Not all solar panels are created equal. EnergySage uses a classification system for solar panels based on performance, quality, durability and warranty to help solar shoppers compare the quality of all of their options. A solar panel’s efficiency (how effective a panel is at converting sunlight into electricity) is a key factor determining solar panel quality, and manufacturers are constantly improving their processes to create higher-efficiency solar panels.
How manufacturers are improving solar panel efficiency
Solar panels are made up of many components, and there are similarly many opportunities to improve the solar panel manufacturing process.
Manufacturers can make solar panels more efficient in two basic ways:
- Improving the solar cells themselves
- Improving the way the cells are placed in the panel
There is an alphabet soup of acronyms and buzzwords being floated around about improvements in technology coming down the pipeline. These are just a few of the improvements that different manufacturers use to increase the efficiency of their solar panels.
Improved antireflective coatings, textures, and other materials
Have you ever looked at a solar panel and seen that one of the solar cells is slightly off color? The consistency of the color of a solar cells is one indication of its quality and its ability to produce power. Developing more consistent manufacturing processes can be a relatively easy way to improve panel efficiency.
Reduce the shading caused by the busbars
When you look at the front of the solar panel at the cells, there may be silvery lines across them going horizontally or vertically. These are tiny metal wires on the front of the solar cells, called “busbars,” and they help the electricity which is generated flow out of the cell into your home.
However, they do cause some of the light to be reflected, rather than be converted into energy. Manufacturers have been working to make the wires thinner, or even eliminate them altogether. The highest-efficiency premium plus panels have “rear contacts” where all the wires are on the back and the entire front of the cell is a single color.
Use both sides of the solar cell
Most solar panels use a standard white or black “backsheet” which provides a sturdy backing layer to attach the solar cells. But some panels are clear on both sides, and can absorb light from either side. This technology has sometimes been called “Bifacial” meaning both sides of the solar cell can absorb light.
Pack cells in more tightly on the panel
Those white spaces you see between cells and along the edge are wasted solar panel area. In addition the corners of the cells themselves are cut off, leaving even more space. Manufacturers are finding ways to eliminate the gaps or even overlap the cells and produce more power.
High-efficiency technologies here or coming down the road
Technology improvements will increase the efficiency of all types of solar panels, and the performance improvements will be seen through all of EnergySage’s classifications.
EnergySage Classification | Types, Cell Efficiency | New Technology Improvements |
| Premium Plus | Monocrystalline Silicon 20%-22% | Sunpower (IBC), Panasonic HIT, PANDA, Zebra, |
| Premium | Monocrystalline Silicon 18-20% | PERC, n-PERT (Passive Emitter Rear Contact) Bifacial |
| Standard | Monocrystalline or Polycrystalline 15-20% | Aluminum Back Side Contact (AL BSC) |
| Economy | Thin film solar 15% or below | CdTe, CIGS |
Thin film improvements: “organic” solar cells
Thin film solar cells are not to be dismissed, although they are less efficient on paper than silicon solar cells and other technologies. They have a distinct advantage, they do not require the expensive silicon substrate. They can be made flexible and used in other design applications, without the standard frame, glass, and backsheet which makes up the majority of today’s panels. Some of them being organic in nature may be better for the environment. They’re also recyclable and very easy to manufacture.
Silicon improvements (mono- or poly-crystalline)
Silicon solar cells will continue to improve, as the manufacturers develop new structures, or commercialize old ones. Major manufacturers are switching to PERC, HIT, or IBC to improve cell efficiency. Monocrystalline and polycrystalline solar cells are the bulk of the market today and will continue to improve.
Next-generation cells
Gallium-Arsenide, multi-junction, and other advanced technologies could be the next generation of solar cells. While they aren’t yet at the point of mass production, these do have better theoretical efficiencies in the lab, and could show promise.
Should you wait for higher solar panel efficiency?
Every few months, another solar manufacturer makes headlines by announcing that they’ve created the “world’s most efficient solar panel,” leading many homeowners to wonder, are high-efficiency solar panels worth the wait? On the EnergySage blog, we break down why now is the time to go solar, even though solar panel efficiency will continue to increase in the months and years ahead.
Justin Gee was a Senior Automation Engineer at SolarCity, and has extensive experience in high-tech manufacturing, automation, data analysis and process modeling.
