Basic Solar Components

To find out how solar panels work, you need to understand how they’re made. Many solar panels use silicon, one of the planet’s most common elements. But since creating silicon crystals of suitable quality is difficult and expensive, home solar systems are usually built from similar, but less expensive materials, such as copper, indium, gallium and selenide (CIGS).


1 These aren’t as efficient as high-quality silicon, but still provide adequate power at a reasonable cost. 

During manufacturing, small amounts of other elements are introduced to alter the electrical properties of the silicon atoms. Strips of negative (n-type) silicon, which has an extra electron and positive (p-type) silicon that is missing one electron, are sandwiched together. The combination forms a photovoltaic cell. And when multiple photovoltaic cells are placed side by side under glass, they give us common solar panels.

Inside each solar panel is a conductive metal plate connected to wires that lead to a fused array combiner. Energy from the array is sent through an inverter, which transforms the initial direct electrical current into the alternating electrical current required to power human-made structures.

Turning Solar Power Into Electricity

Visible sunlight is composed of invisible particles called photons. These have energy, but zero rest mass. When the photons collide with other particles their energy is converted to other forms depending on the kind of atoms they touch. Most collisions create only heat. 

But electricity can also be produced when the photons make electrons in the atoms so agitated that they break away and move about freely.2 The n-type silicon electrons seek out the ones in p-type silicon to replace their missing electrons and the flow between the two types produced. 

The remarkable  properties of semiconductors like silicon makes it possible to sustain the electrical imbalances. This means a steady supply of electricity as long as photons hit the solar panels. The current is collected by wires and carried throughout the system.

4 Factors That Impact Solar Electricity Production

Households should consider four major factors, during and after the installation of their residential solar systems.

1. Shade. Shaded solar panels won’t produce the same amount of energy as those in direct sunlight.3 If your roof is sun-deprived by un-trimmable trees or building, solar may not be your best choice.

2. Seasonality. Like the weather, solar energy production varies day-by-day and month-to-month. A cloudy, winter day4 won’t be as productive as a sunny, summer one. But it’s important to focus on the year-round picture. For example, snow can sometimes reflect light and improve PV performance. So in reality, a cold month will only become a solar antagonist if slush covers the panels. 

3. Tilt. Unlike a pinball machine, solar panels can benefit from a good tilting. The direction your home is facing, its location,5 and even your roof’s pitch, have a significant effect on how well a residential solar system works. Ideally, solar panels should be at the same angle as the latitude where they’re mounted. Pitches between 30 degrees to 45 degrees usually work well in most scenarios. 

4. Azimuth. The solar azimuth angle6 is the compass direction from where the sunlight is coming. At noon, the sun’s light comes from the south in the Northern Hemisphere and from the north in the Southern Hemisphere. The  wrong azimuth angle could reduce the energy output of a solar home panel by up to 35%. An azimuth of zero (facing the equator) is usually the best choice. 

Do you have questions about how solar works? Our solar advisors are here to help you.


Best solar panels for home installation 2020

Generally speaking, SunPower, LG, and Panasonic make the best solar panels on the market in 2020 due to the high efficiencies, competitive pricing, and stellar 25-year warranty offered by each brand.

  • SunPower.

  • LG.

  • Panasonic.

  • Silfab.

  • Hanwha Q CELLS.

  • Canadian Solar.

  • JinkoSolar.

  • Trina Solar.



The Cost of a Solar Electricity system varies from between £4,500 to £8000


Solar Panel Output: How Much Electricity Do They Produce?


A solar panel’s output is expressed in watts.

On average, a domestic solar panel has a power output of around 265 watts, although it can range anywhere from as little as 225 watts to more than 350 watts. The higher the wattage of a solar panel, the more electricity it can produce under the same conditions.

To calculate how much electricity a solar panel will produce in a day, you simply have to multiply its wattage by the number of sunlight hours.

For example, a home in Cambridge with a 280-watt solar panel that receives 4 hours of sunshine will generate 1,120 watt-hours (Wh) or 1.1 kilowatt-hours (kWh) of electricity that day (280 x 4).

In contrast, if that same home had a 320-watt solar panel, it would be able to produce 1,280Wh or 1.2kWh of power on that same day (320 x 4).


How much power output does your home need?

This all depends on 

a) how much electricity you use, and 

b) how much of your home you want your solar panels to power.

If your household has a particularly high energy usage or you want to solely rely on solar panels to power your home, we’d recommend getting solar panels with a high output – around 300 watts (per panel) or more.

However, if you don’t use much electricity day-to-day, or only want solar panels to subsidise some of your home’s energy usage, you can choose solar panels with a lower output – of about 225 to 275 watts.

Most homes will install several solar panels, known as a solar panel system. A typical 3-4 bedroom house will require a 3-4kWp solar panel system, typically composed of 12-16 solar panels.

The output of a solar panel system can be calculated by multiplying the wattage of each solar panel by the total number of solar panels. For example, a home in Reading with 4 250-watt solar panels would have a 1 kilowatt (kW) solar system (250 x 4).

Most domestic properties have between a 1kW and 4kW solar panel system, depending on how much power they need and the size of their roof. The table below shows you how much electricity different sized solar systems normally generate over a year, as well as how many solar panels they’re typically made up of:


Solar Panel System Size  1kW

Number of Solar Panels    4

Required Roof Space         8 sq. metres

Annual Electricity Output   850 kWh


Solar Panel System Size  2kW

Number of Solar Panels    8

Required Roof Space         14 sq. metres

Annual Electricity Output   1,700 kW

Solar Panel System Size  3kW

Number of Solar Panels    12

Required Roof Space         21 sq. metres

Annual Electricity Output   2,550 kWh

Solar Panel System Size  4kW

Number of Solar Panels    16

Required Roof Space         28 sq. metres

Annual Electricity Output   3,400 kWh


Top tip: to work out how big your solar panel system needs to be, take a look at your latest energy bill. This will show you how much electricity you have used in kWh in the last month (or however often you’re billed).

How will you know how much electricity your solar panels generate?

Your solar panels will come with a meter that will be placed in an accessible location within your home. This meter will record the amount of electricity being produced by your solar panels.

Some solar brands are also rolling out online monitoring tools which allow you to view how much power your solar panels are generating via your computer or smartphone app.

As solar panels require virtually no maintenance, it can be easy to forget about them once they’re installed on your roof. We’d recommend checking them regularly, however, to ensure they’re clean and in good condition.

It’s worth monitoring your meter frequently too, to make sure they’re generating the expected amount of power. If your solar panels’ power output is particularly low, it could be a sign of a problem.