The Electrical Characteristics Of A Photovoltaic Array
The electrical characteristics of a are summarised in the relationship between the output current and voltage. The amount and intensity of solar insolation controls the amount of output current , and the operating temperature of the solar cells affects the output voltage of the PV array. Photovoltaic panel curves that summarise the relationship between the current and voltage are given by the manufacturers and are given as:
What Is Solar Energy
Simply put, solar is the most abundant source of energy on Earth. About 173,000 terawatts of solar energy strike the Earth at any given time – more than 10,000 times the world’s total energy needs.
By capturing the sun’s energy and turning it into electricity for your home or business, solar energy is a key solution in combating the current climate crisis and reducing our dependence on fossil fuels.
Basic Steps In Solar Energy Generation And Transmission
Now that we have a basic idea of the generation and flow of solar electricity, lets take a deeper dive into the science behind the solar photovoltaic panel.
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What Are The Different Types Of Solar Panels
Direct solar power is generated from solar rays shining down on the surface of the earth. These rays can currently be collected by two methods via solar PV panels that we see on many a roof top or solar farms, and by solar thermal systems.
For the purpose of this blog, well mainly be talking about domestic solar technologies, rather than power plants.
The two types of solar panels are solar thermal panels and solar PV panels. Although they may look similar, they have very different functions.
In a nutshell, solar thermal technology produces heat, whilst solar PV produces electricity.
Solar thermal and solar pv can work alone, or they can work together.
Connecting Solar Panels In Parallel
Stringing solar panels in parallel is a bit more complicated. Rather than connecting the positive terminal of one panel to the negative terminal of the next, when stringing in parallel, the positive terminals of all the panels on the string are connected to one wire and the negative terminals are all connected to another wire.
When stringing panels in parallel, each additional panel increases the current of the circuit, however, the voltage of the circuit remains the same . Because of this, a benefit of stringing in series is that if one panel is heavily shaded, the rest of the panels can operate normally and the current of the entire string will not be reduced.
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How Do Solar Thermal Panels Work
These solar heating panels are comprised of tubes filled with a combination of glycol and antifreeze. These liquid filled tubes are aligned next to one another that are placed on the roof to absorb heat from the sun.
Once hot, the liquid is transported to a copper coil which in turn warms the hot water tank or cylinder, ready for use. Solar thermal energy storage is kept as efficient as possible, via the use of a pump which moves the liquid through the system in order to prevent the liquid from cooling down the water in the tank on cold days.
In slow and medium temperature collectors are either flat plate panels or tubes. Collectors for high temperatures can be concentrated systems called parabolic trough, Fresnel reflectors, dish Stirling and solar towers.
Solar thermal systems can be combined to work with gas central heating to make sure the home is covered during winter months.
However, for those wishing to completely move away from fossil fuels, there is the thermodynamic system. This uses an in built compressor to heat water so you never run out.
Install Solar Panels Today To Start Generating Energy From The Sun
Solar photovoltaic cells are the building blocks of solar panels, and any property owner can start generating free electricity from the sun with a solar panel installation. On the EnergySage Marketplace, you can register your property to start receiving solar installation quotes from qualified installers. While all quotes involve solar panels made from photovoltaic cells, panel output can change based on equipment quality. If you are specifically interested in seeing quotes for high-efficiency solar panels, simply leave a note on your profile to notify installers.
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What Do You Need To Live Off
What makes going off-grid unfeasible for some is that their homes werent built with self-sufficiency in mind. Meeting all of your energy needs on-site necessitates smart planning energy efficiency, an unobstructed south-facing roof, good insulation and more. The needs of living efficiently go far beyond the question how many solar panels do I need to live off-grid? .
Spending Money On A Quality Charge Controller Is A Good Investment
Without any doubt, a quality charge controller will protect and increase the battery life of your solar system and also helps in monitoring and quick troubleshooting. When using the right charge controller the lifetime of your battery bank can easily be extended with several months. As a charge controller only accounts for a small portion of the overall solar system cost, its highly recommended to purchase a quality charge controller.
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What Does Pv Or Photovoltaic Mean
Youve probably heard of it, but what does it actually mean?
In the solar power industry, the letters PV stand for photovoltaic, the name of the technology that makes solar panels possible. In simple terms, a solar panel can be described as the opposite to an LED lamp. Both devices use semiconductor materials, and they have opposite functions: an LED bulb converts electricity into light, while a solar panel converts light into electric power.
