Solar Panels – Choose Your Technology!

If you are looking for a solar power system, the major part of that system is going to be “solar PV (photovoltaic) panels” (which I’ll just refer to as “solar panels” from here on) that convert sunlight into electricity using a phenomenon called the photovoltaic effect.

There are 3 major types of solar PV technology.

1. Monocrystalline
3. Thin Film

Only the first two technologies – monocrystalline and polycrystalline – are available in Australia these days. Thin film is no longer used here for residential installations.

The following are some details on each type of technology, including thin film just for general interest purposes:

1. Monocrystalline Solar Panels

Some think of monocrystalline solar panels as the ‘Rolls Royce’ of solar PV technology and the best choice. Monocrystalline is one of the oldest technologies, and more expensive to make, but this type have the highest efficiency.

These panels can typically achieve 15-20% conversion efficiency in the real world, i.e. convert 16-21% of the sunlight that hits them into electricity. They are made from wine-bottle sized single crystals of ultra-pure silicon and sliced up like salami to make individual wafers.

These circular wafers have their sides cut square, and are then converted into a monocrystalline “solar cell” that looks like this:

A Monocrystalline Solar Cell

The silver lines are wires that collect the electricity that is created when light hits the cell. The solar panel is made up of a matrix of these moncrystalline solar cells laid flat – like tiles on your bathroom floor:

monocrystalline solar PV panel

Monocrystalline solar cells are generally high performance, but because they waste a bit of space between the cells when they are encapsulated in a solar PV panel (the little white diamonds in the picture above) they perform about the same (in efficiency and power terms) as polycrystalline.

Some manufacturers use special techniques to make ultra high performance monocrystalline solar PV modules, such as “back surface fields”, “laser grooving” and hybrid technologies. These super high performance mono panels get efficiencies of over 20% – which is amazing. But you do pay about 30% more compared to conventional monocrystalline solar panels.

The easy way to spot mono solar panels on a roof is to look for the tell tale white diamonds between the cells.

(Top tip for keeping the kids busy in the car: Play “spot the solar panel” with bonus points for identifying the technology type! Yes I really do make my long-suffering kids play that game…)

monocrystalline solar pv array

2. Polycrystalline Solar Panels (Also Called Multicrystalline)

Polycrystalline solar panels are also made from silicon, but the type of silicon used is slightly less pure and they are cast into blocks rather than sawn from a single crystal. The fact that the crystals are randomly arranged means that they are visible individually.

Once the polycrystalline ingot is cast, it is sawn into square blocks and then sliced into square wafers that are processed to convert them into solar cells.

Here’s a close up of a polycrystalline solar cell – you can see that it looks very different to the sleek, uniform appearance of its monocrystalline rival:

Polycrystalline Solar Cell

Polycrystalline solar cells are very similar to monocrystalline in performance and degradation, except in multicrystalline, the resulting cells are typically slightly less efficient. However, as you can see here, there is no wasted space between the corners of the perfectly square cells:

Polycrystalline Solar pv Panel

This means that when they are encapsulated in solar PV panels, there is slightly more area available to absorb sunlight. The result is that a polycrystalline solar panel’s performance is almost identical to monocrystalline solar panels. Here’s what they’ll look like on your roof:

polycrystalline solar pv array

3. Thin Film Solar Panels

Whereas mono and polycrystalline solar panels are made in very similar ways, thin film solar panels use a completely different method of manufacturing. Instead of creating solar cells by sawing up large blocks of silicon, a film containing silicon is “sprayed” on to the surface that is to become a solar panel.

Although these processes have been around for a while, the modern variations of the thin film manufacturing process are a newer technology, so I have previously argued a modern thin film solar PV panel’s 20 year performance can only be estimated.

The production processes are generally more energy efficient than any of the other solar PV panel types, so they take less energy to manufacture than the mono or poly crystalline panels for the same rated power.

Thin Film Solar Panel Efficiency

Although it is improving, thin film solar panels are typically 8-10% efficient. This means they are around twice the size of mono or polycrystalline for the same power, and much heavier, so you need a big, strong roof and big, strong installers!

Thin film solar panels can also degrade by up to 20% in the first year on a roof before settling down to their specified power output.

You can usually spot thin film solar panels because don’t have the matrix pattern of the crystalline panels, they are just one uniform colour, usually blue, black or brown. The other thing that gives them away is that the arrays are usually huge to make up for their low efficiency. Here’s a roof near me that has a 2 solar arrays on it. Thin film on the left and monocrystalline on the right. The thin film array only produces about 20% more than the mono array despite being about 300% larger!

A roof with both mono and thin film solar panels

So to sum up, which solar panels are best type in terms of technology?

When choosing between monocrystalline vs polycrystalline solar panels, despite what many salespeople will tell you, there is nothing really to distinguish between the types – except their looks!

Thin-film was slightly cheaper per kW, but occupied at least twice the area, and no-one is 100% sure how much they will degrade in the long term. However, as mentioned thin film panels are no longer available for the Australian residential solar market – so this technology choice is one you won’t have to make.

Perhaps in the future…

There is actually a fourth solar panel technology type available being developed in Australia and elsewhere that uses dye sensitised solar cells. This technology is even lower in efficiency than thin film, but promises to be so cheap to make  you’d just put it everywhere to make up for that. The technology works by mimicking the photosynthesis process in plants. However, it seems dye sensitised solar cells are some way off from making a commercial impact.

>>Next: How to compare panel brands >>

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