How To Pick The Right Solar Panels
What you need to know to pick the right solar panels for your home or Business
Choosing not just a good solar panel but the right solar panel can be extremely difficult. With so many options available on the market and so many conflicting pieces of information and advice it’s not an easy decision to make if you’re not sure.
That’s where we can help….
At Teho we get asked everyday, how do you choose a good solar panel?
In the Australian solar market there are lots of options. Some are cheap, some are outrageously expensive and some sit in the middle. These different price points generally raise more questions than answers. Does the difference in price reflect quality? Are these panels suitable for my roof? Will these panels last the test of time on an Australian roof?
At Teho, we narrow it down to 4 key factors when choosing a solar panel.
- The Warranty
- Temperature coefficient
- The Panel Efficiency
- The Manufacturer
A few calls to a few solar retailers and you’ll quickly learn that most of their “sales pitch” on their panels is about the warranty. While the warranty is important we can tell you it’s easy to be told how good the WRONG warranty is.
When it comes to solar panels there are 2 warranties, the manufacturers product warranty and the manufacturers performance warranty.
The difference between the two is huge.
The product warranty will cover any faults and issues with the solar panel for a period of time. For entry level to mid range solar panels expect that warranty to be 10-15 years, while more expensive and premium solar panels will cover a product warranty of 20-30 years.
The warranty is slightly different depending on the manufacturer, some will cover parts and labour and others will only cover parts and you’ll need to foot the bill when it comes to the labour.
The manufacturer’s product warranty is the most important warranty.
The performance warranty to us is absolutely useless, it’s tough to monitor and nearly impossible to claim.
The performance warranty is nearly always judged over 25 years, sometimes 30 and will warrant an amount of degradation across that period. For example a panel manufacturer who we won’t name, will warrant at least 98% output during the first year, thereafter 0.54% degradation per year. At least 93.1%of nominal power up to 10 years. At Least 85% of nominal power up to 25 years (this is a good solar panel by the way).
Solar sales people are notorious for stating that the solar panels they use have a 25 year warranty but don’t mention which one. Most of the time it’s the performance warranty and not the product warranty which really matters.
Like we said, this performance warranty is absolutely useless but can be an indicator of quality if the solar panel manufacturer is going to make some bold output claims.
A commonly overlooked piece of information is the temperature coefficient of a solar panel. A solar panel is sized by watts and the perfect solar panel temperature is around 25 degrees.
Solar panels use light to convert to energy but like most pieces of technology they hate heat. Solar panels will produce less when they are hot and each manufacturer’s temperature coefficient will state how much.
It might be a hot 35 degree day but you can appreciate the solar panels on your roof may well be up to 50 degrees!
You can expect the output to each degree over 25 degrees by about half of a percent (0.5%).
Given how hot it can get in Australia, and how often it gets hot a good temperature coefficient is vital.
The Panel Efficiency
Each solar panel has a panel efficiency. What’s important to understand is that it’s measured on the output in wattage versus the size of the solar panels. It doesn’t mean that miraculously one 370w solar panel will capture more sunlight than someone else’s 370w solar panel.
This is because panel efficiency isn’t based purely on output. It is based on output vs the size of a panel. So to put it simply, if you are comparing two panels of identical outputs in watts, the more efficient panel will just be smaller than the less efficient panel however both will still produce the same amount of power.
It’s only really important to you when you are looking at maximising your roof space. If your roof is smaller and you want a larger system, it’s a good idea to get a solar panel with a bigger output. If you are spoilt for space, don’t worry too much about it.
Things that are much more important than panel efficiency are things like manufacturing quality which has a much more direct relationship with real world performance and reliability.
Research on the manufacturer is a good idea. Understand who is sitting behind the warranty to determine if they will be around long enough to service it, if they have an Australian based office for warranty claims and a few YouTube videos on their manufacturing and quality processes wouldn’t go astray either.
You can tell we love a good YouTube video.
Now we have covered the 4 key factors to look for when choosing a good solar panel or the right solar panel, there are some other things to cover off.
Tier 1 Solar Panel ranking
Don’t use this as your decision to purchase a solar panel, otherwise you’ll have about 100 different solar panels in contention to be installed on your roof. The tier 1 solar panel ranking system is used by banks to determine the bankability of a solar panel manufacturer for large solar farms. You aren’t installing solar by the megawatt on your roof
Polycrystalline VS Monocrystalline
There is a misconception one is better than the other, it’s simply not true. There are manufacturers out there who only manufacture monocrystalline solar panels but there are others who think polycrystalline solar panels still have a long way to go while still being low cost and good quality. We can tell you it really doesn’t matter and there is no reason why you should be worried about having either one on your roof. For more information read our whole guide on Polycrystalline VS Monocrystalline.
More Wattage Per Panel = More Generated
Not true, a 24 x 275 watt solar panel will produce the same amount compared to 18 x 370w panels. There may be marginal differences at scale but not enough to be stuck on this as a decision.
Higher wattage panels are more popular because in Australia we tend to use lots of electricity and our roof space will only be able to handle a certain amount of panels.
If you are looking at 370 watt panels and you’re told by someone their 390 watt panel is better, you now know, it’s rubbish.