How do solar panels produce electricity?

The process of generating solar energy can be a slightly mysterious topic to some. Have no worries, we are here to make it easy for you to learn how solar panels produce electricity.

The basic solar components

The first step in knowing how solar panels work is to understand how they’re made. Many of them use silicon as a go-to material, one of the most common elements found on our planet. Since creating silicon crystals of suitable quality is a difficult and expensive process, home-solar electric systems are usually built from similar, but less expensive materials¹. Like copper, indium, gallium, and selenide (CIGS); which aren’t as efficient as high-quality silicon, yet still, provide adequate amounts of power –– at a reasonable cost –– for most residential needs. It’s a value win!

During manufacturing, small amounts of other elements are introduced to alter the electrical charges of the silicon atoms. This results in strips of negative (n-type) silicon, which has an extra electron; and positive (p-type) silicon, which is missing one electron. Don’t feel bad for this last guy, though. When sandwiched together, these two types of silicon form a photovoltaic cell –– and when multiple photovoltaic cells are placed under glass simultaneously, they give us the cool solar panels we see atop buildings today. That’s what we call good teamwork.

Inside each solar panel, there’s a conductive metal plate connected to wires that lead to a fused array combiner. A device is used to collect energy through an inverter, where the energy’s natural-direct electrical current is changed to the alternating electrical current required to power human-made structures. Yup, just like your lovely home.

Transforming solar power into electricity

Sunlight is a form of energy consisting of invisible particles called photons, that have energy, but zero rest mass. Maybe laying off the coffee for a few days would help. When photons come in contact with other particles, energy expands in several ways depending on the kind of atoms they touch. Most times, heat is generated when this happens. Like Paris would say, “That’s hot!”

On the other hand, electricity is produced when electrons circle atoms², the reasoning behind why photovoltaic cells contain materials with different electrical charges. See, when the Sun hits a silicon crystal, the electrons inside of it begin to jump up and down. And eventually, some of them become so charged up, they break free and move more freely. The n-type silicon electrons seek out the ones in p-type silicon to replace the missing electrons within their atoms — producing an electrical current from the motion of these electrons. 

The amazing semiconductor qualities of silicon (and comparable materials) make it possible to sustain constant electron imbalances. Meaning, a steady supply of solar electricity is going to be at hand every time the photons hit the solar panels — a current collected by wires and carried throughout the system. That wasn’t too complicated, right?

4 factors that mess with solar electricity production

You’ve solved the solar-energy-production puzzle. Yay! Now, it’s important to be aware of the factors that must be carefully considered before, during and after the design and installation of any solar system. Here are the infamous four:

1. Shade: You may already know this, but shaded solar panels³ won’t produce the same amount of energy as those in direct sunlight. So, if your roof is sun-deprived by un-trimmable trees or non-removable elements; solar may not be the best solution for you. At Sunrun, we offer effective solutions to help prevent excessive performance loss. We can leave the shady characters for a new Netflix series. Don’t you agree?

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; the important thing here is to focus on the year-round sunny 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 the panels are covered with slush. If Frosty the Snowman comes, he will be asked to leave. Sorry, not sorry.

3. Tilt: Unlike a pinball machine, solar panels can benefit from a good tilting. The location, the direction your home is facing⁵, and even your roof’s pitch, have a deep effect on how a system works. Ideally, solar panels should be at the same angle as the latitude where they’re mounted — and pitches between 30-45 degrees usually work well in most scenarios. Happiness is a matter of perspective, indeed.

4. Azimuth: The azimuth angle⁶ is the compass direction from where the sunlight is coming. At solar noon, the Sun’s light comes from the south in the Northern Hemisphere and from the north in the Southern Hemisphere. A wrong azimuth angle could reduce the energy output of a solar PV up to 35%. Quite a lot! Luckily, our system designers tend to use an azimuth of either zero or facing the Equator to avoid any issues. We’re proud to have nerds on our team.