Solar panels

How solar panels work: Quick guide with stages and schemes

Solar industry in the US is expected to grow by 400% in the next decade: from 20 GW of solar power that are installed annually we’ll move to 80 GW per year in 2030. Since solar is going to be a hot topic for a long time, here’s a quick guide on how solar panels work. You’ll find answers to the most basic questions about solar and hopefully it will help you impress friends and colleagues with your knowledge when the time calls for it.

Solar energy gets to your home appliances just in 3 steps

grid tied system
Let’s start from the very basics: solar panels and how they work. The whole solar industry is about the photovoltaic effect. It all started in 1940 when Richard Ohl discovered that you can create electricity by illuminating silicon. When sunlight hits solar silicon cells, it sets electrons in motion which results in direct current (DC) inside a solar panel.

Direct current by itself can not be used for our daily needs, which is why an inverter is an important part of a home solar installation. It turns direct current to alternating (AC) and sends it either to our appliances or into the commercial grid.

Solar generation process can be described just in three steps:
  1. Sunlight hits solar panels which are essentially silicon cells encapsulated in glass and an aluminum frame. Cells produce direct current – DC.
  2. DC flows from the module through the wires to the inverter and/or the battery. The batteries usually need direct current for charging. The inverter turns direct current into alternating – AC.
  3. The inverter sends AC to the electric panel (breaker box) of the house to power home appliances. You can also send the energy into the commercial grid, which causes your electrical meter to run back. This allows you to earn credits and offset your energy bills.

The Sun sleeps at night, so do solar panels

It’s only logical: how does a solar panel work when there is no sunlight?If the moon is bright, it can be strong enough to cause the photovoltaic effect to occur, but you can’t expect too much power from it. Maybe it will be enough to power the lamp on your nightstand but hardly any more than this.

This is the reason why in an off-grid system – when you aren’t connected to the grid – it is mandatory to have an energy storage. With batteries you can run any appliance in your house at night powering it with the energy you collected during the day.

What happens to solar panels when it’s cloudy or raining?

Schemes - how solar panels work
Some believe that panels become absolutely powerless when the sun is blocked by a small cloud. In reality it is not so. Of course, when irradiance levels drop, it affects how a solar panel works. While clouds do block some of the solar radiation that is visible to an eye, other types of radiation can still go through and successfully land on panels.

In practice, bad weather decreases the production of a PV array no more than 40%. The impact of clouds have decreased even further in the last years with the implementation of modern technologies. Some panels are designed to be especially resistant to bad weather, like Canadian Solar PV modules.

Harsh weather and even natural disasters usually don’t pose any threat to solar panels. Solar cells are protected by a layer of tempered glass and the aluminum frame is also quite sturdy. Panels are made so durable that they can withstand 140 mph wind speeds at the very least. What you really don’t want for your system is to be shaded. Even a small shade on a corner of one panel can in theory bring the output of the whole string down by more than a half.

How do solar panels work in the winter

Why may solar panels not work
Strange as it may seem, solar panels do best when it’s cold and sunny, whereas high temperatures lower their production. The only problem with winter is that there is naturally less sunlight, so your system is going to produce around 50% less energy than in the summer. This is, however, offset by one important advantage of snow – it reflects the sun radiation to your panels. In other words, snow raises the albedo of a surface and you get more solar energy in winter months.

Snow itself isn’t a big thing to worry about. What’s more, clearing panels from snow with a shovel is not recommended – you might damage the modules. Solar panels are able to cope with snow loads without your help for several reasons.
  • Almost all solar panels are installed at an angle. The tilt helps snow slide off the modules once the heap is heavy enough. The only place you would want them flat is at the equator where snow is not a problem at all.
  • Solar panels heat up while working. Besides, they are dark and attract heat. Snow melts, slides down and even cleans your panels in the process.

Benefits of solar panels outweigh disadvantages

So what are the reasons behind solar panels being so popular today? Advantages of solar panels include:

  • Green energy for sustainable development. The world tries hard to decrease greenhouse emissions. Solar energy is one the biggest hopes of humanity to stop global warming as solar panels don't release harmful gasses into the environment.
  • Reliable source of energy in all circumstances. Panels work all day long and aren’t afraid of harsh weather or natural disasters. They don’t need fuel, they make no smell or sound and their lifespan exceeds 25 years.
  • Smart long-term investment that offsets your energy expenses. On average, solar panels allow you to decrease your monthly electricity bill by $100. In some cases you stop paying for energy at all. In the US, solar panels generally pay for themselves in 6-8 years, depending on the area. Everything after that is profit. What is more, a solar system increases the value of your property and prolongs the lifespan of your roof.

It’s a lot, as you can see. What are the possible cons? When it comes to disadvantages of solar panels, you could probably mention:

  • Legal constraints. There is no single federal policy about the status of solar panels and prescriptions about their installation. In some states, like Florida, it is perfectly legal to install panels without any papers. In other areas you would need a solar permit. Find out how easy it is to go solar in your state here.
  • Installation and dismantling. Solar panels take some time to be installed and it’s difficult to remove them once the setup is complete. If you decide to move out, it’s more reasonable to sell the house with the solar system instead of detaching the panels from the roof and trying to install them in a new place.
  • The upfront costs might seem quite high. A small 5 kW solar system in the US may cost over $13,000. However, some states have special programs and incentives that allow you to decrease your expenses. Of course, you should make use of the Federal Solar Tax Credit program that currently allows you to return 22% of installation costs.

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Why may solar panels not work?

In situations where your panels don’t produce any power, PV modules themselves are rarely at fault. Reliable manufacturers test every module before shipping. Even if the module was damaged during transportation, its performance may decrease, but the ability to produce electricity shouldn’t disappear completely. That is why under no circumstances should you try to dismantle a solar panel to see what’s inside – you’ll just end up with a broken module.

The most problematic place is usually the connectors. Make sure they are fixed tightly following the instructions in the installation manual. Also check if the positive terminal of the panel goes to the positive one of the inverter and so on. If you can’t figure out the problem, find someone who knows how does solar panels work: invite a certified electrician to take a look at your system.

If your solar panels are already installed, but the performance starts to decrease, the simplest thing you can do is to wash them. It’s a lot like washing windows – just don’t use soap and try not to scratch the surface of your panels. Regular cleanup, as well as visual inspections and checkups by an electrician are recommended to prolong the lifespan of your system.
Illustrations – Marina Fionova

Read Also

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