If you’re thinking about installing solar panels, you probably have numerous questions about the process. One of the biggest concerns is how much electrical power solar panels can produce and whether it will be enough for your home.

But the answer to “how many watts in a solar panel?” question isn’t universal and depends on several factors.

If you’re interested in learning more about the electrical power of solar panels, you’ve come to the right place. In this article, we’ll discuss what factors contribute to the efficiency and how to calculate the number of solar panels you need.

Power Output of Solar Panels

The power output of each solar panel is expressed in watts. Typically, residential solar panels produce between 200 and 400 watts per hour. The higher the wattage, the more efficient the solar panel. The manufacturer tests the solar panels before putting them on the market and usually states the wattage in the product’s name.

But keep in mind that the manufacturer states the wattage under ideal weather and temperature conditions. In reality, such conditions don’t happen often and can largely impact the actual power output.

What Factors Can Affect the Power Output of Solar Panels?

Many factors influence the amount of electricity solar panels can generate.


Solar panel efficiency is how well they turn sunlight into electricity. Most panels are only 15%-20% efficient. High-efficiency panels exceed 20%, but they are often much more expensive.

Although high-efficiency panels cost more money, they usually take up less space.

Efficiency depends on the material used for the solar panels. Monocrystalline panels are more efficient due to the high-grade silicon used in the production, but they are more expensive. Polycrystalline panels aren’t as efficient, but they are more affordable.

Number of Cells

Solar panels are comprised of photovoltaic cells joined together. These cells turn sunlight into power you use for your home. Each panel has a certain number of cells ranging from 36 to 144, though the two most popular options are 60 and 72-cell solar panels.

60-cell panels are typically used for houses. They are smaller in size and have average dimensions of 5.4 by 3.25 feet.

72-cells are used for commercial purposes, and their dimensions are 6.5 by 3.25 feet. The power output is between 320 and 400 watts. You may wonder why they can’t be used for houses, and the answer lies in the size. Most houses have smaller roofs, and it’s impossible to fit 72-cell panels.


Your roof plays a vital role in how much power solar panels can produce. Let’s review the essential characteristics.


Your solar panel will produce the most energy if it’s faced towards the south. Depending on your roof structure, panels can also receive a decent amount of sunlight if positioned east or west. If you have enough space, you can install extra panels to make up for the orientation.


To achieve the best results, solar panels need to be tilted at a certain angle. The best tilt angle depends on your location and orientation, but it should be between 10-60 degrees.

If your roof has a different tilt angle, don’t worry. Solar panels can still perform well and produce enough power, but you may need a few additional panels.


If your solar panels are installed in a shaded area, they will produce drastically less power. It’s best to install them in places that get direct sunlight throughout the whole day.


Weather conditions aren’t ideal anywhere, and you may wonder whether some locations are more suitable for installing solar panels. The efficiency of solar panels is definitely affected by the weather. A clear, sunny day is ideal for getting the most out of solar panels.

People often think solar panels work best in states with high average temperatures, which isn’t the case. Their efficiency drops as the temperature rises, making them much more efficient in cold weather. Still, solar panels produce more energy during summer. Be aware that this doesn’t have anything to do with temperatures but with sunlight. During summer, the days are longer, giving the solar panels more time to absorb power.

Another misconception is that solar panels don’t work well in cloudy areas. Depending on the cloud thickness and the solar panel efficiency, the electricity production will drop, but only by about 10%-20%. This confirms that solar panel systems can still produce enough power even when it’s cloudy.

Time of the Year

As mentioned, solar panels produce more energy during the summer months because the days last longer and there’s more sunlight. They also work better in areas with lower temperatures.


If the solar panels are dirty, it will compromise their effectiveness. It’s recommended to clean them regularly with a damp cloth or a brush. Don’t rely on rain cleaning the debris and dirt.


Like most other products, solar panels become less efficient over time, and this process is called degradation. As they age, they will produce less electricity, and your contractor typically accounts for this. When you have solar panels installed, you’ll receive a performance warranty that confirms the efficiency won’t drop below a certain percentage.


Solar panels produce direct current (DC) energy. Inverters convert this energy to alternating current (AC), which is used in households. These inverters can often cause minor losses of energy.

How Many Watts in a Solar Panel

How Can I Calculate How Much Power a Solar Panel Produces in One Day?

The easiest way to get a rough estimation of how much power you get from a solar panel each day takes into account its wattage and the amount of sunlight for that day.

For example, if you have a 280-watt solar panel and five hours of sunshine a day, it will generate 1,400 watt-hours (280 x 5), which is 1.4 kilowatt-hours (kWh) per day. If you want to get a monthly estimate, multiply this number by 30.

Most homes install several solar panels, depending on the roof size and the overall household needs. Multiple panels joined together are called solar panel systems. To calculate the power output of the entire system, multiply the wattage of each one by the number of panels.

How Much Solar Power Do I Need?

First of all, you need to decide whether you want to power your entire house with solar energy or just a portion of it. Then, you need to determine how much power you use per month. For this, take your electricity bills and look for “kWh used.” If you don’t see this, keep track of your meter readings to determine monthly usage.

Electricity bills typically express monthly electricity usage. To calculate daily use, divide that number by 30. For example, if you spend 570 kWh per month, that’s 19 kWh per day. Then, divide the number by 24 to get hourly energy consumption, 0.80 kWh in this example. This number represents how much solar energy you’ll need per day to power the entire house.

If you want to cover the whole house, you’ll need 20-30 250-watt solar panels on average. You may wonder what happens if you don’t have enough space on your roof for that amount of panels. In that case, you can opt for ground-mounted panels, more efficient and expensive roof panels, or do nothing. Although the solar panels may not cover 100% of your electricity bills, they will still save you a lot of money.

How Can I Be Sure What Solar Panels I Need?

As you can see, calculating how many solar panels you need isn’t just about their wattage. Many factors such as efficiency, size, roof position, and location can affect the number.

If you’ve done the math, you probably have a rough estimation of what solar panel system you need. But if it seems too complicated, you don’t have to worry about it. Solar contractors will give you an accurate estimate of your requirements.

As soon as you contact a solar company, they will come to your house to inspect your roof, calculate its size, and make the necessary assessments. You’ll receive a detailed proposal on how many panels you need to power the entire house or only a portion of it, depending on your preferences.

Professionals will consider all the above factors to determine what solar panels would be the best option for your house.

To ensure you’re getting the most for your money, do your research before hiring a company. Check online reviews and ensure they have the necessary licenses. Additionally, ask several contractors for a quote. That way, you can choose the best offer.

Welcome to the Sunny Side

Different solar panels can produce different amounts of energy, making wattage one of the essential factors to consider. As mentioned, most solar panels produce between 200 and 400 watts. But keep in mind that manufacturers measure wattage in ideal conditions, which doesn’t mean you’ll get the same results.

We hope this article provided answers to the “how many watts in a solar panel” question. Additionally, we hope you’ve learned more about what other factors to keep in mind and that you’re now one step closer to solar.

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