Harnessing the sun’s power is accomplished through the use of a photovoltaic system. Basically, the word ‘photovoltaic’ is used to describe a device, which when exposed to the sun’s radiation, creates electrical power. PV systems incorporate the use of PV modules (solar panels), to generate energy from sunlight and inverters which convert that power and safely deliver it to the utility grid for our use.
A solar panel typically generates 12 volts DC. These panels can be used separately or they can be wired together in what is called a solar array. The number of panels used in the array is determined by a number of factors such as sunlight but here are many other factors that determine solar power effectiveness.

The sun delivers its energy in two forms: heat and light. Solar systems can efficiently convert either form into power for practical use. When many people hear the term “solar system” they think of solar hot water, where the sun is used to heat water for swimming pools or domestic use. This is accomplished by exposing the water to the sun’s heat prior to using it. We also make use of the sun’s heat by orienting windows towards the south (in the northern hemisphere) to take advantage of the sun’s warmth in the winter. This is called “passive” solar. This term is used to describe methods of using the sun’s energy indirectly, such as through bio-mass or heat pumps.

The term solar power system on the other hand, typically describes only those systems that convert sunlight into heat (solar thermal energy) or electricity (photovoltaic). Photovoltaic and solar thermal energy are not in direct competition – quite the contrary: they ideally complement each other and can be combined well.

How Grid-tied Solar Systems Work
A grid-tied solar power system converts sunlight into electricity. The photovoltaic (PV) modules collect the sunlight in the form of direct current (DC) electricity. The inverter changes the DC electricity into alternating current (AC) electricity for use in your home. Excess power is fed back into the public utility grid and depending on your state’s energy policies you may be eligible to receive credit on your bill.

What components are PV systems made up of?
A PV system typically consists of 4 basic components.

The PV Array: Electricity is generated by solar cells. Individual solar cells are grouped together into a solar “panel” or “module”. Then, several solar modules are grouped together to form a PV array.

The inverter: Power produced by the PV array is direct current, or DC power. That power needs to be converted to alternating current, or AC power, before it can be connected to the utility grid. The inverter is the heart of the system and is responsible for performing this conversion safely and efficiently.

The Utility Meter: the utility meter tells how much power is used as well as how much power has been fed into the utility grid.

Performance Monitoring: Various forms of meters ranging from simple displays to wireless monitors and web-based data access are used to track the performance of PV systems. There are several options available to suit your specific needs.

What does a solar cell consist of?
Over 95 % of all the solar cells produced in the world consist of the semiconductor material silicon (Si). Silicon has the advantage of being available in sufficient amounts as it is the second most common element in the Earth’s crust. Moreover, the crystal can be processed in an environmentally compatible way.
There are three cell types, depending on the type of crystal: monocrystalline, polycrystalline and amorphous. The different cell types differ in terms of their production costs and the different efficiency values. The efficiency values of amorphous cells (“thin-film cells”) are below those of the other two cell types; but then they are cheaper due to the less cost-intensive manufacturing process.

How does an inverter work?
The inverter is the “heart” of any solar system and assumes the task of efficiently converting the direct current generated by the solar cells to alternating current. Only then is it possible to feed electricity into the public utility grid safely. The inverter’s role is to be the interface between two energy sources: the DC network on one side and the AC utility grid on the other. In addition to the conversion and feed-in function, the inverter is also responsible for system control and performance optimization.

What does kilowatt peak (kWp) actually mean?
Kilowatt peak stands for peak power. This value specifies the output power achieved by a solar module under full solar radiation. Solar radiation of 1,000 watts per square meter is used to define standard conditions.
Peak power is also referred to as “nominal power” by most manufacturers. Since it is based on measurements under optimum conditions, the peak power is not the same as the power under actual radiation conditions. In practice, this will be approximately 15-20% lower due to the considerable heating of the solar cells.

