Photovoltaics (PV) is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect.
There is a lot of energy that comes out of the sun. Thousands and thousands of times more than we need. And we know how to use the suns energy in a number of ways. We can try and convert it directly into electricity and that way of using the suns energy is called solar photovoltaics or Solar cells for short.
Solar cells are materials that can take the energy that comes in from the sun, in the form of photons, and convert those photons and the energy into a different kind of energy which is electricity. So it converts photons into electrons.
You can think of it like the electrons being pushed up a hill in a way. You pump water up a hill and you let it roll back down. As the water rolls back down, you can turn the wheel and do the work.
If you keep the water up on the hill, it stores the energy for you until you want it. A solar cell doesn’t store the energy, so for that you need a battery. But what a solar cell does is its constantly pumping that water up the hill and allowing it to flow back down. The important thing is that the pump is the sun and the water is electricity, it is electrons. As the electrons flow back down from the energy that pumped it (from the suns energy), we can use the energy.
Firstly, you have the active layer semiconductor and then that has to contact metal.
You have two metals on two different sides of this material. One of them is on the side that the sun is shining through. You would like that to either not take up a lot of area or be transparent, so that it is not blocking the light from the active layer.
Once you go from the active layer and the metal contacts, then you have the packaging. And the way that we do that mostly today is with glass. Glass is an active material perfect for absorbing sunlight.
If you look at glass from the point of view from the electrons, it looks like there are all these energies that an electron can sit at in the material. Then there’s this big gap, where it cant go anywhere in that gap. That top, before the electron gets to that gap is called the Valence Band. That’s the highest energy level an electron can be at in this material.
The next level up, above this gap is called the conduction band. To be an electron that can be taken out of the material, it has to make its way into that conduction band. How does it get there?
It’s given a boost of energy that makes it overcome that gap. That means as a minimum the energy from the sun that I have to generate electricity with this solar cell, is going to be equal to that gap. That gap is a fundamental property of materials.
The main limitation is cost. On average, it's around 5x more expensive than the electricity you get from natural gas. The other challenge you have is storage. For example, if you wanted up to 10% of the electricity in this country to come from solar PV, we could do that. If we wanted it to be more than that, then we’re going to need to figure out a way to store that energy efficiently, at that large of a scale.
What are the potential future applications of solar cells?
There is a lot of interest in getting off of glass because if you can get off of glass, then you can make lighter panels. This means we may be able to embed solar cells into other materials. Such as the tiles on your roof and even into fabric. They have these transparent solar cells and because they are transparent, they’re not that efficient. You would think “Why would I want a transparent not that efficient solar cell?” Well, they have a demonstration where you put one of their solar cells on top of an Amazon Kindle, and you can't tell that it's there. The Kindle never needs to be plugged in again. Even from ambient light from a room, that’s not enough to keep it charged.
We need to get solar into people’s hands and into peoples products, so that they can see that it's not actually that complicated and it can be very useful and ultimately it can do a lot of good for the world.
Here at Ideal Power, we offer Photovoltaic power supplies suitable for applications in the Photovoltaic/Solar industry. We offer an ultra-wide input voltage range of 100-1500V DC and a temperature range of -40 degrees to +70 degrees, which allow the control systems to get power from solar panels directly and ensure reliable operation. The Photovoltaic power supplies feature an isolation voltage of 4000VAC, output over-voltage protection, short circuit protection and anti-reverse connection protection which ensure the stability of the circuit.