Fossil fuels are one of the greatest threats to the environment. To save the environment, we need to find alternative energy sources that can replace fossil fuels and don’t cause any harm to the environment and the earth.
Wind energy and solar energy are the two most popular green energy sources among the various alternative energy sources. Though they can’t replace fossil fuels, they help reduce our dependence on fossil fuels at a significant scale. Wind turbines can harness wind power to generate electricity and solar panels to transform the sun’s radiation into electrical energy.
Differences Between Solar Panels & Wind Turbines
Construction of Wind turbine
Wind power is also a form of solar energy. Irradiation from the sun heats the atmosphere differently at different places, and this causes a difference in atmospheric pressure that creates wind. Wind turbines transform the kinetic energy of wind into electrical energy.
It has three different components; the rotor, the generator, and the surrounding structure. The rotor includes the blades. The generator consists of an electrical generator, control electronics, a gearbox, adjustable speed drive, or a continuously variable transmission component.
The surrounding structure is the tower and rotor yaw mechanism. The tower is relatively high, and the blades are also large depending on the power. For example, an 80 meters high turbine containing the rotors assembly weighing nearly 22,000 kg can produce 1.5 MW of electricity.
In the case of a turbine large like that, the base is almost 15 meters in diameter. Also, several accelerometers and strain gauges are attached to the nacelle for structural health monitoring of wind turbines.
Also, advanced digital technologies are there to find where the defect is precisely and measure the dynamics of turbines.
Construction of Solar Panels
Solar panels consist of solar cells, and they convert the incident irradiation of the sun to electrical energy. Solar cells are constructed using crystalline silicon.
Solar cells are generally junction diodes having a slightly different structure that is more compatible with absorbing sunlight. The first layer, i.e., open to sunlight, consists of an n-type semiconductor. The other layer, i.e., the base layer, consists of a p-type semiconductor. The upper surface is coated with an anti-reflection coating.
Panels are mostly made up of a combination of cells sandwiched between a front glass plate and a rear polymer plastic back sheet supported within an aluminum frame.
The surface of the solar panel has a finger-like structure to increase the surface area to receive a large amount of irradiation. The first layer is transparent and very thin generally, and the thin glass naturally encapsulates the cells to protect them from mechanical shock. One solar panel comprises 32, 36, 48, 60, 72, 96 cells, and a panel containing 60 cells can provide up to 300 Watt.
Efficiency is a parameter that tells about the performance of any energy source or instrument. We can compare the performances of several solar cells by comparing their efficiency. This parameter is defined by the output energy (electrical energy) ratio and input energy received from the sun.
Efficiency of Solar Panels
Usually, solar panels are 15-22% efficient. The efficiency of a solar cell depends on many factors, i.e., types of panels, placement, orientation, inclination, and wiring combination of the panels, temperature and incidence of radiation time, overall weather conditions, inverter efficiency, etc.
Monocrystalline solar panels are the most efficient type of solar panels with 22-27% efficiency, whereas polycrystalline panels are only 15-20% efficient (measured in standard conditions). With the advancement of technology, scientists are hopeful about the growth of this efficiency.
A new kind of solar technology that stacks the technology from six different solar cells can ratchet up that efficiency multiple times. The record has reached 47% efficiency in the lab and nearly 40% in real-life conditions.
Efficiency of Wind Turbine
Wind efficiency is the amount of kinetic energy of the wind that converts into electrical energy. So, it’s clear that if the turbines were 100% efficient, then the wind would stop blowing, and the blades would stop and couldn’t produce electricity.
The maximum theoretical efficiency limit is 59.6%, and the average efficiency the turbines show is 35-45%. Energy efficiency doesn’t vary as much as the wind capacity factor does, and the capacity factor varies accordingly with the location and weather conditions.
It can be optimized by choosing places where ideal wind conditions prevail most of the time of the year. Increment of capacity factor is being noticed with the advancement of technology. Wind turbines manufactured in 2014 reached up to 41.2% capacity factor whereas wind turbines of 2004-2015 could reach only 31.2%.
Recent research from Oxford Brookes University has found vertical turbines to be more efficient than the traditional ones. In large-scale wind farms, these vertical turbines seem to be more appropriate. When set in pairs, they increase each other’s efficiency by 15%. This is more efficient than solar panels as they are only 15-22% efficient.
