. They differ in build, appearance, cost, installation, and performance. And as a homeowner, one type of solar panel system might appeal to you more than another.

Monocrystalline Solar Panels

Monocrystalline solar panels are made of silicon wafer cells. The silicone is arranged in rows to form rectangles and topped with a glass sheet. This type of solar panel is made from a single silicon crystal; hence it is called monocrystalline.

Identifying this solar panel is easy – just look for the black celled solar system, and it most likely will be the monocrystalline type. When it comes to efficiency, there isn’t a solar panel system that can beat this option. Its efficiency rate can reach 20 %, the highest of any solar panel, and it also comes in higher wattage options exceeding 300 to 400 watts.

This solar panel can produce more energy while occupying less space and resisting heat better. However, it is the most expensive home solar panel on the market.

Polycrystalline Solar Panels

Polycrystalline solar panels are also made of silicone, but instead of a single pure crystal of silicon, they are composed of fragmented crystals joined together. In appearance, these solar panels seem to have slightly bluish speckles and are not as dark as monocrystalline options.

Due to their make, the overall efficiency is also lower at around 15 %. They also have a shorter life span and might get affected by high temperatures to a greater degree. On the bright side, with a simpler manufacturing process, this solar panel system is much more cost-effective.

Thin-Film Solar Cells

The last type, thin-film solar panels, is created using different materials, and the most common one is cadmium telluride. Instead of joining crystals together, this method uses material layers between transparent conducting layers for collecting sunlight. Another combination of material, namely Copper Indium Gallium Selenide or CIGS, is placed between two conductive layers like glass or plastic.

Compared to others, this solar panel is much thinner and lighter since they do not have thick frames. Thin-film solar panels are easier to produce on a larger scale; thus, they are cheaper than traditional models. However, they take up a lot of space, so installing them in residential buildings is not feasible.

How Does A Home Solar System Work?

Essentially, a solar system for a home is made of silicone. When the sunlight hits the solar panels, the photons are collected and converted to direct current or even electricity. However, DC (direct current) is not readily used for charging home appliances since they run on AC (alternating current).

This is why an inverter is required to create AC electricity out of DC. And the photons collected on the solar panels are sent to the central inverter in a synergistic fashion. However, there are a few solar system models designed to work with each solar panel as a separate entity.

Factors Affecting Solar Energy Output

The amount of energy produced by a solar panel depends on three main factors

  • Panel Size
  • Solar cell efficiency
  • Amount of direct sunlight

Panel Size

Most residential solar panels contain 60 silicon cells, with the panels measuring 65 inches in height and 39 inches in width. Taking a close look at any solar panel, you’ll find the entire structure is made of individual cells connected by wires.

But does the panel size matter at all? Yes, the size determines how much electricity is produced by the setup. While most solar panels have not changed, commercial spaces use a larger solar panel containing 72 cells. The width remains the same, but the height measures around 78 inches.

Needless to say, these solar panels have more solar cells per panel and produce high capacity power output and, thus generating more electricity.

Solar Cell Efficiency

Also, over the years, the standard power output has increased the overall solar panel efficiency, but the size is pretty much the same. In the mid-50s, when solar energy emerged as an alternative energy source, the solar panel wattage conversion was merely 6%. Meaning only 6% of the sunrays received by the panel were utilized for electricity.

As we have progressed, modern solar panel wattage can now convert 15% to 25% of sunlight into energy which is a vast improvement. One thing to understand is “power output ratings” are derived from a combination of the size of the panel and the cell efficiency. So, the wattage system is based on these two factors.

Amount Of Direct Sunlight

How much sunlight the panel receives is one of the most important factors deciding the amount of energy the solar panel produces. More hours of direct sunlight will automatically mean more electricity generated.

Speaking of which, sunlight is not the same in all places, and the weather trends at your location will affect the power output. If your area receives too much rain, clouds, and a few hours of light, the panels cannot produce to the best of their efficiency.

Solar panel system capacity is conditional and seasonal changes are another example of environmental reliance. It is observed that power production peaks during summers when there is more direct sunlight and reaches its lowest during winter.

How Much Energy Can A Solar Panel Produce?

The first thing to consider is the STC or PTC rating of the solar panel in question. STC or Standard Test Conditions will give you an idea of the panel’s power when it functions in total capacity. The makers test the panel under peak sunlight to check its power and arrive at a number based on how much energy it produces.

For example, if a solar panel can produce 175 watts of energy in one hour, it can have an STC rating of 175. If you know the STC rating of one panel, multiply the number by the number of panels you’ve got in total. This will give you an approximate of how much electricity/ power output the system can provide.

How To Calculate Your Solar Panel Output

Let’s say the solar panel is installed in a sunny area with plenty of sunlight and six hours of direct sun rays. A rating of 175 is pretty low, so let’s assume you have a premium solar panel with a 300-watt solar panel efficiency. If you multiply 300 (watts) by 6 (direct sunlight hours), you get 1800 watts or 1.8 kilowatt-hours (kWh).

