Investing in solar energy is a fantastic idea for you, your family and the planet, but it is a big commitment to make so you want to make sure you know exactly what you are getting and why.
In this blog we will take you through the different types of solar panels, how they work and which one is best for you.
But first …
What is Solar Energy?
That seems like a fairly daft question as we all know that Solar Energy comes from the sun, but what isn’t obvious is how it works and how we turn sunshine into electricity for our homes.
Solar has a very long history, much longer than you think in fact.
Talking energy from the Milky Way’s biggest star was first discovered in the 16th Century when Swiss Scientist Horace-Benedict de Saussure designed the first solar oven.
Fast forward to the early 20th Century and we find the 26 year old Albert Einstein publishing his work “On a Heuristic Viewpoint Concerning the Production and Transformation of Light.” in which he studied the ‘photoelectric effect’.
By the mid 50s companies were producing solar powered Telephones and Radios.
Now, we have many different Solar Power technologies to choose from.
The Different Types of Solar Panels.
Before we start our deep dive into commercially available panels we need to know a little about how the sun creates our power.
Light travels using something called protons. These tiny molecules whizz through the air, bouncing off surfaces and making it possible for us to see things.
A Photovoltaic cell contains various materials and semiconductors that react to those protons by getting agitated and vibrating – this creates energy and, through some chemical magic, electricity.
Most Solar Panels are made up of photovoltaic cells.
Polycrystalline solar panels
To simplify things a fair bit, photovoltaic cells are made up of tiny crystals of silicon bunched together to catch the protons and create that energy.
The manufacture of Polycrystalline solar panels means those crystals are fused together to create a cluster. This is a much quicker and easier method of manufacturing than other panels as silicon is simply poured out the frame and allowed to set.
Simple manufacturing means cheaper production cost but, unfortunately, also means they aren’t as efficient as some other panels.
The manufacturing process also means that these panels are more eco-friendly than monocrystalline solar panels, more on those later, as most of the silicon is utilised during production so less waste is produced.
Polycrystalline panels are generally used in solar farms, traffic lights and very large domestic installations.
You can identify a panel as being made up of polycrystalline cells as it will be blue.
Monocrystalline Solar Panels
Unlike Polycrystalline cells, the manufacture of monocrystalline cells requires each cell to consist of a single silicon crystal split into layers, so the process is much more wasteful, time consuming and expensive.
However, it also means that monocrystalline panels are a lot more efficient as the energy can travel through the silicon much more quickly.
Monocrystalline are generally used in rooftop, domestic installations as they take up less space than their polycrystalline counterparts … and they are always black.
Passivated Emitter and Rear Cell (PERC) Solar Panels
PERC Panels are a relatively new invention and were invented in 1983 by Australian scientist Martin Green and his team at the University of New South Wales.
The problem Martin was trying to solve was making monocrystalline panels more efficient then they already were. In a typical mono cell, the protons can fly straight through the silicon without exciting any atoms.
This meant trying to increase the number of protons making contact by adding materials to bounce them around inside the cell.
Using 2 ‘reflective’ layers at the back of the cell allowed the protons to be pinged back into the silicon and increase the efficiency of the panel to 23 – 24%.
It took decades to make this technology affordable for the market, which is why we are only just seeing PERC Panels being used in commercial settings.
Thin-film solar panels
We mention these just to ensure you know what is available on the market but these second generation panels wouldn’t be suitable for a domestic installation.
Instead of using silicon crystals to generate electricity, thin layers of photovoltaic material are placed on top of each other. These materials are either amorphous silicon, cadmium telluride, copper indium gallium selenide and organic PV cells.
This kind of panel works at about half the efficiency of other panels and has a shorter lifespan but is much more flexible and can be used in places where solid panels can’t.
Solar panel cell count
Cell counts only really apply to monocrystalline and polycrystalline panels as they are the ones that use cell arrays.
60 and 72 Cell Panels
These 2 sizes are the industry standard at the moment, coming in 10 cells by 6 or 12 cells by 6.
The larger size obviously produces the most electricity but both are equality efficient.
