Panel buying tips 2017-11-22T16:32:23+00:00

Solar panel buying tips

Spend more money on inverters as solar panels are very reliable.

Manufacturer experience

The time a company has been in business is important, since it brings cumulative knowledge and experience. However, companies such as Seraphim were set up only eight years ago by leading individuals in the solar industry. Sometimes new companies have access to the very latest manufacturing plant, increasing the quality control and the latest techniques of panel production.

Origin of panels

Solar panels do not fail very often.  In independent performance test, many of the top panels are now manufactured in Asia.  Some Chinese companies, such as JA Solar, have more experience in manufacturing than some German companies such as Axitec and Solar-Fabrik.  80% of the panels in Europe are now manufactured in China.  The main two companies now left assembling solar panels in the UK are Romag and GB-Sol.

From 3.5 million panels manufactured and sold in Europe, only 137 panels have failed (0.00381%).


Manufacturer Experience (years)
Panasonic 41
LG 31
Hanwha Q.Cells 18
Canadian Solar 16
JA Solar 11
Manufacturer Company Origin
BenQ Taiwan Mexico/China
Canadian Solar Canada China
LG South Korea South Korea
Panasonic Japan Singapore
Jinko China China

Panel efficiency

Efficiency is about the size of the panel vs its output in lab conditions.


System 1:  16 x Seraphim 250w panels = 4kW system.

System 2: 12 x Panasonic 330w panels = 4kW system.

Both systems should produce the same amount of energy.

The main difference is the Panasonic system will take up less roof space, since it is a more efficient panel.

Panel efficiency is only important if you have a smaller roof space, which is not large enough for your desired system size.

There are only three reasons to buy high efficiency panels:

  • Small roof space

  • Improve layout of the panels due to space limitations

  • If you have two roofs, and one is facing closer to south, it can make sense to use high efficiency panels on the south facing roof.

Panel performance

Performance is about how the panels will actually perform on your roof.


System 1:  16 x Seraphim 250w panels = 4kW system.

System 2:  12 x Panasonic 330w panels = 4kW system.

According to lab tests, both systems should produce the same amount of energy.

However, in real life conditions the performance tends to vary quite a bit – up to 18%.

The only way to know which panels will perform better is by looking at independent field tests where panels are installed alongside each other in real life situations.

We also have empirical data on which panels appear to perform better than others.

Contact us to find out which panels perform best

Panel aesthetics

Frame colour

If you have a dark roof such as slate, we recommend black frames for aesthetic reasons.

Cell colour

There are two main types of cells:

  • Blue (polycrystalline)

  • Black (monocrystalline)

Backsheet colour

If you have a dark roof such as slate, we recommend black rather than white backsheets.  Black backsheets do increase the temperature of panels and slightly reduce the efficiency of the panel.

In the past, monocrystalline were more efficient than and considered superior to polycrystalline panels. This has now changed with some polycrystalline panels being more efficient than monocrystalline. In fact many of the top performing panels, in UK conditions, are polycrystalline. Some panel companies may have better performing polycrystalline panels, while others may have better performing monocrystalline panels.


Product warranty

When comparing panels, the product warranty is important, since if the reason for failure meets the warranty conditions, it will be replaced.  A 10 year warranty from a well-known financially stable manufacturer is probably worth more than a 12 year warranty from an unknown manufacturer.

In the 9 years we have been installing We have only had one panel where we have needed to make a warranty claim.

Performance warranty

Every panel sold in the UK needs to have a 25 year performance warranty – this means the panel will lose less than 20% of its output over 25 years.

It is extremely unlikely that anyone will ever claim under performance warranty, since the costs involved in proving the panel has failed will be more than the panel replacement cost.

For this reason, performance warranty is less important when comparing panels.


Panel performance does deteriorate over time (known as degradation or panel induced degradation – PID).  Some panels are appearing that are “PID free” such as some panels from LG and BenQ.