Who makes the world’s most efficient residential solar panels? The panels listed here have earned the right to be considered when homeowners are looking for a system to provide the best savings over the years. Remember that solar technology is moving quickly and striving for higher efficiency with each new panel created, so manufacturers regularly discontinue solar panels and release new,
more efficient panels to take their place. This chart will help get you started
understanding available solar panel efficiencies from a variety
of manufacturers:

Rank Manufacturer Country Model # Type Efficiency Power Warranty
1 SunPower USA X21-345 Mono 21.5% 240 WP 25 YEARS
2 JA Solar China JAC M6PA-4 Mono 20.9% 290 WP 10 YEARS
3 Sanyo Japan HIT Double 195 Mono 20.5% 195 WP 20 YEARS
4 SunPower USA 327-320 Mono 20.4% 327 WP 25 YEARS
5 SunPower USA 245-235 Mono 20.1% 245 WP 25 YEARS
6 Schosser Systems Photovoltaik China SSP180-260 Mono 20% 260 WP 2 YEARS
7 SunPower USA E19-320 Mono 19.8% 320 WP 25 YEARS
8 AUO Taiwan Sun Forte PM318B00 Mono 19.5% 318 WP 5 YEARS
9 Sanyo Japan VBHN245SJ25 Mono 19.4% 245 WP 20 YEARS
10 SunEdison USA R355BzC Mono 18.2% 355 WP 10 YEARS
11 SunTech Japan STP285S-20/Wem Mono 17.5% 285 WP 10 YEARS
12 Yingli Green Energy China YL225C-24b Mono 17.1% 225 WP 10 YEARS
13 Phono Solar China PS330M-24/T Mono 17% 330 WP 10 YEARS
14 JA Solar China JAP6 60- 275/4BB/RE Poly 16.8% 275 WP 10 YEARS
15 Canadian Solar China 275 M Mono 16.8% 275 WP 10 YEARS
16 REC Norway REC275TP Poly 16.7% 275 WP 10 YEARS
17 JA Solar China JAM6 (R) 72-325 Mono 16.7% 325 WP 10 YEARS
18 Jinko Solar China JKMS320P Poly 16.5% 320 WP 10 YEARS
19 JA Solar China JAM6 48-215/SI Mono 16.4% 215 WP 10 YEARS
20 Trina Solar China 315 Poly 16.2% 315 WP 10 YEARS
21 JA Solar China JAM6(TG)-60-265/SI Multi 16.2% 260 WP 10 YEARS
22 Yingli Green Energy China YL205P-23b Poly 15.8% 205 WP 10 YEARS
23 Kyocera Japan KU255-6BCA Poly 15.5% 255 WP 10 YEARS
24 Sharp Japan ND-F4Q300 Poly 15.3% 300 WP 10 YEARS
25 Yingli Green Energy China YL 235 P-29b Poly 14.4% 235 WP 10 YEARS

Understanding Solar Panel Efficiency

Solar panel efficiency can make an enormous difference in the savings realized on monthly utility bills over the long run. The efficiency of solar panels is based on the ability to convert sunlight into electricity. If the same amount of sunlight shines for the same duration on two different panels, the one with the highest efficiency will produce the most electricity.

Though solar panel efficiency is rising quickly, some companies still do claim efficiency numbers that are garnered only under strictly controlled test conditions – which is not what homeowners get when they install a system. In the real world, efficiency depends upon the type and brand of solar panel being used, as well as on-site considerations. Getting the maximum efficiency from your solar panel depends on several factors:

  • Irradiance (the amount of sunlight)
  • Wind speed and temperature
  • Angle of the panel
  • Panel direction
  • Shading

What can homeowners reasonably expect?

“On the high side at around 22.1 percent and on the low about 14 percent,” MacLeod said. “I almost never see a panel produce to its full efficiency rating in field conditions. There are usually as much as 20 percent in losses.”

To ensure solar panels are top-notch in terms of efficiency, it’s time to do some homework. This guide is designed to help homeowners understand how efficiency works, how to choose the best solar panels for the job and learn how to compare solar panels to find the ones that work best for a particular environment.

Solar Panel vs. Solar Cell Efficiency

Solar panels are only as efficient as the solar cells inside them – but why doesn’t the higher solar cell efficiency translate into higher solar panel efficiency? One of the top reasons is simply how those cells are used in the panel space.

“Look at the cell layout on the panel face,” MacLeod said. “Some manufacturers make more efficient use of the available area on the front and back of the panel. More cells, less cells, types of cells – all determine efficiency.”

Crystalline silicon PV cells have laboratory energy conversion efficiencies as high as 25 percent for single-crystal cells and 20.4 percent for multicrystalline cells. However, industrially produced solar modules currently achieve efficiencies ranging from 18–24 percent.

