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Solar targets in GW, MW, KW not in GWh, MWh, KWh

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Why are Solar targets stated in GW, MW or KW instead of in GWh, MWh or KWh?
– by Sandeep Chandra

India’ Ministry of New and Renewable Energy [MNRE], on its website has laid down India’s target  for grid-connected Solar Power as 100 GW by 2022 [revised from 20GW in 2015]

Since one GW, or gigawatt, is 1 billion watts, this suggests that installed capacity of all Solar Power Plants across the country is target to be 20 billion watts by 2022. This is equivalent to powering 200 million [or 20 crore] 100 watt light bulbs simultaneously! How cool! hand-icon1

Whether it is GW, MW or KW, these are units of power. Most people understand power in the sense of a power rating, for example, a light-bulb of 100 watts or a water pump of 5 HP or horsepower. Although, there are some others who believe power is what is in the hands of a politician or something only powerful person can enjoy! Here though, we will restrict ourselves only to power measured in watts sun-icon

Regardless of the power rating of devices at your home or office, your electricity bill is not based on the power rating of those devices, rather it is based on the amount of electrical energy those devices use. Devices with higher power rating consume energy faster than devices with lower power rating. So, it is the total electrical energy consumed that is important. Energy from the grid as much you need, when you need it – that is important. That energy is measured in KWh or MWh depending upon the size of energy demand. So, shouldn’t the total energy generated in KWh or MWh be a more important target setting than the size of the power plant in KW or MW?

Another way to look at it is this: Power is energy used over a unit of time or rate of energy consumption. As an analogy it is like speed which is distance travelled over a unit of time. To get total distance travelled you multiply speed with time, same way to get total energy consumed you multiply power with time and get KW * h = KWh. Now see for yourself, what is more important as a milestone – speed or distance you travelled? Same way what is more important -power rating or energy consumed? Get the picture. The energy generated and consumed is specified in KWH or MWH, not in KW or MW hand-icon

So, you would expect the important thing for the government should be how much energy it plans to generate because that is what people will consume. This is the people’s point of view

But wait! How will the government know how much you will consume, when you will consume? They can only plan for the eventuality that you get as much energy as you require, when you require. To do this they plan for a minimum capability. This covers your peak demand power. That is, they assume all your devices are on at full at a given time, using their peak energy. Then they work backwards to see what power capacity will provide that. And that is measured in KW or MW. Hence all power plants are rated in KW, MW or GWboy-icon

References:

  • MNRE Solar Mission http://www.mnre.gov.in/solar-mission/jnnsm/introduction-2/
  • Units of Power: 1 GW = 1,000 MW = 1,000 * 1,000 KW = 1 million KW = 1,000 * 1 million W = 1 billion W
  • Units of Electric Energy: 1 GWh = 1,000 MWh = 1 million KWh = 1 billion Wh
  • 1 HP = 745.7 watts
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