SOURCES OF ENERGY
The sun is the source of all the energy on earth, directly or indirectly (except nuclear energy).
Coal, petroleum, wind, Hydro, nuclear fuel, and fire-wood have been the major sources of energy conventionally.
All the plant (tree) matter on earth is produced by photosynthesis, using Sun’s energy. Animal matter is derived from plants (directly or indirectly).
Coal was formed millions of years ago by the fossilization of trees.
Petroleum likewise was formed from animal matter.
Whereas coal and petroleum are continuously depleting, the other sources are renewable. The sun causes those sources to be perpetual.
Moreover, coal and petroleum are used by means of combustion which results in CO2 generation. One kg of carbon results in 3.7kg of CO2. This is equal to about 550 liters.
RENEWABLE ENERGY
Electrical energy is the most versatile form of energy.
Hydroelectric energy is produced when rainwater is collected in dams and is used for running turbines. Rain is caused by the sun, year after year.
Similarly, wind, ocean currents, and waves, which are sources of renewable energy can also be converted into electrical energy for ease of use.
SOLAR PHOTOVOLTAIC ENERGY
The energy in sun rays can be directly converted into electricity by using solar photovoltaic (P.V.) panels. In the past 10 years, conversion efficiency has been going up due to technological advancement. In the case of silicon PV panels efficiency has increased from 14% to 25%.
The up-gradation has been as below:
From Poly Crystalline silicon PV panels to Mono Crystalline panels and onto Mono PERC and further to mono facial mono-PERC half-cut and again to bifacial mono-PERC half-cut solar PV panels there has been a steady increase in efficiency.
All the above are commercially available as of date. Extensive research is happening to improve the efficiency of silicon solar panels and solar panels made of other materials.
The most common size of silicon panels is about 1mX2m, with weight varying from 20-28kg. Bigger panels are not in vogue due to consideration of mechanical strength.
Panels rated 1 kilowatt generate 1 KW power under standard test conditions irrespective of efficiency.
All that you need is more area for lower-efficiency panels.
Huge wind turbines are contributing to the electric grid in a big way.
It should be understood that both solar PV and wind energy are highly variable from moment to moment and have limited stand-alone applications.
In general electric motors, heaters, lights, etc. need a steady source of power.
The electric grid uses hydro-electric generators, nuclear generators, coal-fired and oil-fired thermal power plants which are steady sources of electrical energy,
Wind and solar can form, maybe 20% of the grid source, so that grid does not become imbalanced. Wind/solar energy can be stored in batteries or by pumping water to high-level dams. The stored water can be used to operate hydroelectric turbines subsequently. However, there is considerable wastage.
One familiar example of the usage of solar electric energy is the operation of irrigation pumps by including a variable frequency drive in the system, whereby the need for the battery is eliminated.
On-grid vs Off- Grid
On-grid
On- grid system consists of solar PV panels, a grid-tie inverter, and the electric grid. When power is to be pumped into the electric grid the waveform and the voltage have to match 100%.It is called grid synchronization.
Moreover, in case of grid failure, the solar inverter has to be shut off simultaneously This is called anti- islanding provision.
Off-grid
OFF- Grid solar system consists of solar PV panels, solar inverter, and battery. Steady electric power is supplied to the load (motors, heaters, lights, etc.).
