Many solar hopefuls set off on their solar journey knowing little to nothing about how solar panels actually work.
However, it’s nigh on guaranteed that new solar customers will ask this seemingly obvious question: How do solar panels work?
And why wouldn’t we ask? When you think about it, it’s pretty amazing that a funny looking window-glass-thingy that sits atop our roof can turn the sun’s rays into very useful and very clean electricity.
You don’t really need to know how they work in order to exploit their benefits. However, a good grip on solar panels and solar system basics can be highly beneficial for several reasons.
Firstly, understanding how solar panels work is very useful when researching your first solar system.
Secondly, solar quote negotiations are much more effective with a basic understanding of solar lingo and language. Armed with solar basics, you’re better placed to make informed decisions, ensuring you purchase a system that’s right for you.
Thirdly, understanding how solar panels work allows you to extract every ounce of performance from your system. This can save you a heap of cash, and further reduce your carbon footprint.
And fourth, should panel performance waver, or a problem arise, you have a better chance relating problems to technicians. You may even save cash by deciding that you don’t actually need a technician.
A further benefit is gained by being able to understand developments in solar technology. Knowing how a solar panel works allows you to assess new technologies and their potential for integration to your system.
In the following paragraphs we’re going to go explain how solar panels work, step by step. No, you don’t need to be a scientist or an electrical engineer. This explanation is all about keeping it simple.
Let’s go solar…
The sun produces unimaginably small bundles of energy called photons. Calling a photon a bundle of energy is essentially correct, yet horribly inadequate.
However, for the purpose of this explanation, and our sanity, calling a photon a bundle of energy is sufficient for the task at hand. It’s the photons produced by the sun that our solar panels convert into electricity.
A solar panel is made up of a number of components. The most important component is the solar cell. You may have seen a close up of a solar panel, noticing a series of disc like (usually square) structures arranged symmetrically.
It’s the solar cells that collect photons from the sun. Solar cells are the primary operative part of the solar panel and the most critical panel component.
Not only do they collect the photons, but they also convert them to DC, or direct current electricity (more on DC later). Of all the sun a solar cell collects, about 15% to 22% will be converted to electricity. The electricity produced by solar cells is called photovoltaic energy.
There are 3 types of solar cells:
All of the solar cells in a panel are connected to each other via wire. They meet at a junction box on the back of the panel. Here they can be connected to other solar panels to form a string. A “string” is simply any number of solar panels joined together.
The solar cells are sandwiched by a glass front and plastic rear panel. Between these are layers of insulation. These are all held together by a metal frame, most likely aluminium. One solar panel is roughly 1 meter by 1.7 meters.
The insulation is very important. Solar panels under perform when subject to excessive heat. Obviously, this is a problem, as full sun exposure is required to ensure maximum solar cell efficiency.
This conflict is indeed difficult to overcome. It is often recommended that solar consumers in very hot climates purchase panels with a high level of heat resistance.
Depending on efficiency, one solar panel will generate 250 to 360 watts of electricity when working at peak capacity.
That’s enough electricity to run a number of laptops, or a blender, shaver, or stereo, for example. Keep in mind that’s only when running at optimum performance.
Solar panels are not always running at optimum output. Shade, clouds, and low sun intensity, such as morning sun, have an adverse impact on panel performance.
This is why you see many solar panels on a roof. They are all linked together via a cable to form a big system called an array. The array provides a large surface area to maximise sun catchment which is solar conversion potential. There’s power in numbers, so to speak.
While you will see the odd roof with 4, 6 or 12 panels, the most common number of panels is around 22 to 26 panels. An array of this size is enough to power the average Australian home in which 4 to 6 people reside. This depends, of course, on geographical conditions, and household electricity usage.
There are two types of electrical current. AC which is alternating current, and DC which is direct current.
All of the appliances in your home run on alternating current. Your solar panels, however, generate direct current.
So, in order to use the electricity your solar panels generate, we need to convert the direct current to alternating current.
This is done via a device called an inverter. The inverter acts like the brains of your solar system. It is by far the most complex component of any solar system.
There are two common types of inverter: a string inverter, and a micro inverter. The most common and affordable is the string inverter.
The string inverter is about the size of an instant hot water system and is mounted in a cool, dry place somewhere in your home. Garages are a common location.
With a string inverter, DC current travels from your solar array to the location of your inverter.
An important safety feature of string inverters is the isolation switch that connects the panel to the cable which carries the DC current.” This important safety device ensures volatile DC current is cut off at the source should a problem arise.
The other common type of inverter is called a micro inverter. A micro inverter is generally considered safer and more efficient.
With a micro inverter there is an inverter on the back of every panel. This means there is no cable carrying direct current to a single inverter placed away from the array.
The benefit of a micro inverter can be compelling to many – here’s why: in a solar array with a string inverter, each panel will run at the same output as the weakest panel.
Say, for example, one of the panels in your array is shaded by a tree and is only working to 30% capacity. This means that all of the other panels will only work to 30% capacity.
A micro inverter system avoids this issue. With a micro inverter, only the compromised panel will under perform. The rest will work independently and to the extent that conditions and capacity allows.
Whenever the sun shines, your solar panels are converting the sun’s photons to DC electricity. This DC electricity is being fed to the inverter where it is converted to AC power with which you can run your appliances.
At night time your panels are dormant. Solar panels need the sun to generate electricity. When it’s cloudy or overcast your solar panels will produce much less electricity. Exactly how much is relative to the level of cloud cover or reduced sunlight, and the quality of your panels.