Working Principle of Solar Panels
Solar cell absorbs solar irradiation and converts solar energy into electric energy. When sunlight occurs on the solar panel, it (photons) can easily reach the junction (depletion region of p-n junction) through the thin transparent upper layer.
The photons supply sufficient energy to the junction region where electron-hole pair generation occurs. The electrons flow towards the n-side, and holes flow towards the p-side of the junction.
The carriers (electrons and holes) cannot further cross the junction because of the barrier potential. Thus the carrier concentration increases on both sides (higher electron concentration in n-side and higher hole concentration in p-side). Now a voltage is set up that is called photovoltage.
A tiny electric current starts flowing once a load is connected across the cell. These cells are connected to build solar panels, and these tiny currents/voltages sum up to provide larger current/voltage according to the need.
Working Principle of Wind Turbines
Wind turbines convert the kinetic energy of wind into electrical energy. The wind turns the turbine’s blades around a rotor that spins a generator, creating electricity.
A wind turbine converts wind’s kinetic energy into electricity using the aerodynamic force from the rotor blades. The propeller-like blades work like airplane wings or helicopter rotor blades.
Wind flows across the blades, and the air pressure decreases at one side of the blades accordingly with the speed of blowing wind. So, a difference in air pressure is created at both sides of the blades.
This pressure difference creates both lift and drag to the blades. Generally, the lift is stronger than the drag. A stronger lift causes the blades to make the rotor spin. Now, the rotor is connected to the generator (maybe directly or through a shaft or a gearbox).
This allows the generator to speed up the rotation and translate the aerodynamic force to the rotation of the turbine. This causes the generation of electricity.
So, clearly, wind energy is more efficient than solar energy.
Impact on environment
Both solar energy and wind energy are renewable and green energy, and both are ‘cleaner’ energy sources for the environment compared to fossil fuels. But that doesn’t mean they are completely free of adverse environmental consequences. Major environmental impacts are bird mortality, habitat loss, noise, visual impact, hazardous chemical usage, etc.
Environmental Impact of Solar Panels
In the case of solar energy, fossil fuels are used to extract, transport, and refine materials. Extraction of natural resources causes habitat disturbances. Silica particles released during mining and refining the materials may cause lung disease silicosis (though it can be prevented using safe equipment).
Also, solar panels emit greenhouse gases at a rate of 40-55 grams per kWh of energy generation for standard silicon panels and 25-32 grams per kWh for thin-film technology. Hopefully, this can be minimalized with newer technologies.
Fluorine and chlorine are emitted due to etching and texturing solutions and also as a component of dust particles. Wastes generated by retired panels are growing (though the amount of wastage is negligible to date), which can be a future headache. Some panels could be classified as hazardous waste due to their lead content from soldering and glass encapsulation.
Environmental Impact of Wind Energy
Wind energy has adverse health effects on the nearby population. The most frequent complaint is about the noise. The noise is irregular in intensity and so described as piercing, preoccupying, and continually surprising. The spontaneous reoccurrence of this kind of noise disturbs sleep and attention.
Also, it is described to cause headache, nausea, fatigue, vomiting, insomnia, and even temporary feeling of dizziness. Other reported effects are migraine, hearing problem, tinnitus, heart palpitation, anxiety, and depression. Altered quality of life, excessive tiredness, stress, and distress are the most commonly reported problems by people living nearby wind turbines.
When it comes to carbon emission, of course, the wind blows without any adverse effect on the environment. But the thing isn’t that straightforward.
Application of Wind Turbines
Wind turbines are used mainly commercially (Windmill is a different thing. Though that is also powered by wind energy, it has different usage than wind turbine) to generate electricity.
This electrical energy produced by wind turbines powers up houses, schools, and even businesses and farms. Commercial-scale wind power is even beneficial for local government and municipalities. Modern wind turbines have capacity ratings from 250 watts to 1.65 MW.
A 10 kW wind turbine can produce nearly 16,000 kWh annually, more than enough to power up a household. A 1.65 MW can power more than 470 average households in the U.S. This is a rather sustainable and renewable energy source having very little impact on the environment than burning fossil fuels.
Application of Solar Panels
Solar panels/cells have a variety of applications. It is used both for household and industrial purposes. In agriculture, they are used as a power source of irrigation, and they are also used to refrigerate medical supplies.
