Calculate The Size Of Your Solar System
To figure out how to size your solar system, take your daily kWh energy requirement and divide it by your peak sun hours to get the kW output. Then divide the kW output by your panels efficiency to get the estimated number of solar panels youll need for your system.
x 1.15 efficiency factor = DC solar system size
For example, if you live in New Mexico, you average six peak sunlight hours per day. Youll need 6.2 kW DC according to the formula:
x 1.15 efficiency factor = 6.2 kW DC solar system size required
Using the example above with a 6.2 kW DC system, you can multiply this number by 1,000 to confirm that you need 6,200 watts of solar panels.
6.2 kW x 1000 = 6200 watts solar panel required
The Efficiency Of Solar Panels Under Extreme Conditions
No single customer wants to end up with solar panels that aren’t technically sound. There are major advantages of solar energy, but it’s important to have the right type of solar panel installed in your home. In order to guarantee the quality of a solar panel, it is extensively tested under extreme conditions.
Types Of Solar Panels And How They Affect Efficiency
Four major solar panel types are available to the consumer market today, each with its own advantages, disadvantages, and cell configurations:
- Monocrystalline cells are one solid silicon crystal. Mono cells provide more space for electrons to flow, resulting in a smaller, more efficient panel. The downside is they tend to be more expensive.
- Polycrystalline cells are constructed of many individual shards of silicon melted together. While not as efficient as mono cells, poly cells have a lower price point.
- Thin-film cells are thin enough to be flexible, making them ideal for small-scale or portable applications, but are not efficient enough for use in large-scale installations.
Cells can be further configured to maximize efficiency. Well go through the various solar cell types and efficiencies below, but first, a brief description of some acronyms:
- PERC reflect light back into the cell, thereby reducing the tendency of electrons to recombine. As a plus, they also absorb greater wavelengths of light, and have a high efficiency rating compared to traditional modules.
- MBB : Reduces current loss by shortening the length a current must flow across a cell wafer.
- IBC : Energy conversion occurs on the back of the cell, allowing the entire front of the cell to absorb sunlight, offering higher efficiency, yield, and reliability.
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View Your System’s Data
There are two ways to access the information about a modern solar PV system’s output from the inverter on the digital screen if it has one, and through an online account connected to your inverter.
The online data and graphs are more detailed and easier to understand and compare with your systems’ expected performance. They may give you monthly and annual kWh output.
What do those numbers on the inverter’s screen mean?
The data on the inverter’s screen isn’t as useful, but it should be able to give you three figures:
- The amount of kilowatts of power being supplied to your house and/or the grid at that point in time .
- The amount of kilowatt hours of energy it’s produced so far that day . You should check this when the sun goes down.
- The amount of kilowatt hours of energy it’s produced in total since it was installed .
TIP: Power or energy? Power is measured in watts or kilowatts . Energy is measured in kilowatt hours . If your solar panels continuously output 5kW of power for a whole 60 minutes, you will have produced 5kWh of energy.
Accessing your solar output data online
Most good quality inverters offer easy-to-read graphs and data about your system’s daily, monthly and annual energy production by logging into an app or web portal. However, it won’t tell you about you energy consumption on site.
We found that 32% of people track the performance of their system using the online interface for the inverter.
Extensive Testing Of Solar Panel Efficiency Under Extreme Conditions
Solar panel efficiency testing is carried out in order to prevent low quality solar panels from being sold in the market. The manufacturer has to prove that the solar cells have long term durability and long term efficiency. Solar panels available in the UK market are certified by first passing extensive testing.
Usually, solar cells are tested in state of the art, fully automated solar panel testing facilities. This high standard in testing enables categorisation of solar panel efficiency in groups with similar power outputs.
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How To Test Solar Panel Output
To test your solar panels, you will need to perform a fairly simple calculation. Basically, you will need to multiply the volts and amps, as this will give you an accurate total wattage:
Volts x Amps = watts
So, to determine the power that your solar panel is generating, you will need to first measure the amperage and voltage.
Start by Noting the Power Rating:
One of the first things you will want to take note of is the actual power rating of your solar panels. As discussed above, this wattage rating will not necessarily reflect the amount of electricity your solar panels can generate, as plenty of variables can influence performance, but it is still useful information to have, as it will give you an idea of how well your solar panels are performing in relation to their maximum potential.
When solar panels are given a power rating, the number is based off a laboratory test, where the solar panel is exposed to an hour of simulated sunlight that measures 1,000 watts per square meter. During these tests, the solar panels are also kept at a constant temperature of 77 F, as temperature fluctuations can also impact performance.
So, if a solar panel has a power rating of 300W, that means it produced 300 watts of electricity after being tested in ideal conditions. Again, if you were to purchase this same 300W solar panel, it would likely produce less power than this, which is why it is important to test its performance for yourself.