In spite of their name, solar panels generate electricity with any light source that is bright enough, and not only with sunlight. However, sunlight is abundant and free, while lighting fixtures use electricity. Solar panels are not combined with lamps, simply because the electricity consumed is more than the electricity produced you would actually lose money by doing this.
Solar panels are divided into photovoltaic cells, and most models have 60 or 72, in a 6×10 or 6×12 distribution. Some of the latest solar panels have a half-cell design that improves their efficiency, and they have 120 or 144. However, the solar panel size does not increase because each PV cell is only half as large.
State Solar Panel Rebates & Deductions
Individual states and cities offer their own policies, incentives and credits, as well. Some utility companies will even offer 10 to 20% rebates on your installation. With these incentives, combined with the ITC, you may be able to save as much as 50%.
- Washington: Utility companies offer rebates up to $2,000
- Massachusetts: Utility companies which offer rebates of $0.50/watt and up to $625/kW.
- New York State: Tax credit of 25% for PV systems.
- Florida: Permanent sales tax exemption for solar energy products. Also several utility companies offering $500 rebates on solar water heating systems, which cost an average of just over $3,500.
Leave Solar Panel Installation to the Pros
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Do You Always Need A Solar Charge Controller
As mentioned above, the lack of a solar battery maintainer would expose the battery bank to frequent overcharges and overdischarges, which would dramatically reduce its lifespan.
This is especially valid for sealed batteries, where the charge controller is really a must.
Otherwise, such a sealed battery can either get damaged or become a safety hazard.
However, you do not need a solar battery maintainer, if you have a solar panel of very low power below 10Wp and a battery of 100 amp-hours of capacity or greater.
It is sure that such a low-power panel is not capable of overcharging such a high capacity battery.
On the other hand, a large battery capacity guarantees that the battery bank is never fully discharged.
This is only valid if the load is always connected to the above mentioned solar configuration a 10W solar panel and a 100 Ah battery bank.
In practice, if this configuration is installed at a boat or recreational vehicle , its very probable that the load might be turned off for weeks, and there is a risk of possible overcharging.
So, if you have a boat or a RV, or for whatever reason you turn off the loads from the solar system with a high capacity bank for a very long time, you should consider using a solar charge regulator.
What Is An Mppt Charge Controller
The Maximum Power Point Tracking feature enables the input power of an MPPT controller to be equal to its output power.
Therefore, if the output voltage of the solar array is higher than the battery bank voltage , an MPPT controller brings it down to 12V but compensates the drop by increasing the current, so that the power remains the same.
Since you dont lose the solar-generated power, MPPT controllers provide you with the flexibility to connect many solar panels in series thus increasing the total voltage of the array without being afraid of losing a part of the solar-generated power.
The principle of MPPT is squeezing the maximum possible solar-generated power from a solar panel by making it operate at the most efficient combination of voltage and current, also known as maximum power point.
An MPPT charge controller converts the solar-generated voltage into the optimal voltage so as to provide the maximum charging current to the battery.
The main purpose of the MPPT solar charge controller is not only to prevent your solar power system from losing from the solar-generated power but also to get the maximum power from the solar array.
An MPPT solar charge regulator forces a solar panel to operate at a voltage close to its maximum power point.
Another benefit of an MPPT controller is that it reduces the wire size needed for the wires connecting the solar array to the controller.
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The Efficiency Of Photovoltaic Systems Varies By The Type Of Photovoltaic Technology
The efficiency at which PV cells convert sunlight to electricity varies by the type of semiconductor material and PV cell technology. The efficiency of commercially available PV modules averaged less than 10% in the mid-1980s, increased to around 15% by 2015, and is now approaching 20% for state-of-the art modules. Experimental PV cells and PV cells for niche markets, such as space satellites, have achieved nearly 50% efficiency.
Troubleshooting: Low Power Situation
If your solar system is not delivering sufficient power for which it is rated for, the resulting situation is called a low power situation. This is the most common type of problem and a few, quick, troubleshooting steps will help you find the source of the problem. The factors that could contribute to a low power problem are:
Shading
This is possibly the most common cause of low voltage. Ensure that there are no trees around and that the solar panels are not blocked by shadow at any time during the day. Keep in mind that a solar systems lasts for more than 25 years and trees grow over time. Conducting a bi-annual survey of the installation site is a good idea.
Temperature
If shading is not an issue, most likely it will be the higher than normal operating temperature of the solar panels. It has been scientifically proven that the voltage drop rises with the rise in temperature. The higher the temperature, the lower will be the power output. Adding more modules in series, and therefore increasing the string voltage, will eliminate this problem. Also, make sure that theres sufficient air circulation beneath the panels and that this open space is not blocked in any way.
