You may know that solar panels are useful, and maybe even how many you need to cut down on some of your electricity bills. However, you may not understand how solar panel output works, why you need as many panels as you do, or how to determine how solar panel wattage will change your electricity usage.
While the whole formula is pretty complicated and may be hard for even installers to explain, there are some basic things about solar panel output you can understand so you learn the key takeaways, and get a better idea of what factor or factors influence your solar panels. This may make it easier to determine your needed system size and the pricing behind it.
What You Need To Know About Solar Panel Output
Solar panel output is the amount of energy, which is recorded as DC [direct current] power, that you get from your solar panel. There are two levels of your solar panel output, which are the amount of energy that your solar panels could theoretically produce, and the actual output.
While they can sometimes line up, they rarely do so because of multiple external factors. So, when you are determining how large of a solar system you need, keep in mind that going a little higher is never a bad thing as it is rare that you will get full power.
Even when you do, even the best solar panel manufacturers aren’t able to make solar panel models that can be 100% efficient, which is why they don’t have a super high power output rating. But rooftop solar can still help to reduce your carbon footprint and reduce your dependency on the power grid while still meeting your energy needs, especially if you get battery storage.
Whether you want a power rating high enough to meet every home need or just enough to help the environment and power a few appliances or small side buildings on your property, you will find that understanding power output makes it very easy.
Output vs Cost of Solar Panels
For the most part, solar panels are the cheapest part of any solar system. Generally, the average cost of solar panels is calculated per watt. There are various types of solar panels that have different costs, but generally, you can expect a solar panel to cost between $1 to $2 per watt.
However, that is before installation. If you are hiring a professional to work on your system, the price will increase. Generally, installation is almost the same cost as the system parts themselves, if not a little higher, depending on your home.
This means that, for the most part, you can expect your installed solar panels to cost between $2 and $5 per watt. On average, this means that, for a 6kW solar panel system, you can expect to pay between $5,500 and $25,000.
How the Product Changes the Output of Solar Panels
Unfortunately, not all solar systems work the same. Even if you look at the same physical size of panels that are the same kind, the output changes. Usually, they will be similar, but there may be a few watts of difference.
Additionally, some solar panel companies offer different sizes. Some can go below 100 watts, while others tend to stay around 200 or even 300. Some solar panel companies may also offer larger solar panels than others, with some going upwards of 450 watts.
While these larger solar panels often cost more, they are better options if you need a lot of solar because you have to buy less, which reduces your installation cost, and saves space on your roof or wherever you are installing the system.
You can mix and match panels to get the perfect amount you need without spending too much on work.
For this reason, it is a good idea to look at a couple of companies to get an idea of what size solar panel you want, both physically and from the output. You generally want to use panels all from the same company for the best results and not mix-and-match brands too much, so try to find a company that works best for you. Most companies have quite a large range, so you usually have plenty of options.
What Is the Best Way To Calculate the Output of Your Solar Panels?
1. Calculating Daily Output
The wattage that is given to you when you buy a solar panel is based on the maximum amount of solar output your solar panel can get at one time. However, you can’t multiply that number times 24 to get your daily output.
This is because there will be quite a few hours when solar panels don’t get power, such as at night. There will also be times when your solar panels aren’t getting full power, such as when it is cloudy or when the solar panels aren’t at their peak angle.
There are plenty of calculators online to help you out, but in general, you need to calculate the average number of solar hours per day times the wattage of your solar system. This will give you a base estimate of the maximum potential solar power energy you can get in a day.
If you want to calculate it more specifically, focus on only the peak hours of sun, and not the total amount of sun, as the solar systems will be most efficient only during this time. You can also multiply it times 0.75 to be even more specific, as you will lose some power by transferring the output, and due to unfavorable weather.
2. Calculating Output by Square Footage
While this isn’t a perfect method, if you want an estimation of how much wattage you can get per square foot of space, you can calculate it. This is a great option if you want to be able to see if you have enough space on your roof to even give you the wattage you need.
Generally, you can estimate that solar panels will provide you with somewhere between 9 and 13 watts per square foot. As solar panels become more efficient, that number goes up, but right now, this is still the average.
So you multiply these numbers times the space available to get an idea of the range of solar energy output you may be able to get. If you want to be conservative, start with the lower number and use that as your base.
As an example, if you have 90 square feet of space, you will be able to get between 810 and 1,170 watts of power at one time.
3. Calculating Monthly Average Output
Calculating monthly average output starts with you calculating daily output. Then you simply take that number and multiply it by 30. This will give you an average monthly output.
It should be noted that these are just estimates. You will sometimes do better and sometimes worse, depending on the weather, the amount of sunlight available each day, and the angle of your panels. While this gives you an estimate, it isn’t perfect and there are a lot of external factors that can influence your solar panel’s ability.
What Can Change the Amount of Energy Your Solar Panels Are Outputting?
External Factors
There are quite a few external factors that influence the quality of solar panels. Some examples are temperature, shading, weather, and angles.