So, with 1.8 kilowatt-hours per day, you would expect a yearly energy output of 650 kilowatt-hours. Considering that every day will not be sunny, let’s consider the environmental factors and average the output to 1 kWh per day. This changes the average actual yearly production drastically, with around 360 kilowatt-hours (kWh) per year.

To get a good idea of how much electricity your solar set up can produce, you need to know two things. The first is the wattage of the solar panel, and the second thing is the peak sun hours in your location. Then multiply the panel wattage with peak sun hours.

Let’s consider this –

  • Area – New York
  • Wattage – Solar panel with 370 watts
  • Peak Sun hours – 3.5

Thus, 370 watts multiplied by 3.5 peak sun hours gives 1295 watt-hours. A homeowner with this setup would get 1295 watt-hours of electricity per day. If you divide this by 1000, you get 1.3 kWh per day. So, this system, based on this particular location, will provide 1.3 kWh per day or 39 kWh per month ( 1.3 kWh x 30 days) or  475 kWh per year (1.3 kWh x 365 days).

With this simple calculation, you can get a rough estimate of how much power your setup can provide for the month or year.

Factors That Impact Solar Panel Overall Efficiency

Panel Direction

A commercial solar panel line may not have the space restrictions of a home solar panel. Most home solar panels may have a few directions and angle limitations. Energy collected on the roof space may get position if the direction isn’t right.

Usually, a south-facing roof generates more energy, while those facing west or east with less sunlight will have lower solar panel performance strength.

Roof Space And Panel Angle

Additionally, better angles lead to improved sunlight/photon collection, which results in more power production. Placing the panel at the correct tilt for your location is necessary to increase solar panel output.

Usually, solar panels produce the most energy when facing south. But they also need to be installed at the appropriate angle that matches the approximate latitude of that area. For example, a 45 to 40-degree tilt works best for the Northern USA, while a 30 to 25-degree tilt will do for the Southern USA.


Sunlight received by a location varies due to environmental factors like pollution and dust. Debris and dirt collecting on the panels can hinder solar production and reduce panel efficiency.

If the panels are clouded with sand, rain, or snow, the cell’s ability to harvest sunlight is seriously affected. Still, you can avoid it by conducting regular or annual cleanups to keep the solar panels’ efficiency intact.


This may seem comical, but the energy a solar panel generates reduces if the temperature is high. It’s strange but true – Average power outputs see a drop, and efficiency is reduced when the area temperature is too high.

This is because of how the semiconductor material reacts to hot temperatures. And, as the temperature drops, the voltage between the cells drops too, thus increasing the solar cell efficiency in converting photons to energy.


As with any other device, solar panels generate less energy as they age. It is assumed that performance drops by 0.5% per year of usage.

How Much Solar Power Does An Average Home Need?

Like each home uses a different amount of electricity, it requires a unique solar panel output to meet its requirements. After all, the devices present in the household and their use will change the daily energy requirement.

If you want to install solar panels on your rooftop, check the monthly bills to check how much energy is generally used. Switching to solar energy will require you to figure out the daily energy consumption in kWh instead of monthly. All you need to do is divide the monthly consumption by 30 to get an average of daily power usage.

Now that you know how much electricity the home needs daily, it will become easier to calculate how reliant you wish to be on solar panels. Are you looking for 100% of your energy to come from solar energy? At first, it might not be practical to make such a drastic switch.

Aiming for a 50 to 70% offset is more realistic considering the weather conditions, shade, and other factors previously discussed.

How Many Solar Panels Should You Install?

Again, it depends. Smaller families could make do with one solar panel, while others may not find two solar panels enough. Also, you can only fit in as much as your roof offers. Larger roofs have the luxury of holding many cheaper panels, thus reducing your purchasing cost.

A typical house in the USA can use up to 900 kWh per month. If you divide this by 30 (for 30 days of the month), you get daily energy costs of 30 kWh. If you choose a 60-panel installation, with average watts of 250 gives you a 15,000- watt system. This translates to roughly 15 kW produced per day to cover half your electricity usage.

This is just a hypothetical example, so your actual calculations will differ. As we mentioned earlier, location can drastically change the solar panel output even if you select a standard solar panel. In the hot states of New Mexico and Arizona, one kW solar setup can produce 5 kWh of energy daily.

While in Minnesota and Washington state, the same setup will give you only 3 kWh of energy. Anyway, the best option for you would be one that suits your roof space and budget, meeting a portion of the monthly electric requirements.

Final Words

In summation, power output ratings ranging from 250 to 300 kWh do not guarantee optimum energy production. Yes, a high power output rating will surely provide much more energy, but you also have to consider factors like cost, climate, and installation method.

Ultimately, switching to alternative forms of energy will become the norm in the near future. And for households, investing in rooftop or home solar panels is the easiest way to hop on this trend. If used wisely, it can replace the need for traditional energy but, it can surely reduce a chunk of your monthly utility bills.

Need professional help when it comes to solar panel installation, maintenance or repair? Look for the nearest solar installer in your neighborhood.

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