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In the last decade, solar has experienced an average annual growth rate of 33% globally, according to the Solar Energy Industries Association.
This unprecedented growth is by no means a fluke. Reduced costs of solar panels, government incentives, and increasing environmental awareness have led to increased adoption of solar as a source of energy to run many homes worldwide.
With these evident benefits, the question remains of whether solar energy savings are enough to offset the costs of traditional hydroelectricity. Indeed, there are multiple factors to consider before buying home solar panels. However, throughout the course of this article, we’ll dive deep into solar panels and their underworkings.
What are solar panels?
Solar panels also referred to as photovoltaic (PV) panels/modules are essentially devices designed to absorb the sun’s energy.
These panels are often placed on the roofs of houses to maximise the amount of sunlight they absorb throughout the day. Depending on the purpose, they are also placed on the ground in open spaces and on top of cars and other equipment.
What are solar panels made of?
Solar panels are made up of photovoltaic cells. The term photovoltaic is derived from two root words; ‘Photo’ and ‘volt.’
The former comes from the Greek word for ‘light’, and the latter is the unit of measurement of electric potential or electromotive force. Hence, ‘photovoltaic’ can either refer to the ability to produce electricity from light or to the process of producing electricity from sunlight.
Fundamentally, each PV cell consists of PV materials. Originally, the two commonly used PV materials were monocrystalline silicon and polycrystalline silicon. However, with time, new and better materials have come along and are being used to great effect to deliver more efficient and smaller PV cells.
For example, gallium arsenide, metal chalcogenides, organometallics, perovskite, amorphous silicon, and mesoscopic solar cells have all emerged as viable options and are increasingly becoming the materials of choice for modern solar panels.
In practice, PV cells maintain two layers sandwiching the PV materials. The top layer facing sunlight is an anti-reflective coating, while the bottom layer is a reflective layer.
PV materials are protected by these layers from the elements and other physical damage. They are mainly made from a combination of glass and/or plastics.
Each PV cell can vary in size from approximately half an inch to 4 inches across, producing only 1 or 2 Watts worth of electrical power. in fact, some types of panels, like thin-film PV cells, are built differently but with similar materials. However, we will touch on them later in the guide.
Image Credit: https://www.eia.gov/
How do solar panels work?
At a basic level, solar panels convert sunlight into usable energy (electricity). The sunlight hits the cells in the panel, creating an electric field. This electricity then flows to the edge of the panel, then into a conductive wire leading to an inverter for conversion to AC power for use in the house.
All this happens by utilising the photovoltaic effect, also called photo electricity. The photovoltaic effect describes the ability of matter to release electrons when exposed to light. PV cells are made of semi-conductive materials that can emit electrons when exposed to sunlight.
As a result, photons from the sun hit the semiconductor in a solar PV cell (typically designed carefully to maximise photon absorption), knocking loose electrons that drift freely throughout the cell.
This cell consists of positively and negatively charged semiconductors sandwiched to create an electric field, forcing the drifting electrons to flow toward conductive plates that line the cell.
Known as an energy current, this flow determines how much electricity each cell can produce, and once the electrons hit the metal plates, the current is then transmitted into wires. Thus, resulting in the electrons flowing like in any other source of electric generation.
How much electricity do solar panels produce?
Of all the features of a solar panel, the most noteworthy is how much energy it generates. Consumers should carefully weigh whether switching to solar is worth the effort before committing. And this question can be answered by determining how much energy roof-mounted panels can produce.
As well as whether solar can meet the long-term demands of a home or business that was once powered by other energy sources. To determine this, let’s ingest some basics, shall we?
Solar panels are rated in watts, and the SI unit is used to measure power production. In practice, most solar panels for residential properties produce between 250 and 400 Watts of electricity per day.
You can determine how much electricity a panel will produce in a day by using this formula.
Power x Average hours of direct sunlight = Daily Watt-hours (with power denoted in watts)
For example, if a 100W solar panel receives eight hours of sunlight daily, the total power output is then calculated by multiplying 100W x 8 = 800Wh or 0.8 kWh
Nonetheless, the amount of electricity a panel produces will vary depending on a number of factors. For example, the power rating, the number of hours of sunlight per day, the efficiency of the panel, how clean it is, etc.
So, when deciding the size and capacity of one’s sought solar system, it is best to put these factors into careful consideration, and aim for the upper limit to accommodate these variations.
Types of solar panels
Since we are now well-versed with how solar panels work and how much energy they produce, the next question is what type of solar panel one should choose.
Though the brands, styles and power ratings are numerous, you’ll be glad to know that only three types of solar panels are used in residential houses. These are namely, Monocrystalline, Polycrystalline and thin-film. These differ in design, materials and efficiency ratings.