Solar panels don’t do well when it is particularly hot or cold. They can handle moderate temperatures, but their efficiency decreases when they are overheated.
This is hard to control because you need a lot of sunlight, which usually means they also tend to get warm, but in tropical locations, solar panels may lose more efficiency than other solar panels.
Shading also influences solar panels. Even just a little bit of shade can reduce efficiency dramatically. For this reason, you want to make sure your solar panels are somewhere they get full sun. Even if just a small corner is covered, you can see a large portion of your output is reduced.
The weather conditions that affect how much a solar panel produce is cloudy weather. Clouds and rain block the sun. While solar panels can still run during this time and get a little bit of power, it won’t be nearly as much as you would normally get.
Angles are one of the final external factors that influence the output of solar panels. Having your solar panels at the right angle allows them to have better power production and provide more electricity to homes.
Average Efficiency of Solar Panels
Solar panels are, unfortunately, not very efficient anyway. Depending on the style and kinds of cells you get, they are at most only 15% to 22% efficient. This means, even with perfect conditions, you are only going to get a solar panel that uses around 20% of the power that it is getting.
This means that to get the power you need, you have to invest a lot of savings and roof space in your solar panel system. While there are systems trying to improve performance all the time, right now, getting a higher power output from solar panels just isn’t possible.
Different Types of Solar Panels
There are multiple kinds of solar panels as well, that utilize different materials. There are four main types of panels that you are likely to see on the market for residences.
These are monocrystalline, polycrystalline, PERC, and thin-film. Each one has slightly different uses and benefits, but also different efficiency rates. Currently, it is PERC solar panels that are the most efficient.
This means you can save space with your solar system, but you do have to invest more money than you may expect as it is costly to build.
Often, the lower the cost, the less efficient it is. However, the cheaper ones may be more flexible for certain installations, and less wasteful.
Size and Quality of the Solar Panels
Solar panel systems come in all sorts of shapes and sizes. You can get ones that have high quality and a reputable manufacturer that is often slightly higher in efficiency. But that’s not all. Often, these solar cells can handle shade and external factors a bit better as well.
For example, a solar system that was created by reputable manufacturers is still usable when the sun goes away. They can produce a little more electricity for homeowners even without full sunpower.
This allows you to have a higher percentage of your solar power and to have a somewhat steady electricity output even when it isn’t fully sunny outside.
While the smaller brands may be cheaper, it isn’t worth the comparison as the products and technology are vastly different. If you want to have solar panels that last a long time and have even decent power output ratings, you need to look at a brand name.
Additionally, you can look at the size. Most often, the bigger the solar panel, the more silicon that is present, and the higher amount of output your home will get.
There are all sorts of different sizes, so you can just choose enough to cover your energy usage, or produce extra that you can store in your battery bank if you have one in your household.
Not only is the solar panel size important, but so is the size of your array. If you get multiple panels, you can install them in parallel or in series to get a more efficient system. While this doesn’t increase your solar panel efficiency, it can stabilize your power ratings and have your system work a bit better.
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Citations
- Brill, R. (2023, January 6). How Much Do Solar Panels Cost? Forbes Home. https://www.forbes.com/home-improvement/solar/cost-of-solar-panels/
- Aggarwal, V. (2022, December 14). What is the output of a solar panel? EnergySage Blog. https://news.energysage.com/what-is-the-power-output-of-a-solar-panel/
- Watt, T. G. (2021, December 22). How to Calculate Solar Panel Output? (+ Solar Output Calculator). The Green Watt. https://thegreenwatt.com/how-to-calculate-solar-panel-output/
FAQ
Why should I understand solar panel output?
By understanding what influences solar panel outlets, you understand why you need the system you need, and the impact certain factors have on your system. It also explains why certain panels are preferred over others.
Can size and quantity change the solar panel output?
The size and quantity of your solar panels can definitely change the output. While size changes don’t always mean output changes, generally, the bigger a solar panel is, or the more solar cells it has, the more power it produces. Again, since there are different types of solar panels, this isn’t always the case, but can be a decent rule of thumb.
However, the wattage of solar panels is almost always mentioned somewhere in the product, and the higher the number is the more power output you have, so you can look at that as well.
As for quantity, every panel you have adds to your solar panel output as long as you connect it back to your home. However, you can also run solar panels in series or in parallel.
Can a single solar panel be enough?
It depends on what you want to use it for. Due to efficiency issues, it isn’t possible right now for one solar panel to be able to provide enough power to run your whole house. For the most part, you won’t find a single solar panel that provides more than 500 watts or so.
If you just want to run one or two small things though, it may meet your needs. If you are unsure of how much power you need, look online for a calculator or table, which will break down the amount of energy from solar panels you may need for your home and your requirements.
Changing the way you wire the panels can change the voltage or the amps, so you can always talk to your solar panel installer about the way to wire them together based on what you need and the energy production you require.
