Worldwide PV Panel Efficiency and Energy Density Comparison

Updated with More Panels and More Recent Data as of December 8, 2010

One of the popular questions we’re always hearing is “which panels are best?” Another version of that same question: “Are PV solar panels becoming a commodity?” or “Is there that much difference between one brand or another?” There are certainly many different factors to be considered when selecting PV solar panels. Some installations have limited areas where energy density is a major consideration. Some consumers want to know what REAL cost per watt will be, so they are interested in PTC (see NOTE below explaining PTC) DC power ratings compared to STC DC power ratings. Obviously, price, warranty and customer support must all be factored into the buying decision.

We decided to assemble a couple of comparison charts below, listing only “tier one” quality panels. We have used the  California Energy Commission (CEC) list as of December 2010 for the PTC numbers, as well as currently available manufacturers’ product data sheets for panel square footage to create a quick comparison of STC to PTC efficiency (see bold faced column) for similar monocrystalline and polycrystalline photovoltaic solar panels with similar STC DC rating (or as near as we could find) We used a 240W panels as the baseline. If a manufacturer didn’t offer a 240W panel, we looked for the closest panel to that size. The resulting PV efficiency chart shows  Sanyo, Shuco and Canadian ranked at the top (only exceeded by thin film), followed by a group of manufacturers that some might find surprising. Suntech, China Sunergy, Phono Solar, CEEG, Kyocera, Mitsubishi and Solarfun are all positioned with SunPower in the top ten in efficiency of PTC . Here is the table of popular brands, sorted with the best STC to PTC efficiency at the top and the worst at the bottom.

It’s interesting to take a second look at this same list, this time sorted in order of the PV panel energy density (highest PTC  watts per square foot -  or as we like to call it, “AC watts per square foot”). When we look at solar panels this way, SunPower stands out at the top and thin film falls to the bottom. This is no surprise, as it’s common knowledge that SunPower panels require less roof space than other panels, while thin film requires much more space. Sanyo is second on the list (also, no surprise). Samsung, a new entry into the PV space, and Kyocera occupy the third and fourth positions. The next three panels might raise a few eyebrows: China Sunergy, CEEG and Phono Solar. The top ten is rounded out by Suniva, JA Solar and Solarfun. WholeSolar is proud to offer six of these top ten high performance PV panels at very compelling pricing. You can follow the link to product pages elsewhere on the WholeSolar website and then leave us your name, email and zip code on the right panel of this (or any WholeSolar website) page. Here’s the same table as above, except that it is sorted in order of the highest PV panel energy density:

Of course, there are many ways to make panel comparisons. Just today Greentech Media featured an article written by Shyam Mehta titled Efficiency Leaders in Crystalline Silicon PV. It presents a different approach to amking such comparisons and argues that the gap is closing rapidly among the top panel makers.

NOTE:

PTC refers to PVUSA Test Conditions, which were developed to test and compare PV systems as part of the PVUSA (Photovoltaics for Utility Scale Applications) project. PTC are 1,000 Watts per square meter solar irradiance, 20 degrees C air temperature, and wind speed of 1 meter per second at 10 meters above ground level. PV manufacturers use Standard Test Conditions, or STC, to rate their PV products. STC are 1,000 Watts per square meter solar irradiance, 25 degrees C cell temperature, air mass equal to 1.5, and ASTM G173-03 standard spectrum. The PTC rating, which is lower than the STC rating, is generally recognized as a more realistic measure of PV output because the test conditions better reflect “real-world” solar and climatic conditions, compared to the STC rating. All ratings in the list are DC (direct current) watts.

Neither PTC nor STC account for all “real-world” losses. Actual solar systems will produce lower outputs due to soiling, shading, module mismatch, wire losses, inverter and transformer losses, shortfalls in actual nameplate ratings, panel degradation over time, and high-temperature losses for arrays mounted close to or integrated within a roofline. These loss factors can vary by season, geographic location, mounting technique, azimuth, and array tilt. Examples of estimated losses from varying factors can be found at: http://www.nrel.gov/rredc/pvwatts/.