Basics of solar power-Part I

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Sunlight is the energy source that drives our planet. Each and every thing on this planet is a receptor of sunlight. Each species uses sunlight in its own way. Plants cannot move around in search for food and hence they rely on sunlight for cooking their own food. Without the UV rays in the sunlight, humans could suffer from a disease called rickets, because it is these rays that are necessary for human bodies to produce Vitamin D which in turn allows our bodies to absorb calcium. But there’s another way we can harness this energy. It’s by converting sunlight directly into electricity or by using its thermal energy to convert water into steam, which is indirectly converted into electricity.

On an average, earth receives 164 Watts per square meter for an entire day (24 hours). Multiply that with the surface area of the earth and it receives a whooping 84 Terawatts of Power. (Earth is called Terra in Latin, different from ‘tera’ watts.) Here’s a picture of the dynamics of solar radiation reaching our planet.

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(Image: University of Oregon)

How do we collect sunlight?

We collect sunlight (solar energy) with solar panels. Solar panels are a collection or an array of photovoltaic modules. (photo = Greek phōs = “light” and “volt” = the unit of electro-motive force = last name of the Italian physicist Alessandro Volta) Photovoltaic modules are a collection of solar cells.

When particles of light aka quanta of light or photons hit these panels, they are absorbed by the semiconducting material of the panel. Example of a semiconducting material is silicon. A solar cell is made up of two types of semiconducting materials – p-type (more positive charges/holes) and n-type (more negative charges/electrons). They are sandwiched together to form a p-n junction and due to such a configuration, current flows only in one direction.

When I say photons hit this material, it means that the photons kick the electrons out of the n-type layer. The photons kick them out of their usual place and let them loose. The kicked electrons are all excited now and start moving into the p-type layer. But now they want to go back home, so they return back in a loop. This is what constitutes a flow.

In school, we’ve learnt that when electrons flow, we get electric current. This is due to difference in electric potential. Any system wants to go back to its stable state. Hence, to counteract this difference, the electrons move in a way to regain balance again (electrons get homesick).

The sandwich of p-type and n-type layers of semiconductor materials caused the electrons to flow in one direction. This kind of a flow of current is known as direct current (DC). But this is not what the appliances at our home use, do they? The appliances run on AC: alternating current. DC can be converted into AC with an inverter.

This is all for now. I’ll leave you with this song until I get back to you with the Part-II section of this blog post.


This blog post was first published at GreenHatters on February 14, 2014. Version edited for minor corrections. It’s a part of a series on solar power fundamentals.

GreenHatters is a not-for-profit initiative that cares for the environment and promotes sustainability, strives to create awareness on Energy conservation and Carbon footprint responsibility.

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4 thoughts on “Basics of solar power-Part I

  1. I had thought of venturing into this a couple of years back, just for my house but the QUOTE i got to get the sheets installed to hold the energy was so much I would have died paying the debt.

    in uk it is very expensive .. but it is good if we can harness sunlight ..

    1. Solar has gone cheaper over the years they say. In UK, March 2015 saw the highest number of installations over the past year, 9500+ for less than or equal to 4W. (4kW covers approximately 28 sq m of roof space, enough for a family of 4). Most residential places have these. Over the entire year, (April 2014-March 2015) a total of 69000+ installations with an average cost of 1949£ per kW, a little less compared to last year i.e. 51000+ with an average cost of 2080£ per kW. How much would the panels have cost you?

      I don’t understand. Recently, the decision was taken by the government of Prime Minister David Cameron, to cut those subsidies by as much as 87 percent because the solar market has been established in British households. The cuts will not affect solar installations already in place. But new solar-power systems will not be eligible for the subsidies. So does this mean the PM was right and that the installations have increased despite the removal of subsidies? Looks like.

      According to PwC, the widespread roll out of solar PV in the UK has been slowed by a number of factors such as the lack of incentives for small scale domestic installations, complexity of funding, and planning restriction. Would you like to add anything?

      1. You know the actuality is different. You have done your research which is very good. .

        Maybe I don’t earn enough or my salary as a gazetted officer is so low that I can’t afford ..

        Maybe David Cameron needs to get out of his no 10 downing street and see what is going in.

        I have a three bedroom house and I was quoted 9000 yes nine thousand pounds to get solar panels fitted..

        Now maybe those who have black money can get it done..

        The neighbourhood I work in is quite big.. and I don’t see any house with panels..

        I have also just called a distinguished solar company to quote me a price and sadly that price has gone up..:)

        1. That’s sad. Try this? :D http://billionsinchange.com/solutions/free-electric

          The Free Electric machine gives people the power to generate electricity themselves – pollution free. The machine is small, light and simple. Here’s how it works: A person pedals a hybrid bicycle. The bicycle wheel drives a flywheel, which turns a generator, which charges a battery. Pedaling for one hour yields electricity for 24 hours with no utility bill, and no exhaust, no waste.

          I don’t know how much it costs though. Do let me know if you find out!

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