Going solar is a big step for mankind, and it has helped us cut costs of power. It gave us a better control of our choices for sources of energy and allowed us to invest in a clean and green future. But before we think of what it can do for us, we need to look at the many aspects of the solar energy definition and learn more about it.
Let’s take a closer look at these aspects.
Solar Energy Definition
If you look at it in the simplest of terms, solar power is energy that comes from the sun. It is a major part of green living and is a great substitute for fossil fuels. Like wind power, solar power has become a trending, popular way to provide electric power to homes and buildings. Most important of all, it is a natural source of power that is both cheap and eco-friendly over the long term.
Solar power is derived from sunlight and is converted to other forms like heat and electric power. It can be renewed and sustained, and can be harnessed for a number of purposes. Today, big companies like Google, Apple, and Microsoft invest in solar power, since it is cheaper than fossil fuels. Solar power avoids the depletion of Earth’s resources, along with the harmful effects of extraction, spills, and pollution.
How Solar Power is Produced
To learn more about the solar energy definition, we need to look at how it is produced. Solar power is converted to usable electric power through direct and indirect means.
Photovoltaic cells (PV) are a direct way of harnessing the power of the sun. They are also called solar cells or solar panels. Standard PV cells can be installed on building windows and can be a cheap way of powering up such buildings.
Concentrated solar power (CSP) is the indirect way of harnessing solar power. It uses lenses or reflectors to collect more of the sun’s thermal energy. This power is applied to molten salts or oil that retains heat for steam turbines throughout the night.
Direct PV System
PV cells and systems convert light into an electric current by means of the photovoltaic effect. At first, they were used solely as a source of power for small and medium-sized equipment. In the 80s, we saw the advent of solar calculators that were powered by single solar cells. Nowadays, PV systems can be installed on rooftops to power homes and buildings. Today, the Ivanpah is the largest solar power plant in the world, and it can generate up to 392 MW of power.
The solar energy definition involves the direct collection of sunlight through PV systems. Solar panels are made of semiconductors, which are 2 sheets of silicon that are split by an electric field. This is designed to capture the photons from sunlight.
How is this done? The system involves 2 layers, the N-layer and the P-layer. The N-layer is made of silicon atoms that have extra electrons, while the P-layer is made of silicon atoms that are missing electrons. When sunlight is captured, the P-layer directs its electrons to the N-layer, creating a circuit back to it.
PV systems produce direct current (DC) that depends on the amount of sunlight. Some systems use inverters to convert this power to the certain desired voltages. This is done through multiple solar cells that are connected inside modules.
The solar cell came a long way since it was invented. Back in the 1950’s, solar cells cost about $286 per watt and are 4.5 to 6% efficient. Nowadays, many PV systems are already being used in homes across developed countries. These grid-connected PV systems are effective in storing power and can be used at night or at other times of limited sunlight.
Even though PV systems are stand-alone power systems, certain add-ons like satellites, lighthouses, batteries can be used to increase storage.
Concentrated Solar Power
CSPs use lenses, mirrors and tracking systems to focus a large area of sunlight into a small beam. The power contained is used to heat a working fluid, and this fluid flows through pipes. The heat is then transferred to water and converts it to steam. Electric power is then made through a turbine.
This indirect method of getting solar power can be done in many ways. These include parabolic troughs, compact linear Fresnel reflectors, Stirling dishes and solar power towers. Thermal heat can be stored and it can provide enough power for up to 24 hours. Although they differ in many ways, these methods all use a working fluid to produce solar power.
A parabolic trough consists of a linear reflector that focuses light onto a receiver, and this receiver is located along the reflector’s focal line. This receiver is a tube that is right in the middle of the mirror and is filled with a working fluid. The reflector is programmed to follow the sun during daylight hours by tracking along a single axis. Examples of these are the SEGS plant and Acciona’s Nevada Solar One near Boulder City, Nevada.
Compact linear Fresnel reflectors are CSPs that utilize thin mirror strips to focus sunlight onto two tubes with working fluid. These mirror strips are more effective and cheaper than flat mirrors and can be placed in the same amount of space. As a result, more sunlight is gathered. This type of CSPs can be used in either large or more compact plants.
The Stirling solar dish combines a trough with an electric generator. These are more effective than PV cells and have a longer lifespan. One great example is the Big Dish in Canberra, Australia that can produce up to 50 kW of solar power.
Lastly, solar power towers use an array of tracking reflectors. They can focus sunlight on a central receiver atop a tower. To date, solar power towers are cheaper and are more effective in producing and storing solar power.
A hybrid system is a fusion of a PV system and a CSP. It can also be a solar system combined with other forms of power like wind or biogas. This combined form is also good because it enables the system to modulate power output as a function of demand. It also reduces the fluctuating nature of solar power. Such systems are most often found on islands.
The Benefits of Solar Power
In a way, there is no single way to define solar power, and we cannot see the best solar power definition without looking at its benefits. Solar power is energy that can be used over and over again, and we have an endless supply of it.
Solar energy is enough to power up homes and buildings and saves a lot of money for households and companies. It’s a clean power source for many devices, from furnaces, water heaters and ovens to mobile phones, chargers, and watches.
And solar power is getting way cheaper than before. Over the years, the cost of solar power has fallen, and it is possible to create large-scale PV systems and CSPs at much lower cost. And these systems can now produce hundreds of megawatts of clean energy. The PV station in Qinghai, China can produce up to 850 MW of power.
Solar power can now be used in both small- and large-scale systems, and it is getting easier to use. Most important of all, it doesn’t produce any greenhouse gas emissions, air or water pollution.