Solar Panels

Solar panels are everywhere but from the ground they all look the same and it is very hard to tell the good from the bad. All panels however are not created equal. There are major differences, which affect the performance, lifespan, economics and safety of a solar power system.

Low quality solar panels are a risk both to the financial returns you may get from your investment in solar power, but can also be a significant fire hazard so you need to select your solar modules carefully.

As a starting point, before purchasing a solar power system, consumers should ensure that the components being offered meet Australian standards and are approved for sale in Australia.To be eligible for government subsidies the solar modules must meet Australian standards.The Clean Energy council has a frequently updated list of all approved solar modules and inverters

http://www.solaraccreditation.com.au/approvedproducts/modules.html

For information on the solar panels Meridian Solar install, and the companies that manufacture these panels, refer to our Solar Products page          

Cells

Solar modules or panels, consist of many individual solar cells that are electrically connected together.  The majority of solar cells are made from silicon wafers that have metal circuitry printed on their surface. In a phenomenon known as the photoelectric effect, when the photons in sunlight hit a silicon molecule it causes the release of an electron from the atomic structure. These electrons are collected by the tiny metal circuits printed on the solar cell, and continue to flow on through the other cells in the solar panel. This flow of electrons is electricity.

There are 3 main types of silicon cells used in solar modules.

Mono-crystalline cells are created from one large crystal or ingot of silicon. This silicon ingot is sliced wafer thin and one wafer makes up a cell. Mono-crystalline panels are easy to identify by the cropped corners of the cells, and the white diamond spaces in between the cells. Mono-crystalline cells are the most efficient at converting sunlight to electricity so are readily used in residential installations where often, roof space is                                                                                                       at a premium.

 

 

Poly-crystalline or Multi-crystalline cells are formed from many silicon crystals that are grown together and then sliced into wafers. These cells are recognizable by the many crystal structures and angles within a cell. Poly-crystalline modules are slightly less efficient than mono cells however because the cells are square and there are no gaps between cells, the output of equally sized mono and poly panels is about the                                                                                                                        same.

 

 

Amorphous silicon is not so much a cell but a thin film of silicon sprayed onto a backing surface. These panels are cheaper than crystalline models however the efficiency of the panels is much lower due to less silicon being used. This means more panels are required to achieve the same output as a solar system using crystalline panels. For this reason amorphous solar panels are rarely used in residential installations due to limited                                                                                                                roof space. There is also evidence to suggest                                                                                                                amorphous panels degrade at a faster rate                                                                                                                    than silicon panels meaning there lifespan is                                                                                                                shorter.

 

Note: There are other solar panels on the market that use materials other than silicon to create electricity however these are not widely used in residential solar applications

Degradation

All panels degrade or become less efficient over time. That is, the silicon in the solar cell becomes less efficient at converting the energy from the sun, into electricity. A normal rate of degradation is about 0.5% of output, per year.

The degradation rate is much higher in low quality panels, resulting in significantly less energy being produced over the lifetime of the panel and therefore reducing the returns on your investment.

Normally manufacturers offer warranties that guarantee the panel will be working at say 90% capacity after 10 years and 80 percent after 20 years, however many of the lesser known start-up companies that offer low cost panels, may not be around to honour their warranties in the long term.See our warranty section for a discussion on these issues.

Faults known as Hotspots can develop in solar cells due to the degradation of silicon. Hot spots can cause the solar cell to short circuit, damaging the solar panel and creating a potential fire hazard.

 Poor quality silicon, as found in some cheaper solar panels, will significantly increase the chance of hotspots occurring.

Frames

The frame of the solar module encapsulates the solar cells and protects the fragile edges of the solar glass. Anodized aluminum is the most common material used for its strength and durability. Each side of the frame must be bonded together to ensure conductivity and earthing capability. The frame must be firmly attached to the backing sheet and the glass to prevent moisture penetration. This is usually done with a combination of machined grooves, and silicon adhesive.

Low cost panels from unknown companies may have problems with moisture penetration, causing the yellowing of the solar cells and delamination of the solar glass.

Junction Box

The junction box is where the electricity generated by the solar panels is transported to the cables and moved on in the electrical circuit.

Low quality junction boxes are subject to water penetration and can lead to fire risk if the connections inside are poorly soldered. Connections can become loose and cause short circuits

Diodes

Solar panels include by-pass diodes to protect a cell when there are shading issues. When a cell is shaded, the bypass diodes divert the electricity around the shaded cells and it continues through other cells in the module that are not shaded. This maximizes the output of the solar panel as it still operates, all be it at a reduced level, despite having some cells in shade. If there were no diodes, the electricity flowing from other cells in the panel would try and push through the shaded cells. The cell would heat up and could be damaged. Once the shading issue has been removed, the diodes allow the panel to resume normal operation.

Connection plugs

The solar panels are joined together with connecting plugs. There are many types of plugs on the market and many imitations of leading brands.

Be very cautious of cheap solar modules that will probably have low quality connection plugs. Not only will these plugs reduce the efficiency of the solar power system, as the electricity will not flow as freely through the cabling, but they can also be a safety issue as there is a build up of heat in some connectors resulting in an increased fire risk.

Glass

The glass on the front of the solar panel is very important as it can have a big impact on how much light is directed onto the solar cells and thus how much energy is produced by the solar panel. The glass is pre-stressed and also provides protection for the cells from the elements. Quality panels have glass that is 3-4 mm thick and have a hydrophobic coating on the surface. This coating allows water to freely run off the surface of the panels and means the panels are regularly cleaned when it rains.

Low quality solar panels use glass that is much thinner than industry leaders and without a hydrophobic coating. This means the panels are much weaker and they are much more prone to the build up of dirt and debris which will decrease their output.