Bad Connections
Solar panel defects
Hotspots
Delamination
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Solar Photovoltaic Technology Basics
Solar cells, also called photovoltaic cells, convert sunlight directly into electricity.
Photovoltaics gets its name from the process of converting light to electricity , which is called the . This phenomenon was first exploited in 1954 by scientists at Bell Laboratories who created a working solar cell made from silicon that generated an electric current when exposed to sunlight. Solar cells were soon being used to power space satellites and smaller items such as calculators and watches. Today, electricity from solar cells has become cost competitive in many regions and photovoltaic systems are being deployed at large scales to help power the electric grid.
Increasing The Efficiency Of Pv Solar Cells
The efficiency of a PV cell is the amount of electrical power thats coming out of the cell compared to the energy from the light shining on itthis number demonstrates how effective the cell is at converting energy. And as mentioned, there are a variety of factors both internal and external to solar cells themselves, like light intensity and wavelength, that affect the amount of electricity a PV cell can produce.
One important element of PV semiconductors is the range of wavelengths of light the material can absorb and convert to energy. Light is made up of photons vibrating at a wide range of wavelengths, and the wavelengths that match the absorbable range of a solar semiconductor can be captured by that solar cell. A strategy that will help improve PV cell efficiency in the future is to layer multiple semiconductors together to make multijunction solar cells. Each layer of a multijunction solar cells can have a different bandgap meaning it will absorb a different part of the solar spectrum, making better use of the sunlight than a traditional single-junction cell.
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Advantages Of Solar Thermal Panels
Solar thermal hot water heating just makes sense.
A key advantage to thermal solar panels is their simplistic design. That means low maintenance costs and easy to fix.
Again, like all renewable energy, youll be saving on your energy bills. Solar thermal panels cost roughly the same as solar PV panels, but well detail more on that below.
Unlike solar PV panels, Solar thermal heating panels dont need much space. In fact they only need 3×4 m² as opposed to 10 m² that solar PV need. Thats generally because they are more efficient, able to turn 90% of the suns radiation to heat.
A solar thermal hot water system is super-efficient as it turns out up to 70% more efficient at collecting sunray heat than PV.
It is also possible to store generated energy because any domestic thermal system will always have a water tank to store the heat.
Serial And Parallel Connection Of Pv Panels
In the PV panels connected to the series, the current of each passing through the system is equal. The system voltage for any current value is the sum of all PV panel voltages. The current of the PV system with serial connection is a single PV panel short-circuit current, and the voltage is a single PV panel open-circuit voltage. The total voltage of the circuit decreases considerably when there is shading in the series of connected PV panels . Fig. 1.8 shows the IV graph of the PV panels connected in series.
Figure 1.8. IV graph of series connected PV panels.
In a parallel connected system, a single PV panel voltage is the total voltage of the system. The current of each PV panels constitutes the total PV panel current of the system. The open-circuit voltage of the system is a single PV panel open-circuit voltage. The short-circuit current is the sum of the short-circuit currents of each PV panel. The partial shading in the parallel connected PV panel system does not change the total voltage in the system. But the total current value in the PV panel system is reduced . Fig. 1.9 shows the IV graph of the parallel connected PV panels.
Figure 1.9. IV graph of parallel connected PV panels.
Bechara Nehme, … Barbar Zeghondy, in, 2021
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What Is Electric Power
Power is the rate at which energy is transferred. It is equivalent to voltage times current and is measured in Watts . In solar PV systems, an important function of the inverter in addition to converting DC power from the solar array to AC power for use in the home and on the grid is to maximize the power output of the array by varying the current and voltage.
For a more technical explanation of how current, voltage, and power interact within the context of a solar PV system, check out our article on Maximum Power Point Tracking .
In it, we discuss current-voltage curves , and power-voltage curves . These curves offer insight into the voltage and current combination at which power output is maximized.
The Definitive Guide To Solar Charge Controllers: Mppt And Pwm Charge Controllers In Off
This definitive guide to solar charge controllers also-known-as solar battery maintainers or solar charge regulators is going to reveal:
why solar panel battery maintainers are essential for any battery-based solar power system
the main types of solar charge regulators, along with their specifics and features compared
how to select the right type and size of the charge controller for your off-grid residential or mobile solar system
some commonly made mistakes upon plugging the solar power battery maintainer to the system.
If the solar battery is said to be the heart of a solar electric system, the charge controller is definitely the brain. Read on to see why!
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