Are you buying a Solar Power Plant?

Introduction

 

Let us have a quick recap of the solar cell technology that we have studied earlier in our engineering courses so that we are able to make a well-informed decision while buying a solar power plant.

 

1954 was the year when the first solar cell was fabricated in the Bell Labs, which was the first practical solar cell made. Of course, over one hundred years had flown by since the invention of the photovoltaic effect in 1839 by the French scientist Edmond Becquerel. (Don’t confuse him with Henri Becquerel who won the Nobel on Radioactivity in the early twentieth century).

 

Since then, many developments have taken place so much so, there are many buildings sporting a solar panel, today.

 

Mono, Poly and Thin-film

 

Technology wise we can differentiate the panels as Monocrystalline, Polycrystalline and Thin-film. Monocrystalline is the case of silicon crystallized and made into a single bar. From this bar, slices of wafers are made and cut to the required size. In case of Polycrystalline wafers, multiple silicon is amalgamated to make a wafer. While one is taken out of the same bar, the other is multiple pieces brought together by heating the silicon!

 

So, what difference does that make?

 

Solar energy is but electron flow. When the crystals are seamlessly laid with no inundations as in mono crystalline, the flow is easy, faster and, therefore, more efficient. Whereas when you have dissimilar crystals of Silicon brought together and made into a wafer, every time electron passes through these boundaries, it slows down and loses its energy. Therefore, polycrystalline wafers are not so efficient.

 

In numbers while mono could be as high as 18 to 22% efficient, poly could be between 15 and 17%! That is a difference of 25% in generation.

 

On the other hand, thin-film is a deposit on a plastic substrate. This makes it flexible and cheaper. The cost comes down but it could be the least efficient of the three.

 

P-Type and N-Type Solar Cells

 

On a semiconductor silicon wafer, when you add a molecule that has one less electron compared to Silicon, that makes the wafer a positively ‘mobile’ wafer because it is the positive charges that move. Whereas if you use a molecule that has one electron more than Silicon, this excess electron moves around and therefore, it is called a N Type Solar Cell. Adding Boron creates a P Type, while adding Phosphorous creates a N Type Solar Cell!

 

Well, how does it affect my life?

 

A P-Type gets affected by light easily. And therefore, it degrades in performance faster in the first year. Whereas N-Type does not. Typical N-Type manufacturers are Panasonic and LG.

 

Newer Technologies

 

PERC stands for Passivated Emitter and Rear Cell Technology. High sounding jargon but the system is simple. It uses a thin reflector behind the cell, to stop the light rays passing through the cell. This reflector reflects back the light ray to the cell and therefore, activates the cell improving the efficiency further!

 

Simple schoolboy concept but implementation took more than a quarter century to develop!

 

Apart from PERC there is another technology called Half Cut Cells! This reduces the current flowing through the cross wires by reducing the size of the cell by half. Advantage? You get to lose lesser amount of power in the cross wires since current flowing through them is low!

 

What do I use?

 

Ideally speaking, all things being equal, you might like to adopt the one that gives you maximum efficiency. Max efficiency comes with max price as well! So naturally, the choice is between price, efficiency, space occupied and, of course, availability.

 

For instance, half cut might not be commonly available. Mono is space optimal compared to poly. Thin film can be bent to cover any contour on the surface. Cost per unit is least with poly crystalline.

 

Your choice would depend on your own requirements. A well-informed decision is always the best one. When in doubt, do not hesitate to call us, eClouds Energy LLP.