Measure the Solar Panel Amperage:
What Affects Solar Panel Efficiency
The limitation in solar cell efficiency directly affects how efficiently a solar panel converts solar energy into electricity.
In physics, the ShockleyQueisser limit refers to the maximum theoretical efficiency of a solar cell using a single p-n junction to collect power from the cell where the only loss mechanism is radiative recombination in the solar cell. It was first calculated by William Shockley and Hans-Joachim Queisser at Shockley Semiconductor in 1961, giving a maximum efficiency of 30% at 1.1 eV. Wikipedia.
This boils down to the materials used, the reflective efficiency, and how well the solar panel handles heat.
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Adjust For Solar Panel Degradation
Like other things, solar panels degrade over time. The National Renewable Energy Laboratory says that solar panels lose 0.8 percent of their output every year.
Suppose your solar panel produces 100% of its rated power output when brand new. After one year, this solar panel will only be able to yield 99.2% power. Within a decade, the figure will only be 92%.
In our example, let us say you already have a 4-year old solar panel. With our computed operating efficiency of 15.5%, we can subtract 3.2% to get an efficiency rating of 12.3%.
Know The Modules Maximum Power Capacity
You can easily know this by looking at the module datasheet, or by looking at the back of the solar panel itself. It will have its details shown on the back sticker usually. They normally label it as Pmax or maximum power of the module. They normally put it on the model name itself so this is not a hard thing to do.
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What Determines Solar Panel Efficiency
There are several factors that determine how efficient a solar panel is. At its core, a solar panel cells efficiency is determined by how much incoming sunlight the cell can convert into usable electricity. But what factors into that end conversion rate? There are several items that photovoltaic cell researchers and manufacturers consider when designing and producing high efficiency solar panels:
Additionally, factors like being able to absorb light on both sides of a cell and being able to absorb variable wavelengths of light change the efficiency equation for solar panels. All in all, there are a multitude of levers that scientists and researchers can pull when working on improving a solar panel cells efficiency. In the end, its all about converting more incoming sunlight into electricity.
Check out our article on different types of solar panels to learn more.
Solar Panel Testing For Amps
To test solar panel amperage output, put your solar panel in direct sunlight, set your multi-meter to the “amps” setting and…
That’s all there is to testing solar panels and making sure they work right!
After doing your solar panel testing, you should find that the solar panel output is about 18 volts and 3.5 amps.
Whenever you have these two values you can figure out the wattage by multiplying them together.
Volts x Amps = Watts
So… 18 Volts x 3.5 Amps = 63 Watts
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What Is Solar Cell Efficiency
When discussing solar cell efficiency, we mean the amount of sunlight that hits a solar panel and is converted into electricity. A solar panel is only as efficient as its weakest link: the cell. Cells, made of silicon, absorb photons and convert them to electricity.
Not all photons are absorbed, however: Depending on the wavelength of light hitting the cell, some photons are reflected and others pass through while others are absorbed and produce heat. Whats left are able to separate electrons from the silicon, thus producing energy.
The age-old struggle of solar cell design is designing cells to maximize photon receptivity by improving the following factors:
- Material. The type of material plays a critical role in overall panel efficiency. The most efficient cells incorporate the purest silicon. Impurities can lead to recombination, which results from electrons recombining when they encounter an impurity or defect in the cells crystalline structure.
- Wiring and busing. Cells with multiple busbars and passivation help efficiently capture and transfer electricity.
- Reflection. Minimizing the amount of light reflected off the cell is also an important factor affecting efficiency. Thus cells treated with anti-reflective coatings perform best.
Choosing Optimum Transparent Conductor
The illuminated side of some types of solar cells, thin films, have a transparent conducting film to allow light to enter into the active material and to collect the generated charge carriers. Typically, films with high transmittance and high electrical conductance such as indium tin oxide, conducting polymers or conducting nanowire networks are used for the purpose. There is a trade-off between high transmittance and electrical conductance, thus optimum density of conducting nanowires or conducting network structure should be chosen for high efficiency.
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Understanding Of Factors Affecting Solar Panel Output
Manufacturers provide technical information about their solar panels, including wattage, amperes, and voltage.
However, these figures represent the ideal circumstances, such as a 25-degree Celsius environmental temperature and non-deteriorating solar panels.
Your solar panels ability to convert solar energy to electricity is a crucial factor. No solar cell can convert 100% of absorbed light energy, generating only 20% at most.
Different locations also have varying amounts of sunlight hitting the ground surface, affecting the solar panels power output. For example, solar panels in colder regions have a lower electrical yield than systems in warmer locations.
There is also the effect of wear on solar panel efficiency. Solar panels deteriorate over time, reducing their power output by as much as 0.8% annually. Some high-end products have an output reduction of only 0.3%.
