Eli5: solar power?


how does solar power work?

what are the advantages and disadvantages with solar power?

In: 0

There are different types. Mostly it just comes down to heating water or other things up with sunlight up or creating electricity with the photovoltaic effect by shining light on certain semi-conductors.

The big problem is that once set up these things work without requiring additional fuel or creating additional emissions.

The downside is that they only work as long as the sun shines and additional measures must be taken to store heat or electricity for the night.

It also creates DC which has to be converted into AC first.

Added issues with electricity created by solar panels is that unlike hydro or nuclear or fossil fuel burning power plants no moving parts are involved. This is a benefit when it comes to maintenance but also means they lack any sort of ability to store energy in turning generators like a flywheel.

A big advantage is that unlike most other types of power generation it can be done on a small scale. With each home having its own solar panels on its roof. It give independence.

Said independence comes at a price to utilities and the ones paying for the upkeep of the grid though. If it is every man for himself the very rich and the very poor lose out.

One big advantage though is that it has become cheaper and cheaper over they ears and reached a point where solar power is cheaper than most alternatives if you excluded all active and passive subsidies by governments.

Don’t forget iirc the most efficient solar cell is only 25.6 efficient and loses 0.5 efficiency per year.

Electricity is moving free electrons. Electrons are normally connected to atoms. You can pop them off their atoms with a bunch of different methods. One is to wave a magnet near them, which is how most generators work – the part that waves the magnet is different in a coal plant and a hydro dam, but the generator side is the same.

Another way to pop the electrons off is to shine light on them. The light hits the electrons and knocks them right off. The problems is that normally they won’t get very far, they’ll move an atom or two and then stick to another atom. So if you just leave a block of metal out in the sun it just warms up because all these electrons are wiggling about, but you won’t get any electricity out of it.

So the trick is this: place a trap door somewhere so the electrons that go through it can’t go back. We can make these trap doors, they are called semiconductors – or more accurately, [PN-junctions](https://en.wikipedia.org/wiki/P–n_junction). When there is one of these around, the electrons that get popped off the atoms find themselves being pulled toward this layer, and once they get there they sort of go through the door and suddenly find themselves being pushed away from it – in real solar cells, they are attracted towards a layer just under the front surface, and when they get through it, they are pushed right up onto the front.

Now if you just take one of these and put it in the light, this process will only happen for a brief period. The electrons will start moving and get trapped at the front, but eventually enough will move that there are all these free electrons on the front and all these electron-less atoms on the back. In this case it’s difficult for new electrons to move, like charges repel, so the force pulling them forward is offset by all the electrons that went before.

So, put wires on the front and back. Now when then electrons gather at front and can just move through the wire to get off. Now new electrons can come up from the bottom again.

And that’s basically all there is to it. There’s a metric crapload of materials science to make those cells and put the wires on the front and everything else, but really, it’s just light knocking off electrons and a pn-junction to trap them.