There are photovoltaic power stations that use solar panels to generate electricity. There are rooftop solar PV systems, standalone PV systems, solar hybrid power systems, concentrated photovoltaics to supply the electricity in households and industries.
PV modules also include a large variety of electric devices: solar planes, solar-powered water pumps, solar-pumped lasers, solar vehicles, smart roads, etc. Solar panels are used even on spacecraft and space stations.
The main advantage of solar cells or panels is that they are portable and so easy to fit into any electrical device.
Which is better: Solar power or Wind turbine?
Both solar energy and wind energy are cleaner and greener energy sources. So both of them can have a great impact on the environment by cutting down the generation of toxic pollutants and hopefully can help the issue of climate change so far.
But to overpower fossil fuels, it’s very important for the power sources to be cost-efficient, practical, and easily available anytime and anywhere. Both solar and wind energy have advantages over the other.
Solar energy provides a more predictable output than wind energy. In solar farms energy production rate is massive. Solar panels don’t require any particular area or space to be installed, and they can be installed on almost every rooftop of a household or office.
Also, solar panels don’t have any adverse effects on health like wind turbines. Unlike wind turbines, solar panels aren’t noisy.
In suburban areas, solar panels are a better option than a wind turbines. The rooftops of houses and other buildings are more likely to fit solar panels there. Also, it has no moving part and is thus less space-consuming. These panels come with a 20-25 year warranty, thus more secured and reliable.
In the case of a wind turbine, it can be harnessed on the night and cloudy days too. Also, wind energy is much more efficient than solar energy. They produce less carbon dioxide than solar panels (wind turbine produces 4.64g/kWh, whereas solar panels produce 70g/kWh).
Wind turbines are the best fit for rural areas (that are less popular and far away from cities). Also, wind turbines serve a lot for irrigation and drainage pumping purposes.
Still, the effectiveness of both energy sources depends upon which geographical area you are in. Solar panels produce much more kWh energy than a single wind turbine in sunnier and hot climate areas. In windy areas like seashores, wind turbines will produce more energy.
Which is the cheaper: A solar panel or a Wind turbine?
The solar panel needs a huge installation cost initially. The cost varies accordingly with the size of the panel and the type of roof. As of December 2021, the average cost in California is $2.81/Watt. A 5kW system in California has a range of installation costs from $11,942-$16,158.
Installation cost depends upon many factors. Also, it varies in different countries. Solar panels require the least maintenance; thus, the maintenance cost is also the least.
The wind turbine of about 5kW will produce energy for a household of 6 around people. Wind turbines require installation costs too. The cost depends on the size and height of the turbine and the equipment and technology used.
The average installation cost is between $50,000 and $70,000. Once built, maintenance of turbines needs an ongoing expense. It costs 1-2 cents per kWh energy produced (Operation and maintenance cost consists of insurance, land rent, service, repairing, administrative tasks, etc.).
How many Solar panels equal a Wind turbine?
Both solar panels and wind turbines are available in different sizes and capabilities. One average wind turbine can generate the same amount of electricity per kilowatt-hour, about 48704 solar panels.
To manufacture that number of solar panels costs much more energy than one wind turbine. A household of 4 people needs around 16 solar panels (thus four panels per person on average), which depends on the daily usage and the average sunshine of the place.
Can you combine solar and wind power?
Wind turbines and solar panels can be hooked up through the same wiring system, and one needs a controller capable of handling both systems.
There is a hybrid-electric system that combines wind and solar electricity. In many states and countries, wind speed is lower in summer, when the sun shines brighter, and in winter, wind speed is high, the sunshine being less bright. So, the hybrid system can provide more power according to your necessity, whatever the season is.
When neither wind speed nor sunshine is enough to generate the required power, these systems can generate power through batteries or conventional fuels such as diesel.
Despite the advantages of green energy, there is still a question of economic sustainability. Both solar energy and wind energy are growing day by day, and in the last decade, both of them have grown at a noticeable rate. And both have their unique advantages and disadvantages.
To compete with the most popular energy source, fossil fuel, we need to find cost-effective ways to store their energies so that they can be effective at any time of the year. Hopefully, the production cost, installation cost, etc., is being reduced with the advancement of technology.