Standard Vs Premium Panels
Its important to consider efficiency ratings when placing your solar panels. Ideally, youll be able to get high-efficiency solar panels and place them in a location that gets a lot of sun. However, if youre locating your panels in an area that gets a lot of sun, you could get away with installing panels that have only an average or relatively low efficiency rating, since they will get maximum exposure. If youre installing panels in a location that doesnt get a lot of sun, however, youll want to invest in panels that have a higher efficiency rating so that you maximize the amount of energy you get, especially if the roof space is constrained.Another issue that affects your solar panels output is its degradation rate. Over time, solar panels produce less energy. The rate at which they decline in their ability to produce energy is known as the degradation rate.
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Diagnosing Your System Health Using Power
In order to use the power output of your solar system to see if it is performing well you will want to measure it under good conditions. If your inverter information is available online then it should be easy. If its not online then youre going to have to read the inverter display screen yourself.
You will want to check the power output when the sun is directly over the panels. Or at least as directly over them as it will get on that day. This will be at solar noon for north facing panels. It is best to check when this is at your location as it usually wont be at 12 oclock on the dot. But half an hour on either side of solar noon will make little difference.
If your panels face west the sun will be directly over them around 1 hour and 20 minutes after solar noon and around that long before if they face east. If your panels face in more than one direction then split the difference.
If your panels face in a northerly direction from northeast through to northwest and the power output is roughly 80% of the total panel capacity then your system is probably working fine.
If your panels face east or west and the power output is around 70% of the total panel capacity then your system is also probably performing fine. If you have panels facing in more than one direction, then split the difference again.
What Is ‘solar Panel Degradation Rate’
Over time, solar panels lose their ability to absorb sunlight and convert it into solar energy due to factors such as hotter weather and the natural reduction in chemical potency within the panel. This is what is referred to as the degradation rate.
The lower the degradation rate, the better the panel. When a solar panel has a lower degradation rate, it will produce more energy over its lifetime.
Degradation rates vary from one brand to another higher-quality panels have a lower degradation rate versus lower-quality panels. This is important to keep in mind when doing a solar panel comparison since it might make more sense in the long run to spend more money on higher quality panels.
According to a National Renewable Energy Laboratory study, premium modern solar panel manufacturers such as Panasonic and LG offer panels with degradation rates as low as 0.30% per year.
The worst degradation rate is .80% a year, but as a benchmark, you can expect an average degradation rate of .50% a year for any panel.
| Panel type | |
|---|---|
| 17.53% | 82.47% |
For most Tier 1 solar panels, the degradation rate is .30% meaning that each year, the panels performance is reduced by .30%. Over 25 years, that adds up to a total of 6.96% meaning your panels will operate at 93.04% of their original capacity in 2045.
If you invest in Tier 2 solar panels, your panels will degrade .50% each year and at the end of a 25-year warranty, they will operate at about 88.67% of their original capacity.
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What Are The Most Efficient Solar Panels In 2021
Heres a rundown of the ten most efficient consumer solar panels available at the time of publishing :
- SunPower Maxeon 3 , 22.8% efficient
- LG Neon R , 22% efficient
- REC Alpha Pure , 21.9% efficient
- Panasonic EverVolt , 21.7% efficient
- Silfab Elite BK , 21.4% efficient
- Jinko Solar Tiger N-type 66TR , 21.4% efficient
- FuturaSun FU 360 M Zebra , 21.3% efficient
- Hyundai HiE-S400UF , 21.3% efficient
- Trina Solar Vertex S , 21.1% efficient
- SPIC Solar Andromeda , 21% efficient
Purchasing New Solar Panels
If you are unhappy with the output of your solar panels and you would like to replace them, or if you would simply like to add additional solar panels to your solar power system, we can help.
Our collection of Foldable Solar Panel Suitcases and Blankets is perfect for those that are in the market for portable solar panels. We carry a wide range of these convenient solar panels from some of the best manufacturers in the solar industry.
We also carry an extensive range of Renogy Solar Panels, Inverters, Solar Batteries, and More. Renogy is one of the more reputable brands in the residential solar power market and they are known for balancing performance with affordability, so the Renogy brand is definitely worth taking a look at if you are planning to upgrade your existing solar power system, or build a completely new one.
If you are looking for a reliable and efficient solar panel at a reasonable price, we highly recommend this High Efficiency 200W 12V Monocrystalline Solar Panel. It features a straightforward plug-and-play junction box, an anti-reflective tempered glass cover, efficient mono PERC technology, and a pre-drilled aluminum case. Best of all, it has a 25-year limited power output warranty, as well as a full 5-year warranty on materials and workmanship.
Solar Panel Kits:
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