Are there different degrees of efficiency?
Basically, the efficiency describes the ratio between energy outputs and inputs. At its maximum, output can be as high as input, but never higher. The result is the fact that efficiencies cannot be larger than 1. (Instead of power, you can also express the relation between the energy released and the energy provided.)
In the case of solar electricity generation, one distinguishes between cell efficiency, module efficiency and system efficiency. In commercial mass production, a cell efficiency of up to 18.3% is currently obtained, depending on the technology that is used. Module efficiency relates to the entire module surface and is therefore always slightly lower than cell efficiency. This is partly due to the non-usable spaces between the arrays of solar cells in the module. System efficiency relates to the complete solar installation. Here there is another numerical drop in value when compared to the module efficiency, this being due to conductance losses, e.g., in cables.
The inverter also converts the direct current of the solar generator into alternating current with a certain degree of efficiency. In this context, two partial efficiencies play an important role: conversion efficiency and tracking efficiency, the second of which reflects the precision and quickness of the MPP tracking. At present, state-of-the-art devices reach total efficiencies of more than 98%.

What happens when it is cloudy?
PV modules not only harness direct sunlight when the sky is clear, but also the diffused light when the sky is overcast. The brighter it is outside, the greater the output of the modules – regardless of whether the sun can be seen directly or not.

How is the photovoltaic system installed?
For a rooftop installation, there are several options open to you: the most common are on-roof or in-roof installations. The former involves the solar modules being installed above the roof on a mount, while with the latter they are integrated into the surface of the roof. Photovoltaic systems can also be installed on façades or as free-standing installations.

What is “electrical isolation”?
Inverters with transformers feature something called electrical isolation. This is a safety barrier between the solar electric circuit and the utility grid connection.
It offers two advantages: first, DC voltage from the solar array – no matter how high – cannot get through to the utility grid side and cause damage. Secondly, the direct current side is not impacted in any way by the grid’s alternating current. In the case of transformer-less inverters, which can offer higher efficiency values, an insulation and fault current monitoring system isolates the solar installation from the grid in the event of a fault.

What happens if the solar installation is struck by lightning?
Since a photovoltaic installation does not increase the probability of lightning strikes, the solar modules themselves are no more at risk than the inverter or other loads connected to the grid. However, in the rare event of the solar generator being hit by a direct lightning strike, the modules are likely to suffer considerable damage. The only thing that will help in this scenario is the integration of an external lightning protection system.
Good grounding is essential for the proper operation and safety of your solar system. Consult with your installer if you have any questions or concerns regarding system grounding.

How can solar energy be stored for later use?
Whole books have been written on the subject of energy storage alone. In the near future, we will see some dramatic advances in this area of research. Today, most energy storage is accomplished through the use of batteries. This can range from a single PV module and a car battery supplying a few 12VDC loads, to very large and sophisticated backup systems.

HOW SOLAR ENERGY BENEFITS US:
As our natural resources set to decline in the years to come, it is important for the whole world to move towards renewable sources. The main benefit of solar energy is that it can easily be deployed by both home and business users as it does not require any huge set up like in case of wind and geothermal power stations. Solar energy not only benefits individual owners, but also benefits the environment.

  • No Pollution:

    Solar energy is non-polluting, clean, reliable and renewable source of electricity. Solar energy does not require any fuel and thus avoids the problems of transportation of fuel or the storage of radioactive waste.

  • Long lasting solar cells:

    Solar energy provides cost effective solutions to energy problems where there is no electricity at all.

  • Renewable Source:

    Solar energy is a renewable source of energy and will continue to produce electricity as long as sun exists. Solar energy from sun is consistent and constant power source and can be used to harness power in remote locations.

  • Low maintenance:

    Solar cells generally do not require any maintenance. More solar panels can be added from time to time when needed. Although, solar panels have initial cost but there are no recurring costs.

  • Easy Installation:

    Solar panels are easy to install. Unlike wind and geothermal power stations which require them to be tied with drilling machines, solar panels can be installed on the rooftops which means no new space is needed and each home or business user can generate their own electricity. Moreover, they can be installed in distributed fashion which means no large scale installations are needed.

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