U.S. Department of Energy

Manufacturers are getting smarter about configuring solar panels, just as the industry is getting better about producing higher-efficiency cells for those panels.

“Eight years ago we were using panels that were 12 percent efficient, now we are up to 22 percent. Pretty good so far,” MacLeod said. “All the manufacturers are competing against each other for the efficiency prize.”

Manufacturers to watch are SunPower, LG, Solar City, Panasonic along with many others.

Kevin MacLeod
Kevin MacLeod, owner of KPS Solar in New York and Florida

Another issue with higher-efficiency solar panels is the prohibitive cost.

“There are cells out there that are as high as 44.5 percent efficient but will take a lot of time before they come to market,” MacLeod said. “Pathfinder on Mars used cells that were 44 percent efficient but cost over a million dollars.”

Obviously there is huge room for growth with solar efficiency, but the world of solar changes very quickly, and companies are already tackling the efficiency issues. MacLeod said he believes that the near future will show big changes in wattage, battery storage technology and the makeup of the panels themselves.

“Efficiency will continue to increase as Multi Layered Cells and Gallium Arsenide cells enter the market,” he said. “Panel wattage is on the increase as well. Ten years ago it was 185 watt panels, now its 300s, 315s, 345s, 360s and on.”

Look for dramatic efficiency increases in the next
five to 10 years.

Kevin MacLeod
Kevin MacLeod, owner of KPS Solar

What Affects Solar Panel Efficiency?

Though the technology that makes up the panel itself has a strong impact on efficiency, the site where the solar panels are installed also has a hand in the amount of power created. In some areas of the country, solar panels will be more efficient simply because of a more conducive environment. But efficiency can vary dramatically from one neighborhood to the next or even from one home to another on the same street, based on site considerations. The following are the biggest factors in solar efficiency outside of the panel itself.


Obviously, the amount of sunlight hitting a solar panel will
determine how much of that potential energy is absorbed.
But shade does more damage than you might think:
the efficiency of the entire solar array can be compromised
by a little bit of shade on one solar panel, as it has the potential to
‘shut down’ or slow the efficiency of all connected panels. The best
possible site is a roof with no shade at all.


While it might seem that the hotter the area, the better the efficiency, that’s not true. Solar panels don’t necessarily like heat, which is why they are installed to allow a few inches of room between the roof and the panel – it allows for airflow that helps cool them down. Though some solar panels are designed to handle hotter temperatures, most actually experience a decrease in efficiency when exposed to high temps.


A roof with a true south slope is optimal for efficiency; however, others can work well. Though a direct east or west orientation will produce about 20 percent less power than a true south facing, even that can be improved with the right tilt of the panels.

Roof tilt

The angle at which the sunlight hits the panel can drive efficiency up or down. When the sun hits the panels at a shallow angle, the light reflects away, which means the panels cannot collect as much as they would if facing the sun directly. Some roofs have a pitch that means the sun never quite hits the panels directly; this might be remedied by installing the panels in such a way that compensates for the tilt of the roof. This requires a strong site survey and excellent design to achieve maximum panel efficiency.

Solar Panel Tracking Systems

With so many issues concerning the tilt and orientation of solar panels, some homeowners might be curious about tracking systems. These systems do just what it sounds like: they track the path of the sun by moving the solar panels to achieve the best solar coverage possible.

Single-axis trackers

follow the sun from morning to evening; dual-axis trackers also track from morning to evening, but take into account seasonal changes as well. Dual axis trackers obviously have more opportunity to capture energy; they can provide up to 40 percent more harvesting power than fixed arrays.

Passive trackers

rely on the heat of the sun to warm liquid in canisters on the side of the array; the liquid in the exposed canister turns into a gas, which pushes excess liquid into the shaded canister, thus tilting the array throughout the day. Active trackers rely on photosensors or software to determine the route of the sun and uses hardware to move the array accordingly.

It sounds like a good idea: it would allow homeowners to capture as much of the sun’s rays as possible. But MacLeod has some misgivings.

“Trackers are mostly used for ground mounted systems,” he said. “They are ideal for areas like New Mexico and Nevada where the irradiance factors are the highest. They also have motors and moving parts that can fail in extreme environmental conditions of the northeast. As the cost comes down on trackers, then I might give more positive consideration to using them.”

As solar panels become more affordable, the costs of trackers will continue to drop in order to compete the in the market. But besides the cost, there are a few other downsides to consider.

  • Weight limitations

    Solar trackers might be very heavy, depending upon the size of the array, which doesn’t make them a viable option for many roof-mounted systems.

  • Extra maintenance

    They are made of moving parts, which can lead to more maintenance requirements and opportunities for the system breaking down.

  • Shorter warranty

    The warranty might be troublesome as well: companies routinely offer anywhere from two to 10 years under warranty, while inverter and panel warranties typically start at 10 years and go up to 25 years or more.