Great question and the short answer is no, there are many types of solar panels. Spend a little time on Wikipedia & Google and you can dig into the history of solar panels and their development over the years. There were earlier solar cells but it was in the 1950s that the first solar panels went into production. Silicon Valley, CA has been a hot-bed for solar panel development over the years and when patents are granted other companies have to get creative and find better solutions.
Before diving too deep it's important to first distinguish that we are only focused on solar panels for generating electricity (PV) as there are solar panels designed for thermal heating (to get hot water). As an FYI since 2010 where we live, here in Hawaii, any newly built single-family dwelling is required to have a solar water heater on the roof by law!
We are also not getting into Concentrator Photovoltaics (CPV) which uses lenses or curved mirrors to focus sunlight onto small, highly efficient, multi-junction (MJ) solar cells. Likewise for Concentrated Solar Power (CSP) systems that use mirrors to concentrate a large area of sunlight into a receiver where it's converted to heat and then electricity.
So with solar PV panels (for electricity) you will often read that there are three main types:
Mono-crystalline - dark blue/all black cells that you find in SunPower/Maxeon panels
Poly-crystalline - marbled light blue cells typically with 'silver lines' on the front
Thin film - lower efficiency but very thin & flexible (can often be rolled up)
Mono Poly Thin film
Both mono-crystalline and poly-crystalline solar cells are made from crystalline silicon, which makes up the vast majority of solar panels (90-95%) whilst thin film only accounts for around 5-10% of solar panels.
The SunPower and Maxeon solar panels we have available are all mono-crystalline and as such are built with the highest efficiency solar cells. This means more power in less space, important when "roof space" for solar is a premium aboard your yacht. The other main advantage of SunPower and Maxeon panels is that they use patented IBC technology (see below).
IBC technology means more power in less space, pretty important when "roof space" is a premium aboard your yacht.
Key word here is that the panels we sell are 'patent protected' and as such the competition comes up with new technologies that may get better results in the lab but have a hard time bringing it to production. As such mono-crystalline IBC panels continue to be the most robust & efficienct panels available to purchase.
So there are now many more names you will come across as solar technology & design develops and trends change. A few blogs I have read now say there are 4 main types and include PERC in the list but really there are many more variations. Without getting too deep into the detailed science of each here's our quick guide to some of the terminology you can find around solar today:
IBC - Interdigitated Back Contact
This is patented cell technology from Maxeon that is used in all SunPower and Maxeon solar panels we have available. All of the electrical connectivity is done on the back of the solar cell, hence there are no 'silver lines' on the front of the cell. This means none of the active solar surface is blocked so more sunlight is captured. It uses a solid copper backing to each cell which gives the cell strength, is more protected from corrosion being on the back and copper is a better conductor than the baked-on aluminum paste (silver lines) used by other panels. Another patented feature are the robust, stamped metal interconnect tabs that allow room for expansion and contraction (so less prone to corrosion & breakage)
IBC technology is fundamentally better
PERC - Passivated Emitter and Rear Contact
Invented in 1983, you might even see Mono-PERC and Poly-PERC depending on the type of silicon cell used but a special layer is added to the back surface of the solar cell (a "passivating" layer) which helps to reflect light back into the cell. This increases its efficiency at converting sunlight into electricity but is more prone to LID (Light Induced Degradation)
PSC - Perovskite
Since 2016 Perovskite solar cells have been the fastest-advancing solar technology. I will often see Perovskite mentioned a lot in my news feed, a click-bait article for example about "Perovskite reaching dizzying new heights of efficiency that will turn the solar industry on its head!" Simpler to produce but does have longevity issues and toxicity issues (due to them containing lead). You may also see new 'Perovskite-silicon tandem' solar cells being tested in the lab, it's hard to keep up!
Bi-facial
Traditional solar panels only capture light on the front side of the panel, whereas bifacial allows light to also be captured on the back side of the panel. You could then call traditional panels "mono-facial" but it's not a term you will see very often! There can be a yield gain of up to 30% with bifacial panels, eg a 100W bifacial panel could yield up to 30W from the backside for a total yield of 130W.
Sounds great BUT a huge factor is albedo - or the amount of light a surface reflects. Sure over snow (or a white RV roof) you will get better results, but water absorbs nearly all of the light so only a fraction bounces back up to the back side of the panel. Also on a boat the racking/mounts/arch will block the active solar surface of the back side.
Read our blog post for more details about "bifacial solar panels on a boat"
Bi-facial panels may or may not have a transparent back sheet
CIGS - Copper Indium Gallium Selenide
This is the main technology for 'thin-film' solar panels, aswell as Cadmium Telluride (CdTe), Amorphous Silicon (a-Si) & Copper Zinc Tin Sulfide (CZTS), which allows for much thinner and flexible panels (can be rolled up). Much lower efficiencies (~16%) so if you have a large roof space no problem, but on a boat where "roof space" for solar panels is a premium then it's an issue. Notable companies making CIGS panels include Miasole & Sunflare
EOS 120W CIGS - 109.85 sq.cm = 1.09 Watts per sq.cm
SunPower 100W - 64.77 sq.cm = 1.54 Watts per sq.cm or 41% more solar (and that's not factoring in the 'dead space' where the SunPower logo is so it's even more!)
TOP-Con - Tunnel Oxide Passivated Contact
TOP-Con solar cell technology is one of the latest trends in the solar industry, since 2013 it was developed as an upgraded and more advanced version of the PERC/PERT technology. The basic idea of the TOP-Con concept is that the metal of the connection contacts does not come into contact with the silicon layer. This prevents charge carrier recombination, which typically causes performance losses at the rear of the cell. Another advantage is that the structure is only slightly different from PERC/PERT solar cells, meaning that manufacturers can use the same production line with a few improvements to produce TOP-Con solar cells.
HJT - Heterojunction Technology
HJT is a hybrid technology, combining aspects of conventional crystalline solar cells with thin-film solar cells. Development began in the 1970's but really took off after the expiry of some patents around 2011. Heterojunction solar panels work similarly to conventional crystalline panels but the main difference is that it uses three layers of absorbing materials (combining thin-film and traditional crystalline technologies). It has a less expensive manufacturing process and panels are less affected by temperature (ie. continue to perform well as panel temperatures increase). Some big manufacturers of HJT include Jinergy and Meyer Burger
Get in touch if you have any questions about the different types of solar we have available.
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