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Solar Panels

How does solar PV work?

By Sarah Ingrams

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How does solar PV work?

Learn how solar PV systems work, what the different types of solar panels are and what else makes up a solar PV system.

Solar photovoltaic (also known as solar PV) systems convert energy from the sun into electricity. You can save money by harvesting this free electricity.

Solar PV systems can be relatively simple, with their main components being solar panels or modules. Read on to find out more about solar PV systems, including which type generates the most electricity.

Types of solar PV panels

Solar panels are made of a thin layer of semi-conducting material sandwiched between a sheet of glass and a polymer resin. When exposed to daylight, the semi-conducting material becomes 'energised' and this produces electricity.

There are four basic types of PV panel: monocrystalline, polycrystalline (or multicrystalline), hybrid and thin film (or amorphous silicon). All are made from silicon but differ in the way the material is cut and treated. 

PV panels differ in efficiency – how much of the sun's energy is used by the system per unit area – and in price. 

  • Monocrystalline cells tend to be more efficient than polycrystalline cells (13-17% efficiency).
  • Polycrystalline cells can be cheaper than monocrystalline cells but are a bit less efficient (11-15% efficiency).
  • Hybrid cells combine crystalline cells with thin film cells. They're also known as HIT solar cells. This makes the panels even more efficient (17%+), but they cost more.
  • Thin film (or amorphous silicon) cells can be the cheapest but also the least efficient. They're rarely used for residential projects.

Solar tiles and slates are also available. These are installed in the same overlapping way as ordinary roof tiles and can be more aesthetic than fitting solar panels on top of an existing roof. But solar tile systems are pricey. They can cost double the amount of an equivalent solar PV panel system – so they’re not as cost-effective.

Solar tiles aren't as cost effective as solar PV panels.

When deciding which type of solar cells to go for, it's best to look at cost-per-watt (£/W) of power output. You can do this by dividing the total cost of the solar system you are being quoted for by the total power output of the system. 

When comparing quotes, make sure you know what type of solar PV cells you are being quoted for. Check that the manufacturer you choose produces among the best solar panels.

Solar panel efficiency

More efficient panels will tend to cost more. Before taking the plunge and buying expensive panels, it's worth also taking the size of your roof into consideration. If you have enough space, cheaper, less-efficient panels could end up being more cost-effective over time. 

However, if space is limited, you would probably want to maximise efficiency to get more power out of your few panels. 

We asked solar experts and solar panel owners for their top tips. Save yourself hours of research and find out how to make the most of your solar panels.

Solar panel modules and system

A solar PV system usually comprises solar panels, an inverter, isolator switches, a PV-generation meter and cables.

Some things to think about when considering installing a solar system:

  • The more panels you can fit on your roof, the more expensive the system will be to purchase and install. But the more electricity you will produce.
  • The electricity produced by the PV panels is direct current (DC). Before it can be used in the home, it has to be converted to safer alternating current (AC) using a box called an inverter. This is often placed in the loft. 
  • It's worth noting that the inverter doesn't have the same lifespan as the panels. If it fails, a replacement inverter could cost at least £1,000.
  • For safety, isolator switches are also placed before and after the inverter.
  • A PV-generation meter is connected inside your home, so you can see a real-time display of how much electricity the system is generating. The meter also measures the amount of electricity exported to the grid, and this is used to calculate your Feed-in Tariff payment, which provides cash in return for generating your own electricity if you are registered for it.
  • Finally, if you want to export excess electricity to the grid, there will be another cable to your consumer unit (fuse box).

Worried about the cost of installing solar panels? Find out if solar PV is a good investment.