House with solar panels

How solar cells work

Aug 30, 2017 - 4min read



Solar cells are quite literally a space-age technology. Although the photovoltaic effect was first observed in 1839, it wasn’t until 1958 that solar cells were first put to significant use – in the Vanguard 1 Earth orbital satellite.

While the efficiency of solar cells has since increased dramatically, the principles of a technology that evolved to facilitate space exploration remain largely unchanged in the domestic context.

So how exactly does a PV solar cell work?

Inside a standard solar cell are two extremely thin layers of silicon crystal, sandwiched between a positively charged front contact and a negatively charged back contact.

The top layer of silicon crystal – the n-type semiconductor – has been specially treated to destabilise its atoms, giving them a surplus of electrons which they are compelled to dispose of.

The bottom layer, meanwhile – the p-type semiconductor – has been specially treated to ensure its atoms have a deficit of electrons. There is an imbalance between the two layers which the laws of physics are eager to redress.

It’s only when the silicon absorbs photons – from light – that the electrons get the requisite energy to move freely.

 

How does a solar cell work? Part one

 

When sunlight hits the top layer of silicon crystal, the electrons become ‘excited’ enough to move through the front and back metal contacts of the cell – and the movement of the electrons through this circuit creates an electric current.

 

How does a solar cell work? Part two

 

The current generated by a solar cell is, on its own, fairly small. So each solar cell becomes an individual unit in a much larger network; solar cells are linked to form a solar panel, and then solar panels are connected to create the solar arrays that, for example, would be mounted on a roof.

 

The solar cell panel array

 

The final piece of the puzzle is an inverter, which converts the DC electricity produced by solar arrays into the AC electricity which is compatible with the mains supply in your home. 

 

The solar array and your house

 

With the option of adding battery storage into the mix, energy users can gain greater control over their supply by being able to select what type of energy they use at certain times of the day. Solar-generated electricity stored in a battery can be used whenever is most convenient and cost effective, cutting energy bills by decreasing reliance on more expensive energy from the national grid.

Now, with the cost of generating solar power cheaper than it has ever been before – and continuing to fall – the stage is set for the number of UK homes sporting solar panels to increase dramatically from the current figure of 2 million.

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