As well, shade will impact the efficiency of your panels. If panels are shaded by a tree or an adjoining property, they will produce less electricity.
Of course, sun intensity is seasonal. So is the length of day and temperature. Very hot days will have an adverse impact on efficiency, as will the shorter days close to the winter solstice.
Your geographical location and the orientation of your home will also impact panel efficiency. Some locations are far better than others. Homes with a roof that has a northern orientation will see greater panel efficiency.
There are many variables that will impact the amount of electricity you can generate via solar panels. However, modern solar techniques and panel options are available to ensure solar systems are viable and cost effective – even in the most solar-challenged areas.
The vast majority of solar homes remain connected to the electricity grid. This means they take power from the electricity network and power station. The power station and the wires that bring electricity to your home is referred to as the grid.
If a solar system does not incorporate a solar battery, power must be taken from the grid in the evenings and at times of low sunlight. Whenever you don’t have enough sun to generate the solar power you need, grid power will take over.
You may even find yourself in a situation when you generate more solar power than you can use. In this case, this excess power is fed into the electricity grid. Your system, in fact, becomes a mini power station, sharing your excess electricity with other electricity consumers.
You will receive a small payment from your electricity retailer for the electricity you feed into the grid. It’s called a feed in tariff.
For those who choose to install a solar battery, there can be significant benefits. For example, during the day when everybody is at work and school, household electricity demand is at its lowest.
In this case, the unused electricity being generated by your panels can be directed to charging your solar battery.
This stored power can be used in the evenings when the solar panels are lying dormant. With enough stored electricity, there’s no need to take power from the grid. You will effectively be running your house by battery.
Yes, running your house with a battery is as awesome as it sounds. Solar batteries are expensive, however.
A solar system does not require a battery to operate. It’s an optional extra. If the battery price is a little steep to add to your initial solar system purchase, don’t worry, you can purchase a battery-ready system and install a battery later.
Many prospective solar customers believe that their solar system will protect them from blackouts. Well, yes and no.
A standard solar system WILL NOT protect you from a blackout. As most solar systems work in concert with the electricity grid, they remain subject to grid malfunctions and blackouts. If the mains power goes down, yours will too.
Even a solar battery will not protect you. Here’s why. Remember earlier we mentioned that your home’s solar system is a mini power station? During a blackout, your solar system may well continue to supply electricity to the grid.
This creates a significant risk for technicians trying to repair the cause of the blackout. Technicians cannot effectively isolate electricity supply to the grid in order to repair things such as fallen power lines.
However, for those interested in being able to power-on during a blackout, devices can be installed that allow your solar system to remain operational. In effect, it is possible to isolate your system from the grid to protect yourself from blackouts.
Of course, for the pioneers out there, you can use a solar system to go completely independent and off-grid.
The overwhelming majority of solar homes remain connected to the electricity grid. You have all the benefits of solar whilst enjoying the peace of mind of grid supply when the sun is not shining.
You can also be completely disconnected from this in certain circumstances, wholly relying on your own means of energy generation through solar. This means that a dwelling has no connection to the electricity grid. These homes function via solar energy alone. In these circumstances a solar battery is nigh on essential.
Off-grid solar is usually chosen (or required) by people who are geographically isolated from the main electricity grid. It is also chosen by those who wish to have complete electricity independence.
Generally speaking, the principals of an off-grid system are the same as standard grid connected systems.
However, a solar battery, and a more sophisticated solar system might be required to ensure off-grid solar homes enjoy reliable and constant electricity. Some off-grid homes will have back-ups such as diesel-powered generators.
In order to manage electricity, understand supply demands, generation, and usage, electricity is measured.
You may well be familiar with the terms of watt, kilowatt, and kilowatt hour. Having a good grasp of these terms is highly beneficial. It helps you understand how much electricity you use, how much retailers charge, and the size of the solar system you need to cover your usage.
Let’s define these three key terms.
Watt (W)- A Watt is the basic measurement of power
Kilowatt (kW)- A kilowatt is 1,000 watts or 1,000 units of power
Kilowatt Hour (kWh)- Kilowatt and kilowatt hour are frequently confused.
For solar consumers, and electricity consumers generally, kilowatt hour is the most important measurement. A kilowatt hour is a measure of energy used or produced over 60 minutes. If you look at your electricity bill, you can see the figures and a diagram of how many kilowatt hours you used during the last billing period.
The most important measurement for electricity consumers is the kilowatt hour. This allows us to fully assess our usage and our electricity bills. Follow this link to a useful video that will help explain kilowatt hour.
Solar system sizes are expressed in kilowatts. To determine the solar system size, you will need to tell the solar retailer how many kilowatt hours your household uses on average. This information is contained in your electricity bill, as stated earlier.
On average, families will use between 5,000 and 15,000 kWh of electricity per year. Check your electricity bill, and see where you sit relative to these averages.
In short, the sun shines on your solar panels, the solar cells contained in the panels capture the sun and convert the sun’s photons to DC electricity. DC electricity is sent to an inverter where it is converted to the AC electricity, which your home appliances require to run.
It’s fair to say that powering your home from the sun lends to more active involvement in your electricity management.
That’s not to say it’s any more complex or time consuming than the traditional grid sourced electricity we’re used to. On the contrary, generating your own power via solar is actually pretty simple.
Having a solar system teaches us more about electricity consumption. What’s more, they’re pretty easy lessons we can learn on the go.
It’s this solar knowledge that allows us to maximise the potential of our rooftop solar system, ensuring we maximise savings, and reduce our impact on the environment.