- Panel Wattage
It seems obvious and essential, but it is surprising how many people do not know the quoted wattage of their panels. It is best to stick with the latest panels available for the most outstanding efficiency and performance. Be cautious of companies trying to sell old 330 or 350W panels or less as they are much cheaper, but they’re also old technology and take up more room on your roof.
Even if you have plenty of roof space, make sure that you use it wisely. The predictions are that electric vehicles will start to replace more and more petrol and diesel cars, so when this happens, you may want to install a larger solar system to power the car. Your roof might not seem all that important now, but in 5 or 10 years it might be unbelievably valuable to you, so getting a modern technology panel will be important.
- Cell Type
Most panels nowadays are made of mono-crystalline cells such as Mono-Perc, Mono N-Type and Mono P-Type.
- Mono N-Type is the best in terms of performance and quality but also the most expensive.
- Mono-Perc is designed to be a cheaper way of achieving similar results to the Mono N-Type cells.
- Mono P-Type is standard P-Type Mono-Crystalline cells.
It’s rare for anyone to be selling Poly-Crystalline panels nowadays. If you have been quoted Poly-Crystalline panels, I’d suggest looking for another supplier. Poly was a good technology a few years ago, but the advancements have overtaken it with Mono-Crystalline cell production. It is now very rarely seen in the Australian market, and only used in the cheap as chips categories.
- Temperature Coefficient
The Temperature Coefficient is a reference to how your panel will operate in very hot weather. You will see a range of figures for temperature coefficient on many datasheets.
Generally, the most important and relevant is the Temp Coefficient of PMAX; this is an indication of how much a panel will degrade from heat. This is particularly important for customers as the Sunshine Coast climate and heat will affect the performance of the panels over time.
Solar panels are usually tested at a cell temp of 25°C, but here in South East Queensland, it gets a lot hotter than that. On a typical 25°C day the panels will get to a cell temperature of about 50°C, a lot hotter than the tested temperature.
For example, if the temp coefficient is -0.4% per °C, and the ambient temperature is 25°C, the panel performance will reduce by 10% on a typical day. The calculation goes like this:
0.4% x (50°C -25°C) = 0.4% x 25°C = 10%
Therefore, if the temp coefficient is -0.5%/°C, you would be losing an additional 2.5% through heat just from a single panel. Efficient solar panels like the LG panels (link to LG panel page) nowadays have temperature coefficients in the mid-’30s, which can make a massive difference in total yield over the lifetime of the system, especially here on the Sunshine Coast. Did you know for example the LG NeON R solar panels have a temperature coefficient at PMAX of only -0.30 %/°C one of the pests in the industry?
- Product Warranty
The product warranty is the most crucial warranty of all. Most product warranties state that if the product fails from a fault of the product itself, such issues will be covered by the manufacturer.
For example, if water entered from a broken seal caused by a manufacturing fault, then the panel will fall under the product warranty. The good quality suppliers will replace the panel and pay for labour.
The bad quality suppliers, if still around, will hand you a small amount of money to put towards the cost. And the ugly ones will just ignore you or be no longer in business. We hope that you never need to use a product warranty, but if you do, you want to have a well-known manufacturer with a large Australian Head Office to cover the damage expense. For many, the cheap solar deal could suddenly get a lot more expensive, especially when you consider that STC’s are being phased out.
- Performance Warranty
We call the performance warranty a bulldust warranty as for most (not all) it is not worth the paper it’s written on. That might sound a bit scary, but as a long term solar supply and installation company we’re sick of hearing cheap manufacturing companies claiming that their panels have 25-year warranties.
Many of them know full well that they will only last a couple of years and that their business will be out of the picture as soon as issues start to arise. Performance warranties are incredibly tricky to prove, and usually, the cost of proving that the panel is faulty costs more than the panel is worth. The cheap pane manufacturers know it’s a costly exercise, so they push back till the customer is exhausted. It’s an unfortunate aspect of cheap solar.
As a specific example at the moment, we know of an installer in Brisbane who has tested panels installed a few years ago and he alleges that these panels are having significant lower performance than expected. Unfortunately, the manufacturer is pushing back on the claim, and the end customer is the loser with a significantly underperforming system.
As previously mentioned, select a large diversified manufacturer with a strong presence in Australia. They are more likely to have cash in the bank to support warranties if it is required.
- Solar Panel Dimensions
All panels are different in size, and it’s vital to check that the solar panels you buy will fit on your roof. Often the lower-priced panels have impressive wattage numbers, but when you check their size, they are huge. So it is not because of the great technology that they have a high wattage, but because of their size.
It is also crucial they work on your roof in a manner that allows the structure of the roof to support the panels, to ensure they maintain their warranty.
All solar panels have an installation manual supplied from the manufacturer that stipulates how to install the panels correctly. There is also a set of Australian Standards that strictly specify multiple limitations. The most popular panels in Australia nowadays generally consist of 60 cells (or 120 cells if split cell technology) for residential roofs and 72 cells (or 144 cells if split cell technology) for commercial roofs.
We typically install 60 and 120 cell panels on residential properties and some small commercial rooftops, whereas the 72 cell or 144 split cell panels are generally used for commercial rooftops due to their size. Commercial panels are much larger and often unsuitable for a residential roof due to the structure and weight.
- Solar Panel Installation
On the Sunshine Coast region, the screw lines on a residential Colorbond rooftop are typically 900mm apart whereas a commercial roof is usually around 1200mm or more.
A commercial solar panel is usually over 2.1m long x 1.1m wide, so when used on screw lines of only 900mm, there can be an overhang at each end. As a result, installing commercial size panels on a residential rooftop will likely void the warranty of the panel, as one will not be able to comply with the manufacturer’s specified clamping zones.
On the other hand, residential size panels are approximately 1.7m x 1m. Which will fit much better in the given space, it will also protect the manufacturers’ product warranty on your panel.
Caution! Are commercial panels better than residential solar panels? No, they aren’t better, they’re just larger. The technology is usually exactly the same.
Watch out for companies selling commercial panels for a house as a premium ‘high wattage’ panel. The reason they are ‘high wattage’ is because they are larger in size. It’s like saying that a 2L bottle of milk is of better quality than a 1L bottle of milk.
The milk is the same quality, but the 2L is simply a larger bottle. Commercial panels can work on some houses, depending on the roof structure. This is best to discuss with your installer.
A premium solar panel if installed incorrectly, will have no warranty. SolarWide is the only Authorised LG Dealer on the Sunshine Coast and we have been installing solar for over 10 years, so trust us when we say that we know how to install solar.
LG also ensure that all their LG dealer network install products to the highest level and within manufacturers specifications. So go SolarWide – Go Quality Solar.
8) Country of Origin
The country of origin does not necessarily play a significant impact in the quality of the solar panel. What matters most is the production process, who the manufacturer is, and what quality control measures they have in place. Also, their local footprint and other business activities in Australia is something to consider, as if they have many other business inks, they are less likely to disappear.
You can find out this information on our product pages or directly on the manufacturers’ website. If you would like to arrange a free, no-obligation quote for solar or would like to learn more, please give us a call on (07) 5309 5871 or ask your questions via the chatbox.