One of the most important features of a solar panel is how much energy it can produce. Prospective solar panel owners usually have a goal for how much energy they want to produce. Maybe it is 100% of their household needs, or even just 50%, but in any case, there are several factors that will influence the energy production capabilities of a solar panel.
How Much Energy Does One Solar Panel Output?
To get an accurate picture of how much energy a solar panel can produce, you must first consider what type of panel technology is being used. If you were to find a solar provider and look through the products that they offer, you would probably find 2 types of solar panels: monocrystalline and polycrystalline. Here are some features of each technology.
- Higher efficiency
- More expensive
- Better performance in high temperatures and shady conditions
- Lower efficiency
- Less expensive
- Less efficient at higher temperatures
Check this video to find out the difference between Mono crystalline and Poly crystalline panels.
As you can see, each type of panel has its pros and cons. Polycrystalline, however, is a newer technology and will become more efficient over time, but if you were looking to generate the most power in the smallest amount of space, monocrystalline would be the way to go. The panel technology is the first factor in the panel’s production abilities.
Key Solar Panel Terms: kW, kWh, DC, and AC
To fully understand the numbers, we need to go over some basic units.
- kW – Kilowatt. This is a measure of electrical power, which is equal to 1000 watts. The electrical energy that is generated by a solar panel or a solar system can be expressed as watts or kilowatts.
- kWh – A measure of electrical energy that is equal to the consumption of 1000 watts for 1 hour. The kWh is used as a billing unit for the energy consumed by individuals. One kilowatt-hour equates to 3.6 megajoules.
- DC – Direct current power. This is the form of the power that gets initially generated from the panel.
- AC – Alternating current power. DC gets converted into AC so that it can be used efficiently by consumers throughout their house.
The amount of electricity a solar panel produces depends on three important factors: the size of the panel, the efficiency of the solar cells inside, and the amount of sunlight the panel gets.
Average Solar Panel Size:
When we say, “solar panel,” what we are talking about is a typical 60-cell silicon photovoltaic panel for residential use. These days, most home solar panels are about 65 inches high by 39 inches wide, or 5 and a half feet tall and a little more than 3 feet wide:
If you look closely at the solar panel in the image above, you will notice 60 little squares aligned in 6 columns of 10 cells each. These squares are individual solar “cells,” which are linked together by wires. The cells are where electricity is made, and the wires carry the electricity to a junction box where the panel is hooked into a larger array.
Manufacturers also make solar panels with 72 cells, which are aligned in 6 columns of 12 cells each. 72-cell solar panels are also 39 inches wide, but average about 78 inches long. These larger panels are mostly used for commercial and industrial solar installations but are increasingly popular on homes.
Why does solar panel size matter?
The more solar cells working in tandem, the more power they will create. That is why the size of the panel matters if you are trying to calculate how much electricity a panel makes.
Solar panels have been about this size for decades, but modern panels make more electricity than in the past. That is because panel manufacturers have found ways to improve cell efficiency over time.
Since the first solar panels were created in 1954, the cells have become more efficient and changed shape from round to square, which means the energy-generating portion of the panel takes up a larger portion of the total surface area. These changes have caused a big increase in solar panel power output.
How efficient are solar panels?
Solar efficiency relates to the amount of available energy from the sun that gets converted into electricity.
Back in the 1950s, the first solar cells could take 6% of the energy from the sun and converting it into electricity.
If they were configured to be the same array of 60 cells you see in the image above, that would have created a current of about 20 watts electricity, about a third of what would be needed to light up a 60 watt incandescent bulb.
In 2012, solar cells could convert 15% of the energy hitting them from the sun into power. As of 2020, the efficiency of the most advanced solar cells is closer to 25%, while average solar cells for residential use are around 19% efficient.
If you combine the efficiency of the cells with the size of the panel, you get a number called the “power rating.” In the solar industry, we say “that panel is rated to produce X watts.”
How many solar panels are needed to power an average house?
Sizing a solar panel system to your home’s electric usage can be done by taking look at your energy bills over a year.
Most utility companies provide information about your last few months of usage on your bill, but you can probably get more on their website. A few lucky customers get a year and a half.
We will spare you the trouble of averaging that column and tell you that this house uses about 2,200 kWh per month. That is quite a bit higher than the national average, which means the homeowner could really be helped by solar power!
Typically, homeowners in the United States use about 900 kWh a month on average. So, take 900 kWh and divide by the amount of kWh one solar panel produces over the course of a month (30kWh), and you get a 30-panel installation. 30 panels x 250 watts per panel equals a 7,500-watt system (7.5kW).
Again though, these are just rough estimates. It is best to connect with us so we can appropriately size a system and help take advantage of all the local incentives to get it done right and as affordably as possible.
The wrong azimuth angle could reduce the energy output of a solar PV array down by 35%. Here is a table to better explain the azimuth angle effect.
Azimuth is the array’s east-west orientation in degrees. In most of the solar PV energy calculator tools, an azimuth value of zero is facing the equator in both northern and southern hemispheres. Positive 90 degrees is facing due west; negative 90 degrees is facing due east. The compass angle shows 180 for south, 90 for east and 270 for west.
To sum it up, a solar panel, by itself, typically should be able to cover about 1/20th of your household energy needs. Therefore, most solar arrays include 10-20 panels so that they can cover most of their needs. Obviously, this can vary widely depending on many variables, particularly how much electricity you use and how much roof space you have available. Other considerations include the type of panel technology, efficiency, location, angle, climate, and more.
At the end of the day, the main point to be made is that there has not been a better time in history to adopt solar. Not only can you easily generate enough energy to cover all your energy needs, but solar panels are now cheaper and more efficient than ever.
Written By: Laila El Azhary