Monocrystalline solar panels are named so because they are made from a single silicon. This single silicon is sliced from a pure, nontoxic and stable ingot to make a thin wafer. This industrial process consequently results in a highly efficient and eco-friendly product. Furthermore, they have a high-efficiency rate of 24%.
Polycrystalline panels are made from different silicon fragments, which are melted and poured into a mould. The fact that they aren’t made from pure silicon means less efficiency. They are also cheaper than monocrystalline panels.
Thin-film panels are a newer type of panel. They are less efficient and therefore require a lot more space. As such, they are used primarily for large industrial installations where space is not an issue.
Thin-film panels are the sleekest among the three-panel types. Because they are entirely black, flat, and flexible in shape and size. As a result, they are easy to integrate onto a home’s roof and do not require scaffolding, unlike monocrystalline and polycrystalline panels. Because of their low efficiency, one would need a significant number of them—to generate enough power to run a home.
Also read our articles on:
Monocrystalline vs Polycrystalline solar panels
How to install solar panels?
Solar power generates clean and eco-friendly energy without having any significant environmental impact. There are factors to consider, however, before you embark on your installation journey.
- The condition of your roof
- The slope of your roof
- The shape of your roof
- Weight capacity of your roof
- Power requirements
For a step by step process, read our article on solar panel installation.
How long do solar panels last?
Longevity is a crucial factor in choosing what type of solar panel—let alone choosing to go the solar direction at all. PV panels generally last over ten years, but the actual lifespan differs depending on the technology used to build them.
Monocrystalline panels will survive the longest, with an average life span of 25 to 40 years. Polycrystalline come in close second with an average life span of 25 to 35 years. Finally, thin film, which lasts between 10 and 20 years.
How efficient are solar panels?
Solar panel efficiency refers to the amount of sunlight or radiation that falls on the solar panel that it is able to convert into electricity. It is based on the ratio of energy generated by the solar cell and the energy input from the sun.
The formula for calculating efficiency is
Voc is the open-circuit voltage;
Isc is the short-circuit current;
FF is the fill factor and
η is the efficiency.
Read: How to calculate solar cell efficiency?
The higher end of efficiency with regards to solar panels today is about 22% to 24% efficiency. This means a low percentage figure like that shouldn’t scare you off as a highly inefficient figure. However, anything above 20% is good by the 2022 standards for solar panels.
Generally, multiple factors affect solar panel efficiency. The first one is the type of solar panel.
- Monocystalline panels usually have an efficiency of over 20%
- Polycrystalline solar panels have an efficiency of between 15% and 17%
- Thin-Film solar panels are less efficient, with a range from 7% to about 18%
Other factors include;
- Temperature: Warmer temperatures that negatively impact the efficiency of the panels. For context, amorphous cells decay by about 0.25% per degree of temperature increase over 25° C. On the other hand, crystalline cells decay by about 0.4-0.5%.
- Panel orientation: To maximise efficiency, solar panels need to be oriented directly towards the sun. In practice, photovoltaic panels’ performance is determined by their orientation and inclination, which influences the amount of producible energy.
- Shading: Solar panels work best when the entire panel is exposed to sunlight. Sometimes, clouds, trees or buildings might block part or all of the panel from receiving direct sunlight. This will negatively affect the efficiency of the panel.
- Maintenance: Even though solar panels can last 20 to 30 years, they are susceptible to a build-up of dust, leaves and other objects that can impede the reception of direct sunlight. They, therefore, need to be checked regularly.
Generally, solar panel efficiency can be increased with some practices. For example, having a professional install the panels, regular maintenance, using a solar concentrator, etc.
Environmental benefits of solar panels
There are basically two reasons why you would want a solar panel at your home or your business. Financial and environmental reasons.
In this section, we’ll look at the environmental benefits of switching to solar power.
- Solar panels reduce dependency on other forms of energy. Most energy sources, like fossil fuels, are bad for the environment and are finite. Solar mitigates this by replacing them.
- Solar energy is infinite and doesn’t pollute the environment during operation, and can reduce your carbon footprint by up to 80%.
- Solar panels last a long time and require little to no maintenance. This is good news because you shouldn’t have to replace your solar panels for a long time.
Which solar panels are best for home use?
Solar energy for homes has grown in popularity over the last decade. In regions with irregular grid power supply, they have filled the gap. And in other regions, they continue to save the users loads of money, not to mention the environmental impact.
Our recommendations for panel choices are grouped into types, sizes and locations.
Monocrystalline panels are our number one choice for home use. They require less space, are more efficient than the other types and have a longer life span. They are, therefore, perfect for home use.
Their only downside is that they are more expensive than the others. Polycrystalline panels can also work in a home setting but are not as efficient as monocrystalline ones.
Rooftop solar panels are our pick of the bunch for home use. This is because the space on the roof is seldom used for anything, and so having solar panels on there will not take space away from other uses as opposed to panels mounted on the ground.
