Evergreen Solar Panels ES-E Series

The Evergreen 215 Watt ES-E Series solar module offers an affordable and truly eco-friendly solution for home owners seeking to install a solar power system to meet their electricity needs.

Evergreen Solar Panels for homesThis solar model utilizes Evergreen‘s proprietary String Ribbon solar wafers produced with the minimal possible impact on the environment.

Evergreen Solar state that the manufacture of their panels has the smallest carbon footprint in the industry and that their “… String Ribbon wafers are made with a fraction of the emissions that result from making conventional silicon panels.”

We consider Evergreen solar panels to be genuinely green products and would welcome any further feedback from our readers.

Let’s have a closer look at the Evergreen 215 Watt ES-E Series model.

Solar Cells’ Raw Material: Multi-crystalline silicon

Evergreen solar wafers are made of multi-crystalline silicon (aka polycrystalline silicon, or polysilicon).

EVERGREEN SOLAR PANELSWhile, conventionally polysilicon is made from large blocks of molten silicon which are cooled, solidified and cut into individual solar cells (with waste silicon cuttings produced as a by-product of this process), Evergreen‘s own String Ribbon technology uses a totally different approach.

Evergreen‘s silicon ribbons are produced when “…two high-temperature filaments are pulled vertically through a silicon melt, and the molten silicon spans and solidifies between the filaments.”

Once this is done, “… the wafer strips are cut into smaller pieces for further processing into solar cells.”

This method produces virtually no silicon waste and, in this sense, is much more gentle in its impact on the environment than the conventional method.

Not to mention the fact that Evergreen‘s method consumes a lot less energy during the manufacturing process as well.

Rated Power: 215 Watt

The rated power of this model is 215 Watt as measured at Factory Standard Test Conditions (STC).

STCs require that a solar panel receives 1000 watts per square meter of solar irradiance at a solar cell’s temperature of 25°C.

Evergreen Solar point out that all their panels are rated for the minimum guaranteed power that each of its panels will deliver.

For example, each 215-watt panel will deliver at least 215 watts of power “…upon initial delivery of the panel to the customer”.

But in fact, each Evergreen solar module’s maximum rated power measured at STC conditions may be more than its minimum power by as much as 2.5%.

So the maximum power (Pmax) for Evergreen 215 watt solar panels will actually be 219.99 Watt (Ptolerance of -0%/+2.3%).

Evergreen Solar refer to it as a “positive power tolerance” and are obviously very proud of this fact, since the rest of the competing brands provide mostly negative power tolerance ratings for their panels (that is, when the actual electricity generated by a panel may be less than its maximum rated power).

Ex., Sharp solar panels have a Pmax tolerance range of +10% / -5%.

PTC Power Rating: 191.9 Watt

While STC is widely used as a common standard for determining a solar panel’s output, the industry acknowledges that it does not reflect “real world” (but just factory) conditions, and thus is not an accurate measure for this purpose.

Instead, more realistic conditions have been set by an alternative PTC measure (PVUSA Test Conditions) developed in California, US.

PTCs require that a solar panel receives 1000 watts per square meter of solar irradiance at 20°C temperature of the air (and not that of a solar cell’s) at 10 meters above the ground, and wind speed of 1 meter per second at 10 meters above the ground.

The PTC rating of this Evergreen 215 watt solar panel (ES-E Series) is 191.9 Watt.

Solar Module’s Voltage:

  • 35.6 V – Open Circuit Voltage (Voc)
  • 29.0 V – Maximum Power Voltage (Vpm)

Open circuit voltage (Voc) is a maximum voltage produced by a solar panel when there is no current running through it. At this point, the solar panel doesn’t produce power as such (power (watt) = volt x current).

What we are more interested in is the maximum power voltage (Vpm).

Vpm is the maximum nominal rating for the voltage produced when the current runs through the panel as well (i.e., when the actual watt power is generated).

So, the maximum power voltage for this Evergreen 215 watt solar panel is 29.0 V.

