How solar panels work: Quick guide with stages and schemes

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.

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.

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.

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.

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.