Solar panels come in all sorts of shapes and sizes. Some are used to produce grid-level energy production, some are installed on domestic rooves and some exist to stop your calculator from running out of battery.
Although each of these is unique, this article is going to break down the different types of domestic rooftop solar panels and how the technology compares.
There are essentially two primary types of solar panel that you need to worry about. These are monocrystalline and polycrystalline.
Both types of solar panel are made via essentially the same process, except that the mono silicon used in monocrystalline panels requires an additional stage of processing, creating a higher purity finished product.
Whereas polycrystalline is created from lots of small crystals, monocrystaline uses one large crystal.
What this means is, monocrystaline panels are more efficient, but polycrystalline panels are cheaper to produce. At least, this was the case, up until recent developments changed the picture.
Due to technological improvements and the general decrease in the cost of solar panels, moncrystaline panels have now become the dominant form of solar technology with polycrystalline effectively becoming obsolete.
The types of panels available to choose from now, essentially, come down to variations of the mono silicon design.
But which is the best type of panel to go for?
Half cut panels take the standard monocrystaline design and cut the panel into two parts. This technique allows two separate paths for electrons to flow, reducing the impact of shading or damage on either half of the panel.
Where as other designs might experience significant drops in efficiency, half-cut panels will maintain up to 50% more efficiency and output 1-3% more power.
This makes them a good option if you’re expecting your solar panels to experience some shading during the day.
Most half-cut panels also make use of PERC cell technology helping to further increase efficiency.
PERC cells or Passivated Emitter and Rear Contact solar cells are a type of solar technology that makes use of an additional layer that reflects unused light back into the cell.
These panels are able to produce 6-12% higher output efficiency compared to traditional mono cells. They also cope better in lower light or shaded conditons due to their ability to recapture lost light using that additional layer.
This type of cell deesign combines crystalline silicon cells with a thin film layer of amorphous silicon.
This benefits the solar panel by producing higher efficiency, a better temperature coefficient - which means better performance under high temperatures - and an improved aesthetics.
Rather than having the white crisscross lines, HJT has an unbroken black finish which blends more easily on a rooftop.
A brand example would be the REC Alpha Pure panels.
N-type solar panels are similar to PERC cells, but where the P-type uses boron the N-type uses phosphorus. This makes N-type panels more resistant to degradation and are able to produce higher efficiencies. They also perform better in low light, than other models.
Another important characteristic of these types of panels is that they are bifacial. This means they are able to generate electricity from either side of the panel. This makes them a good option as ground-mounted panels where they can make use of reflected light on both sides.
To find this technology, have a look at the Q Cells Q.Tron solar panels.
When it comes to picking the right solar panels there are 5 factors you need to consider.
These are the following:
Each of these factors should play an important part in which panel you decide to go with.
Depending on where you are planning on getting your panel fitted, the conditions the panel will be exposed to and your overall budget will affect how much attention you give to each of these factors.
When talking about solar efficiency this refers to the amount of electricity produced in proportion to the volume of sunlight that directly hits the solar panel.
Even the most efficient solar panels will lose some energy. This occurs through heat loss, via reflection or due to sunlight passing through the cell rather than it getting captured and converted.
The efficiency rating refers to the percentage of solar energy that is converted to electricity.
A standard efficiency rating is usually between x and y%, anything above this is considered to be highly efficient.
Solar panels don’t operate at 100% of their initial efficiency for the full duration of their lifespan. As they age their efficiency will decrease at a certain rate. This rate of decline is known as the degradation rate.
A standard degradation rate is around 0.5% per year. This means if a solar panel has an efficiency of 21% it will operate at 20.9% in year one, 20.8% in year two and 20.5% in five years time.
Premium solar panels tend to degrade at around 0.25% per year meaning over the course of it’s lifetime a premium panel will maintain its efficiency far longer.
The temperature coefficient refers to how well a solar panel performs at temperatures above its ideal temperature.
Most solar panels operate best at around 25 degrees Celsius (77°F) and will lose a small percentage of their performance if this is exceeded.
This is important if your panels are going to be installed in regions where the temperature regularly exceeds 25°.
You are probably familiar with the concept of a warranty but all solar panel manufacturers will provide a standard warranty on purchase.
Within this warranty typically you will find a product warranty which covers defects in materials or workmanship and a performance warranty which guarantees a certain level of energy output over time.
Sometimes additional warranties are also offered by solar installers on top of the manufacturer’s warranty.
Typical product guarantees last around 10 to 15 years, while performance guarantees tend to be longer, around 25 years.
At the top end of the market, you can find 30-year performance guarantees. However, do be careful as in recent years there are a number of solar manufacturers that have experienced financial issues. A warranty is only as good as the company that offers it.
Solar technology is developing quickly with new designs and innovations making it difficult to keep up with what’s available on the market.
When choosing what type of solar panel is the best for you, you need to talk to your installer and work out the exact requirements for your property.
Are you looking for a rooftop installation or ground-mounted panels? What is the shading like in your location and is your roof south-facing?
Having an idea of what is available on the market and what questions you need to ask when choosing your panels will allow you to ensure you find the best fit for you.
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