Solar Module’s Current:

  • 8.12 Amp – Short Circuit Current (Isc)
  • 7.43 Amp – Maximum Power Current (Ipm)

Likewise, short circuit current (Isc) is a maximum current produced by a solar panel when there is no voltage running through it.

Maximum power current (Ipm) is produced when the voltage runs through the panel.

The maximum power current for this Evergreen 215 watt solar panel is 7.43 A.

If power (watt) = Volt x Current, then the maximum nominal power output of this panel will be:

29.0 V x 7.43 A = 215 Watt

Solar Module’s Efficiency: 13.1 %

Evergreen Solar Panels ES-E Series on a houseThis property indicates how efficient this Evergreen solar panel is at converting solar light it receives into usable solar power.

Please note that there is a difference between the efficiency rate of a solar cell and that of a solar module as such. A solar module’s efficiency will always be lower than that of an individual cell’s.

The higher the efficiency rate, the more power a solar cell / panel can generate per given area.

This indicator is usually used to compare the performance of different solar panel brands to each other but is not necessarily the most relevant one for making a purchasing decision.

We agree with Evergreen Solar‘s opinion regarding efficiency:

… efficiency … is a measure of power generated by every square foot of the panel’s surface … But higher efficiency doesn’t necessarily mean more electricity. It only means that less space is required to generate that electricity. And since high-efficiency panels usually come with high price tags, it is only in heavily space-constrained applications that efficiency is a driving consideration.

Nominal Operating Cell Temperature (NOCT): 45.4°C

NOCT is the temperature reached by open circuited cells in a solar panel under a set of conditions which are closer to “real world” than STC requirements.

The lower this temperature is, the better the panel will work (i.e., more efficient).

NOCT temperatures below 47°C are considered to be good.

Temperature Coefficient (Rated Power): -0.43% per 1°C

The rated-power temperature coefficient shows how much power your solar panel will lose when this panel’s temperature rises by 1°C above 25°C.

So, this Evergreen 215-watt solar panel will lose roughly 0.92 Watt per 1°C temperature rise above 25°C.

The lower the temperature coefficient is, obviously the better.

Other Issues

This Evergreen solar panel uses a special anti-reflective tempered glass which, according to Evergreen Solar, can generate at least 2–3% more electricity in a “typical” installation than panels using standard glass.

It contains 120 multi-crystalline solar cells.

Qualifications

This Evergreen module is listed with Underwriters Laboratories (UL), to the UL 1703 standard.

UL 1703 standard certifies that this product has been tested for safety and passed it.

This model also has other international quality-related certifications: IEC 61215, IEC 61730, IEC 61701 & ISO 9001 certificates.

Warranty

As of January 1, 2011, Evergreen Solar provides a materials and workmanship warranty for this solar module of 120 months from the date of sale.

The warranty for power output is:

  • 90% or greater than the module’s Minimum Specified Power Rating at STC for 10 years from the date of sale to the purchaser, and
  • 80% or greater than the module’s Minimum Specified Power Rating at STC for 25 years from the date of sale.

Recent Developments

Until recently, Evergreen Solar‘s panels were mostly produced in the US – the fact that the company was very proud of, with its main manufacturing facility in the state of Massachusetts.

However, latest reports (as of January 2011) suggest that due to the need to cut production costs to stay competitive it is now shifting its manufacturing base to China.

Let us hope that this will not affect the quality of its production.

Evergreen Solar Panels – User Feedback!

We always put a lot of effort into researching any solar panel brand/model that we cover on this site.

But we welcome any feedback from anyone who uses Evergreen solar panels in their homes or any other solar installations.

Please, please share your experiences with us and let us know what you think about Evergreen panels!

We also welcome any comments from solar professionals who either install these panels for their clients or have some other professional knowledge of them.

Evergreen Solar Panels – User Feedback!

We always put a lot of effort into researching any solar panel brand / model that we cover on this site.

But we absolutely welcome any feedback from anyone who uses Evergreen solar panels in their homes or any other solar installations.

Please, please share your experiences with us and let us know what you think about Evergreen panels!

We also welcome any comments from solar professionals who either install these panels for their clients or have some other professional knowledge of them.