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Types Of Solar Panels Available

Choosing Your Solar Panels - What Are Your Choices?

When shopping around for a solar power installation for your home (or business) one of the things that will set different installers apart is the type and brand of solar panel that they offer you.

So how do you assess what kind of panel is best for you?

Here are some of the factors you should weigh up:

1. Solar Panel Efficiency

When I talk about solar panel efficiency I am talking about the ratio (as a percentage) of energy in the sunlight hitting the panel area - to - electrical energy in the wires coming out of the panel.

Why is a high efficiency good? Well the higher the efficiency, the more Watts of electricity you will get per square meter of solar panel.

So the higher the efficiency the smaller that solar panel becomes for the same electrical output.

Does that mean that you should just choose the panel type that has the highest rated efficiency percentage? It's not that simple I'm afraid. Because some panel types cost more to manufacture than others, they can still turn out more expensive that other types with a lower efficiency. So if you are going on price alone you would look at the dollars per Watt figure instead.

However, the advantage of higher efficiency panels is that generally the higher the efficiency, the smaller the panel you will need. So if roof space is at a premium, or you just want super-duper technology look into higher efficiency panels.

2. Cost

The obvious calculation here is: How many watts of electricity are you getting per dollar of panel?

As a general rule like most things in life you do tend to get what you pay for so be cautious about choosing solely on price. However, there are often bargains to be had, special deals and some suppliers are just more competitive. Just make sure that you are comparing apples to apples in terms of warranty, service, product quality and so on.

3. Quality and Warranty

It is not easy to determine the quality of solar PV panels, inverters and installation service from a quote. However, the warranty statements and conformance to quality standards gives a pretty good indication.

Pay particular attention to the fine print around things like where you might have to send your products if there is a problem, whether they are fully accredited and approved for use in Australia and the experience of the company supplying you. Will they be around in 10 or 20 years if something goes wrong?

4. Specification

Like most products solar PV panels can have different specifications. Things to watch out for are:

the power tolerance on solar PV panels (i.e. are you getting 150W or 150W +/-10%? Some are much better than others.
The voltage rating and co-efficient of temperature. Solar PV Panels should be rated to 100V DC minimum for safety. A good co-efficient of temperature can indicate a solar PV panel that performs slightly better in higher temperatures.
Who is the manufacturer? Some companies buy in solar PV panels and self brand them. Who is the real manufacturer and how will they support you?

5. Looks.

Some people prefer the look of some panels to others. As a General rule Thin Film panels look more uniform and some people prefer this, although they take up much more space. Some suppliers can integrate the panels into your roof, at a price of course.

As a general rule a more "utilitarian" look will be cheaper and super slick integrated systems are more expensive.

6. Embodied Energy.

If this is primarily an environmental decision, you may find it important how long it will take you to generate the same amount of electricity that it took to make the panel and mounting equipment in the first place. The installer should be able to give you this 'energy payback' figure for each panel type.

Here's a rundown of the four main types of solar PV panels that are available:

1. Single Crystalline (also called mono crystalline)

Some think of these as the 'Rolls Royce' of solar panels. They are one of the oldest technologies, and more expensive to make, but they have the highest efficiency.

These can typically get 12-17% efficiency in the real world.

They are made from wine-bottle sized single crystals of ultra-pure silicon and sliced up like salami to make the individual wafers which are then converted to solar cells. Each circular wafer has its sides cut square and the solar panel is made up of a matrix of solar cells laid flat like tiles on your bathroom floor.

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, they perform about the same (in efficiency and power terms) as poly crystalline.

Some manufacturers use special techniques to make ultra high performance monocrystalline solar PV modules, such as back surface fields, laser grooving and hybrid technologies.

Here's what they look like.

2. Poly Crystalline (also called multi crystalline)

These solar PV panels are also made from silicon, but the silicon used is slightly less pure and they are cast into blocks rather than sawn from a single crystal. This is why the crystals are visible - they are randomly arranged.

Once cast, they are sawn into square blocks and then into wafers and cells like mono crystalline, but a little easier to make. They are very similar to single-crystalline in performance and degradation, except the cells are typically slightly less efficient, typically 11-14%. However, because there is no wasted space between the corners of the cells, when they are encapsulated in solar PV panels, the performance is almost identical to mono crystalline solar PV panels.

3. String Ribbon

This is a relatively new technique that uses less energy to manufacture than the 2 above. They drag a pair of metal strings through a thin film of molten silicon and it creates a ribbon of silicon that doesn't need to be sliced or diced any further.

Efficiency is 12-13%, and degradation performance is as the poly and mono-crystalline panels. The lower efficiency means a panel that is approx 30% bigger though.

4. Thin Film or Amorphous

There are a variety of ways of making thin film modules using all manner of elements including silicon vapour, cadmium telluride, gallium indium arsenide or various hybrids of these elements.

Although these processes have been around for a while, the modern variations of the thin film manufacturing process are pretty new technology, so I would argue that 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. Although its improving, they are typically 8-10% efficient so they are around twice the size for the same power, and much heavier, so you need a big and strong roof!

So to sum up:

There is nothing really to distinguish between multi and mono-crystalline except their looks!
Thin-film are can be cheaper, but will be at least twice the area, and no-one is 100% sure how much they will degrade in the long term (so get a performance guarantee!).

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