The larger the surface area covered by panels, the more electricity you will generate. This simple logic suggests that you buy as many panels as you can afford, and that can fit in your allocated space to maximise energy generation. In many countries, the extra power can be sent to the grid, thus earning you something extra via net metering.
Read: Benefits of residential solar panels
New inventions in solar panels
Research and development in solar technology has steadily grown over the years by leaps and bounds. These have gone far beyond the good old solar panel on your roof or solar farms out in the desert.
Several exciting new solar panel technologies are either in the production pipeline or already on the market. These revolutionary technologies will change the way we think about energy production in general as well as solar in particular. Solar no longer requires large amounts of roof space, nor does it need to look dull.
- Floating solar farms
Floating photovoltaic farms, also known as ‘floatovoltaics’, can produce massive amounts of electricity without using expensive land or real estate. They are less expensive to install than land-based photovoltaic panels. This is because they are always floating and can also help with water management by producing large amounts of clean solar power.
Existing research suggests that floating solar panels have the potential to generate more electricity than land-based panels because of the cooling effect of water. By reducing air circulation and blocking sunlight, they minimise the loss of water to evaporation.
In addition, floating solar panels are able to mitigate noxious algae growth and, as a result, reduce water treatment costs. Additionally, the water beneath keeps solar panels clean and helps minimise energy waste.
- Solar Skins
This is novel photovoltaic technology. Solar skins have custom designs embedded in the PV panels to look invisible. Sistine, the manufacturer of solar skins, is testing the technology at the United States National Renewable Energy Laboratory to boost its performance.
Because of selective light filtration advancements, solar thin-film skins maintain a high level of performance. The sunlight that falls on solar skins is filtered so that it can reach the solar cells beneath it, resulting in an image that is displayed at the same time as providing solar energy.
- Building-integrated photovoltaics
These blend into the building’s architecture. They might take the form of roofs, walls and facades. These replace the existing parts of the building, like the roof or walls and can help save money in the form of the costs of what is being replaced.
FAQ on solar panels
Are residential solar panels worth it?
In a nutshell, residential solar panels are worth a shot. They save one money on their energy bills, reduce your carbon footprint, could earn you tax credits, and boost your home’s value.
Read more on the benefits of residential solar panels here.
How much do solar panels cost?
The cost of solar panels actually depends on a number of factors. The type of panel, the size of the panel and the manufacturer. Monocrystalline panels cost more than polycrystalline ones, which cost more than Thin-Film panels.
It also goes without saying that larger panels often cost more than smaller ones. Regarding brands, well-known brands like LG and Sungrow make high-quality panels, and are more expensive than most.
On average, monocrystalline solar panels cost $1 to $1.50 per watt, polycrystalline solar panels cost $0.90 to $1 per watt, and thin-film solar panels cost between $1 and $1.50 per watt.
How many solar panels do I need?
The number of solar panels you need depend on your energy requirements. For example, for a 6kW energy system, you will need 19 solar panels. If your power requirements are lower, you will need fewer panels.
How to clean solar panels?
There are no hard or fast rules when it comes to cleaning solar panels. Different manufacturers often have different cleaning guidelines. The type of dirt will also inform the method to be used.
Read more about cleaning solar panels here.
What are the best solar panels?
In terms of efficiency, monocrystalline solar panels are the best, even though polycrystalline ones are cheaper. It all depends on your priorities as a buyer.
Is my home suitable for solar panels?
The suitability of your home for solar panels is determined by calculating the solar energy potential of your house called the sun number score. It is a rating between zero to one hundred. Zero is the lowest, and a hundred is the highest number on this solar number scale.
Learn how to calculate the sun score of your building here!
Where to install solar panels?
There are two places in your home where the panels can be installed. The roof and the ground. The factors informing the decision on where will be the size of the area and exposure to sunlight.
Can I install solar panels myself?
We advise that DIY installation be a last resort option. It is best to use a professional to install solar panels in your home. This will help maximise the efficiency of the panels and reduce overall future costs.
How to maintain solar panels for the long term?
Solar panels scarcely need maintenance in their 20 to 30-year lifespan. But since they are located outside the house, they might collect dust, leaves, and grime.
Read more on solar panels maintenance here!
Is it worth buying used solar panels?
There is a thriving market for used solar panels all over the world. Used panels cost less than new ones hence their popularity. There are, however, some risks as you might find the panels damaged. But, with the right precautions, you could get yourself good deals on used solar panels.
Read this buyer’s guide to used solar panels for more information.
Overall, solar energy is a great alternative to the more commonly used forms of energy. It is cheaper in the long run, cleaner and mostly outage free. The pros definitely outweigh the cons when it comes to solar as a choice of energy source for your house.