Going for a larger panel means you will need fewer pieces for your install but will need quite a big roof, whereas the 6 x 10 will fit nicely on most domestic roofs and you can add more panels.
108 Cell Panels
These are the GOAT of domestic solar panels coming in
The technology is slightly different as the arrays are made up of 54 cells that have been split in half. While this seems a little unscientific, it actually means there is less material for the charged electrons to travel through, lowering the resistance of the cell and increasing its efficiency.
Using this method, smaller panels can be used to create the same amount of energy
Other Cell Count Panels
- 32 Cells – Used for small battery charging
- 36 Cells – Used for larger battery charging such as those for cars and vans
- 48 Cells – Used for utilities such as trafficlights
- 108 Cells – a split cell 54 count panel, quite expensive
Which solar panels are best for domestic installations?
Monocrystalline panels are the best for a domestic installation. They are the most efficient for the price. While poly panels are rated at about 18%–22% efficiency, mono panels are racking up a whopping 24%.
If you are installing split Monocrystalline cell panels, ones with a cell count of 108, you will not only be getting more power, you’ll be getting more efficiency per panel. More efficiency means less panels too, so that makes monocrystalline systems the best for rooftop insulation.
Which are the best panels for commercial installations?
While the monocrystalline panels are more efficient, they are also more expensive.
So, there will come a point where having less efficient panels will become a cost effective solution and that usually depends on how much room you have.
Most solar farms, the ones you can see from the road as you pass, are constructed using polycrystalline panels due to their affordability.
Some commercial installations may also use thin-film panels if the area where they are being mounted is awkward or curved.
Which panels are the most efficient?
We have covered this a fair bit so far but we will just sum up the efficiencies of the different panels, with the split cell mono crystalline coming in top and the poor old thin-film foundering at the bottom.
Half Cell Monocrystalline – 20% – 24%
PERC – 17 to 19.5%
Monocrystalline – 16.5 to 19%
Polycrystalline – 13% and 16%
Thin-film – 7% and up to 18%
Best Panels for high and low temperature
Electricity moves faster at lower temperatures. This means, as the heat increases inside the photovoltaic cell so does its resistance leading to the panel becoming less efficient.
Polycrystalline solar panels have a higher temperature coefficient than monocrystalline panels. In layman’s terms that means the heat affects the efficiency more than it would in a monocrystalline panel.
So, once again, the mono panels perform better in extreme conditions, which is a moot point here in blight as even polycrystalline panels have an acceptable maximum temperature of 85 °C and a minimum temperature of -40 °C.
But, as the UK rarely sees temperatures this extreme, most solar panels function very well in our green and pleasant land.
What are the most durable solar panels?
This is another win for monocrystalline panels. The fact they use individual silicon crystals means they can stand more heat, more cold and more knocks.
That said, poly panels are pretty indestructible too. While there is more chance of damaging a silicon crystal as they are all fused together, you’d have to do some pretty serious damage to a panel to affect its efficiency.
Barring any serious accident, most solar panels will still be working at 80% of their full power even after 25 years.
| Type Of Panel | Power output | Cost | Efficiency | Flexibility |
|---|---|---|---|---|
| Polycrystalline | 260 Watts | Average £250 | 13% – 16% | None |
| Monocrystalline | 360 Watts | Average £250 – £300 | 20% | None |
| Half Cell Monocrystalline | 405 Watts | Average £100 – £200 | 24% | None |
| Thin Film | 200 Watts | £250 | 7% – 18% | Some |
Fire, hail and hurricane rating
Once again the ratings for most solar panels tend to be set to international standards.
Here in the UK we have no need to worry about enormous hailstones or 80 mph winds, so we are just interested in fire ratings.
Most panels, whether poly or monocrystalline, have a Class C Fire Rating which states the item is effective against light fire test exposure and the flame spread should not go beyond 4 metres. This is standard that applies to most building materials including plywood, fiber-board, and hardboard.
Panels used on solar farms and other large, outdoor settings would have a lower Class B fire rating.
