Moore’s Law and Solar Energy

Moore’s law is named after the American engineer and computer scientist Gordon Moore, who in 1965 published an article in the Silicon Valley newspaper The Recorder that forecasted the impending explosion of computing power due to the nascent field of microelectronics.

What exactly is Moore’s law?

Moore’s Law posits that the processing power of computers will double every 24 months.

In other words, a computer built in 1966 will be comparable to one built today, provided they have the same number of cores and the same amounts of RAM and storage. You measure the power of a computer in terms of its mathematical ‘flops’ (FLOPs – Floating-point Operations Per Second). A FLOP is a term used to measure the computational power of a computer. The greater the number of FLOPS a computer can perform, the greater its computing power.

Gordon Moore made this prediction despite the vast differences in the nature of microelectronics and computer hardware back in 1965. At that time, all computer systems were built entirely from discrete components (transistors, valves, relays etc.), which were all manufactured in different countries at different times. With the advent of integrated circuits in the 1960s, which are now built on the scale of microns, the law still holds true. (A micron is a millionth of a meter – a millionth of a meter makes up a micron.)

Gordon Moore also made a prediction about the future of solar energy. In his 1965 paper, Moore wrote: “I believe that solar energy and digital computers are very closely connected, particularly in view of the enormous expansion in the use of computers in recent years and the corresponding increase in demand for energy.”

Indeed, over the course of the last 60 years, the applications that use computers have multiplied and are continuing to do so. For instance, in 1945, there were only a few mainframe computers in existence. By 1965, the number had risen to around 300. In 2018, there were more than 3 million internet-connected computers, and the number is growing. Moreover, much like semiconductors, the efficiency of solar cells has improved exponentially over the years, allowing for more and more power generation from the same quantity of sunshine. In other words, Moore’s law has also held true for solar energy.

How Does Solar Energy Fit In?

Solar energy takes the form of light, which can be converted into electricity through a solar cell. In the 2018 edition of its ‘State of the Energy Market’ report, the International Energy Agency (IEA) states that annual photovoltaic power generation around the world rose by 23% in 2017 to 479 gigawatts. (A gigawatt is a million megawatts and is equal to a billion watts.) This is a slightly higher figure than the previous year, primarily due to the increased demand for solar power in emerging markets such as China, India, and Chile. The power generation from solar remains significantly lower than that from traditional fuels (primarily coal and gas) used to generate electricity, but it is growing steadily.

The Exponential Nature Of Semiconductors

Semiconductors are the materials that allow electricity to flow in electronics. Without them, devices such as computers, cell phones, and even solar cells would be completely impotent. Semiconductors are generally built upon a substrate, such as silicon, germanium or gallium arsenide, and they are usually either n or p type conductors. A small n-type region in a p-type semiconductor is called a ‘p-n junction’. In this example, the substrate is p-type (has more positive charges than electrons), and the region is n-type (has more electrons than positive charges). The small band of electrons, or holes, that exist in the n-type region of the p-n junction are called ‘carriers’.

Gallium arsenide, for example, is typically used for computer logic and transistors in the microchip industry. Its most common application is in the manufacturing of solar panels.

These days, solar cells are made of thin films of silicon that are deposited onto a glass or plastic substrate. As we’ve established, silicon has been a staple of the semiconductor industry for decades due to its abundance and relative ease of use in fabricating semiconductors.

The quality of the silicon used to make solar cells has a huge impact on the cell’s overall performance. For example, the band gap of silicon that is used to make solar cells needs to be approximately 1.7 eV or higher to absorb the maximum amount of sunlight and generate electricity efficiently. (A band gap of 1.7 eV allows enough difference in energy between the electron and hole in a p-n junction to create an electric current.)

What Is The Difference Between Photovoltaic And Solar Cell?

In its simplest form, a photovoltaic cell produces electricity from sunlight by means of a p-n junction. A small voltage difference (around 0.6 V) arises across the junction when illuminated by light of the appropriate wavelength. This voltage is very small by traditional nuclear standards (around 10 V is typical) and is therefore not useful for most applications. However, for certain specialized uses, such as in spacecraft where it is used to power small sensors or in remote areas where fuel costs can be high, photovoltaics have become extremely useful and have found applications in areas such as military radar, geological exploration, and oceanography. (Source: NASA)

How Do Semiconductors Work?

The movement of carriers in a semiconductor is called ‘current flow’ or ‘electron flow’. To create a voltage across a p-n junction, electrons must be able to flow across the junction from the n-type region into the p-type region. A p-n junction is essentially a non-linear resistor, which can be extremely beneficial for certain applications such as in photovoltaics. Due to its non-linear resistance characteristic, a p-n junction has a high resistance when there is negligible current flow and a low resistance when there is an appreciable current flow. In this way, the diode functions like a switch, with a relatively high resistance when closed and a lower resistance when open. (This property also makes it ideal for use in a solar cell’s applications where it is subject to a varying load – i.e. the amount of current that flows through the device changes with the changing light intensity of the sun.)

A diode alone cannot produce a substantial amount of current. Due to its non-linear characteristic, a diode creates a short-circuit for any appreciable amount of current. This makes it extremely useful in protecting sensitive electrical components from damage in case of an accident or malfunction. (Many electrical components depend on current for their operation, and a short circuit of this nature can cause the component to malfunction or even be destroyed.)

In modern times, diodes (or other related components such as transistors and integrated circuits) are often used in combination to form circuits that are easier to design and test. A diode alone, for example, does not create a direct current (DC) of any appreciable amount. However, when used in combination with other components (e.g., transistors and integrated circuits), diodes can be used to create complex integrated circuits that are able to direct the flow of electrical current with a high degree of precision.

Why Is Silicon Important?

Silicon is non-toxic, easy to process, and relatively inexpensive. It is also naturally abundant, meaning that it is easy to obtain in large quantities.

Due to these advantages, the semiconductor industry has largely adopted silicon as the primary material for use in semiconductors. Moreover, pure silicon is relatively easy to form into any desired shape and can be used to create various electronic devices.

While the processing of silicon is relatively straightforward, there are some difficulties associated with this technique. For example, when a silicon wafer is placed under extreme pressure – such as during the formation of a diamond or graphite crystal – the silicon can suffer serious damage. This makes these two forms of carbon particularly undesirable for use in high-pressure situations such as in the formation of diamonds or graphite crystals for use in electronics. (Source: Cornell University)

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