As the climate gets more unpredictable, it becomes more and more obvious that the utility grid is much less reliable than we assumed. Creating your own grid offers the additional safety and independence, helping to reduce emissions at the same time. Solar power is one of the easiest and safest ways to achieve this goal. Read on to discover the inner workings of this technology.
How do solar panels produce electricity?
It’s fascinating that these glass-like pieces of silicon are capable of generating electricity. How and why does this process take place? The principle, known as the photovoltaic effect, was discovered almost two centuries ago, in 1835. For this we have to thank a French physicist Alexandre Becquerel. However, it would be another 120 years until the invention of silicon-based solar panels at Bell Labs.
First it should be noted that a PV module is not a uniform structure, but rather it consists of many elements, usually from 60 to 144. These elements are called solar cells. In most cases they are made of silicon, but it could be any other semi-conductive material. This property simply refers to an ability to conserve electrical imbalance while not being entirely non-conductive.
So, how do solar panels work exactly? When the rays of the sun reach a solar cell, the collision with photons frees some electrons in the material. Now there is energy where there was none before. To create an electric field, a solar cell must have two layers – one with a positive charge and one with a negative. The field makes the freed electrons flow towards the edges of the cell, where the current is picked up by the metal plates and transmitted further via cables. There are a couple more stages required before this energy can actually be used to power your house. If you’re interested, we have an article that answers the ‘how do solar panels work’ question in much more detail.
What are solar panels made of?
It is safe to say that most solar panels nowadays are made of silicon. However, it wasn’t the first material to be used in this role. The first photovoltaic elements were made of selenium. Other semiconductors have similar properties and can also be employed in this fashion, but silicon has proved to be the most efficient and available material.
Not all silicon is equal: PV modules may have considerable efficiency differences depending on the kind of silicon that was used in the manufacturing process. The majority of existing solar modules may be grouped into two categories: those using monocrystalline cells and those that employ polycrystalline silicon. You can easily tell one type from another – polycrystalline panels are bluish in color, while monocrystalline modules tend to be black. More importantly, they also differ in price and efficiency:
- Polycrystalline panels are easier to manufacture, which makes them more affordable and less efficient, usually between 13 and 16%
- Monocrystalline cells are single crystals, while their cheaper counterparts are made from a block of silicon. This makes them more expensive, but allows for higher efficiency of up to 22%.
How does the weather affect solar power?
Weather dependence is the biggest, if not the only downside of solar generation. Despite huge progress, even the best solar panels will take a hit in cloudy weather or when overheated. But how big of a hit?
When it comes to high temperatures, the math is pretty straightforward. Find out the temperature coefficient of a panel (included in the data sheet) and you know how much you lose for every degree above 77°F. On average, this number is around 1% of the overall capacity.
It’s more complicated when it comes to quantifying the effect of clouds. Mainly, this is because we can’t measure the cloudiness of a day as precisely. If the day is only partly cloudy, it could mean both a slight decrease and even a brief increase in production. Some clouds act like a magnifying glass, concentrating the energy of the sun on your modules. However, they don’t occur as often as other kinds of clouds, so it will be more realistic to expect a loss in production between 10 and 25%.
On really overcast days when you can’t or only barely see the shadows of objects, your solar array will only generate 10 to 30% of its normal energy output. It might not be your biggest concern though: if the clouds come with heavy snow, a thick enough layer will completely block off the sun. The good news is that solar panels are actually very resistant to rain and very strong winds, so the snow and ice are the only things that you have to worry about.
How do solar panels work for your home?
The principle behind the light to electricity conversion should now be clear, but how do solar panels work for your home? What are the steps that will let you harness this power?
Put simply, you just need to find enough space on any surface with optimal sun exposure. In most cases, the roof is a good idea, although you can easily set up a ground-mounted array. The second step would be determining your energy needs and autonomy requirements. After that you can proceed to picking and purchasing the equipment. From then on, unless you want to perform the installation yourself, a professional contractor will handle all the work. This often includes the paperwork required for grid interconnection. This way you’ll be able to make extra profits selling the excess electricity to your utility.