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Second-hand solar panels: are they worth it?
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Second-hand solar panels: are they worth it?

10 mins 11 Jun 2021
Sometimes when buying an expensive product, it is worth considering second-hand options. Getting a used car makes sense, purchasing used home appliances does. But what about used solar panels? In this article we'll talk about second-hand PV modules and if it is a good idea to buy them at all.

Used solar panels are sold at a 60-80% discount

People put up their solar panels for sale for different reasons. Some have broken their panels and want to get at least something out of them. Others want to replace them with more modern and efficient models. Finally, some people just don't want to have panels anymore and decided to sell them.

There are lots of cheap used solar panels for sale on the internet. The discount on them is around 60%-80% of the original price. Pay attention: it doesn't mean that these are 60-80% cheaper than new models. The price mostly depends on the age of a panel and the damage it suffered.

Old panels are often damaged

When looking for second-hand panels, you have to accept beforehand that they are likely to be damaged. Some defects are easy to identify, others can be revealed only with the help of an expert or special equipment. For example, a broken junction box is self-evident, but microcracks can't always be found with the naked eye.

The damage to a PV module isn't always critical, but can be troublesome nonetheless: the output of a solar panel drops and, in some cases, the lifetime of a module decreases. Some problems you can fix yourself if you are up for it – for example, replacing a broken bypass diode is rather simple. However, sometimes it is not just worth it. Moreover, if you've bought damaged panels from someone, getting warranty support for them is usually a pipe dream. So, while purchasing old PV modules might save you money, it's a risky move overall.
Tilda Publishing
‘The presence of risk is undeniable when dealing with used goods. I would recommend buying systems no older than 10 years to be on the safer side. Also, some marketplaces list systems that are currently installed and are in good working order. It is the safest option, because any damages are easier to notice in a fully assembled system and you still get 15 to 20 years of warranty left.’
Nilda Jara
Solar PV sales manager

Panels now are cheaper and more powerful

Looking at the big picture, the rapid growth of the solar industry is another reason against used panels. Solar panels lost around 82% of their price over the last decade, according to the International Renewable Energy Agency (IRENA). Modern panels are simply cheaper than the old ones were, which suddenly makes the discount on used modules less appealing.

Modern panels are much more efficient than they were back then. They've become more tolerant to high temperatures,cloudy weather and shading. What's more, the performance of used panels will be much below their rated power output. On average, a panel loses 0.5% – 0.8% of its power output per year, so a panel manufactured in 2010 is going to perform at around 90-95% at best. Thus, a PV system out of old panels is going to take up much more space than a brand new one of the same capacity.

The bottom line is that new panel technologies and rapidly falling prices for PV modules make it unreasonable to go for second-hand options.

One or two used panels might work, but choose them carefully

While building a whole residential installation out of used panels is ill-advised, just a couple of used panels can come in handy. For example, buying a few used panels can be great for a small DIY project in your garage. So here are a few tips on choosing an old solar panel:

  • Look for a model without any visual signs of damage.

  • Check the power output of a panel with a voltmeter and compare it to its initial rated output to see the difference.

  • Burned out bypass diodes are common among old solar panels and can be replaced. You can get a panel with dead diodes for a really low price, purchase new ones and make yourself a nice module.

  • Check the connections of solar panels as they often pose a problem. In some cases, broken connections can be repaired with solder or conductive epoxy.

  • Don't be too afraid of the brownish hues of old solar panels – it often doesn't say anything about their performance. If the appearance of panels isn't a dealbreaker for you, you can get decent panels for a very low price.
Alongside panels, you might stumble across other used solar equipment. Keep in mind that it isn't as long lasting as PV modules. Here are approximate lifetimes of solar system elements:

  • Solar panel – 25+ year
  • Charge controller – 10-15 years on average
  • Deep-cycle battery – 2-10 years, highly depends on the type of battery and maintenance.
  • Inverter – 10-15 years, while being the most fragile part of the system.
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Illustrations – Marina Fionova