Buying Solar Panels – What You Need To Know

3. Don’t Buy Cheap Solar Panels Online

Do not buy cheap panels from webshops for your roof. Especially if they also sell budget household items.

If you see spectacularly cheap solar panels for sale online, pause for thought before snapping them up, hoping you can find a sparky to wire them up for you. Here are the risks of buying cheap solar panels online:

• Those bargain panels are likely so cheap because they are not eligible for the solar rebate, meaning your solar system just got $2,000 – $4,000 more expensive.
• Most good installers won’t touch cheap online solar panels.
• Another risk is that they may arrive damaged. If solar panels are not meticulously protected and shipped, they are susceptible to microcracks, which can significantly impact their performance and lifespan.
• The 25+ year warranty is with the online company you bought from – not the installer.

I advise buying the solar panels from the company that will also do the installation so they take responsibility for everything, including claiming your solar rebate and all warranties.

4. Specifications That Matter: Efficiency, Degradation, PMax

Solar panels have dozens of specifications. You can compare them on my solar panel comparison table. But as a consumer, I’d argue there are only three you need to know about:

Efficiency (%)

Efficiency measures the percentage of sunlight energy hitting a panel’s surface that is converted into electrical energy.  The higher, the better.  Today’s solar panels typically achieve efficiencies from 21% to 23%.

Why is high efficiency good? Well, the higher it is, the more watts of electricity you’ll get per square metre of panel, allowing a system to generate more energy from the same amount of roof space.  

So, if roof space is at a premium or you just want super-duper PV technology, look into higher-efficiency panels. The good news is that, in 2024, good budget solar panels will be as efficient as premium ones. A budget option like Jinko achieves an efficiency of 22.53%, which is comparable to premium brands like Winaico (23%), SunPower (22.20%) and REC (21.20%).

Degradation (% per year)

All solar panels become less efficient over time, but the rate of degradation varies. A budget panel may degrade at 0.5% per year, while premium panels like REC or SunPower degrade at about 0.25% per year. Over 20 years, this translates to:

• Budget panel: 10% efficiency loss (e.g., 22% drops to 19.8%).
• Premium panel: 5% efficiency loss (e.g., 22% drops to 20.9%).

While “double the degradation” sounds bad, in real terms, the difference in energy yield is only around 5% over 20 years.

If you value longevity and top performance, premium brands like REC and SunPower with lower degradation rates might be worth the investment. But if you’re budget-conscious, high-quality panels from brands like Trina and Jinko still provide excellent value, with minimal loss in energy output.

PMax Temperature Coefficient  (%/ºC)

Solar panels love light but hate heat because high temperatures reduce their efficiency. 

Temperature Coefficient of Pmax — or just Pmax — tells you by how much.  This will be around -0.35%/ºC for a typical panel.  The smaller this is, the better.  For every degree over 25ºC a panel’s output will be reduced by this percentage.

REC and Aiko panels provide the best Pmax at -0.26%/ºC.  If you live in a hot climate and want maximum energy on hot days, Pmax is worth considering.

5. Solar Panel Warranties

Insist on at least a 25-year manufacturer’s warranty (also called product warranty) on the solar panels, which covers defects in workmanship and materials.

Pay particular attention to the fine print of warranty docs.  Ideally, you’ll want a warranty that will replace defective panels and cover labour costs.  But the majority of warranties don’t promise this.  Avoid any that say the panels have to be sent away to make a claim.  Also, consider the history and experience of both the panel manufacturer and the company installing them.  Are they likely to still be around in 10 or 20 years if something goes wrong?

Finally, ensure the warranty isn’t tied to an expensive service contract. You don’t want to feel compelled to shell out $500 a year for a bloke to hose down your solar panels just to keep your warranty. By the way, this sort of warranty stipulation is likely unenforceable under Australian Consumer Law!

While Australian consumer law is strong and can require companies to provide support they don’t include in their warranties, it’s always good to have a warranty that promises comprehensive support, as you are less likely to have to fight to get it.

6. Country Of Origin: Are Chinese Panels Crap?

Some people insist the best solar panels are made in Germany, and all Chinese solar panels are crap. Follow that previous link for a deeper discussion on this, but I find that talk borderline xenophobic.

You may have Pauline Hanson style reasons for not buying Chinese products. However, as far as quality is concerned, many Chinese brands are world-class. Some are crap, but if you think “Chinese” is synonymous with “low quality”, what do you think about your iPhone, Macbook Pro, or Tesla Model 3?  Yep, made in China …and they’re all high-quality, sophisticated devices.

7. How Green Are Solar Panels?

Solar panels provide a huge environmental benefit over burning fossil fuels by generating energy from sunlight.  But do some provide more benefit than others?  The answer is yes.  But, provided they are reliable, the difference is very small compared to the drawback of not having solar.

If your goal is the lowest greenhouse gas emissions possible from your solar, I recommend looking at the following:

1. Do the panels have a reputation for reliability and a long manufacturer’s warranty?  The largest waste of solar resources occurs when cheap and shoddy panels have to be replaced after only years of use rather than multiple decades.
2. Are the panels high-efficiency?  These require less material per watt of panel capacity and so, all else equal, result in lower emissions from manufacturing and transport.
3. The manufacturer’s own claims about emission reductions.  Some companies are more committed to cuts than others.   

Solar panels can also be recycled.  While still in its early days in Australia, panels can be recycled in Europe with a 95% material recovery rate.  If you want easier and safer-to-recycle panels, you can pay extra for lead-free ones.  REC is the only company currently producing these, but other manufacturers may follow.