Last updated: March 2026
Evergreen Solar was a Massachusetts-based solar manufacturer that pioneered string ribbon silicon technology — a revolutionary method of producing solar wafers with zero silicon waste. After a promising rise and significant public investment, the company filed for bankruptcy in 2011. Millions of Evergreen Solar panels remain installed and operating worldwide today.
Evergreen Solar Company History
- 1994 — Evergreen Solar founded in Marlboro, Massachusetts, USA. The company is built around the string ribbon silicon manufacturing process developed by Eman Sachs at MIT
- 2000 — Evergreen Solar lists on NASDAQ (ESLR), raising capital to scale manufacturing
- 2001–2007 — Expands manufacturing at the Marlboro, MA facility; string ribbon technology proves commercially viable and Evergreen becomes a significant US solar manufacturer
- 2007 — Signs a supply deal with BP Solar and other customers; receives $15 million in Massachusetts state subsidies and bonds to expand the Marlboro plant
- 2008 — Announces a joint venture with Jiawei Solarchina to build a 200MW string ribbon factory in Wuhan, China, seeking to slash production costs
- 2009–2010 — Closes the Marlboro, MA manufacturing plant (eliminating 800 jobs) and transfers production to the China JV. This decision generates major controversy given the state subsidies received.
- 2011 — Files for Chapter 11 bankruptcy in August 2011. Cannot service $484 million in debt despite Chinese production. Assets are liquidated.
Why Evergreen Solar Failed
Evergreen Solar’s failure is a case study in the brutal economics of the 2008–2012 solar shakeout:
- Silicon price collapse: Polysilicon prices fell from $400/kg in 2008 to $25/kg by 2011. Evergreen’s zero-kerf advantage was worth less as silicon feedstock became cheap.
- Chinese scale advantages: Even after moving to China, Evergreen couldn’t match the scale economies of fully integrated Chinese manufacturers like Suntech, Yingli, and Trina.
- Debt burden: The company had accumulated ~$484 million in debt financing its manufacturing scale-up. At sub-$1/W panel prices, no path to profitability existed.
- Technology gap: String ribbon cells were 1–2% less efficient than mainstream polycrystalline, limiting the premium pricing the technology could command.
Evergreen Solar Panel Model Specifications
Evergreen Solar produced several panel families. The ES-A series (using their proprietary string ribbon cells) was their primary residential and commercial product line:
| Model | Watts | Voc | Vmp | Isc | Imp | Efficiency | Cells |
|---|---|---|---|---|---|---|---|
| ES-A-195-fa3b | 195W | 22.5V | 18.0V | 11.62A | 10.83A | 12.3% | 85 |
| ES-A-200-fa3 | 200W | 22.7V | 18.2V | 11.75A | 10.99A | 12.6% | 85 |
| ES-A-205-fa3 | 205W | 22.8V | 18.3V | 11.97A | 11.20A | 12.9% | 85 |
| ES-A-210-fa3 | 210W | 23.0V | 18.5V | 12.15A | 11.35A | 13.2% | 85 |
Key note on Evergreen panel electrical characteristics: Evergreen ES-A panels use 85 string ribbon cells in an unusual configuration that produces a lower Voc (~22–23V) but much higher current (Isc ~11–12A) than standard 60-cell panels (~37V, ~8–9A). This matters when considering inverter compatibility or adding panels to an existing string — the electrical characteristics are not compatible with standard 60-cell poly or mono panels in the same string.
Historical Evergreen Solar Prices
| Model | Watts | Min Qty | Price/Panel (2009–11) | $/W |
|---|---|---|---|---|
| ES-A-195-fa3b | 195W | 2 | $444.60 | $2.28 |
| ES-A-200-fa3 | 200W | 2 | $452.00 | $2.26 |
Evergreen Solar Panels After 15+ Years
Evergreen panels installed between 2005 and 2011 are now 15–21 years old. Real-world reports from owners indicate these panels generally perform well — degradation rates consistent with standard polycrystalline silicon (~0.5%/year). The string ribbon manufacturing process produced mechanically robust wafers (no saw kerf stress fractures), and many systems remain operational with output near warranted levels.
Frequently Asked Questions
What happened to Evergreen Solar?
Evergreen Solar filed for Chapter 11 bankruptcy in August 2011 after accumulating ~$484 million in debt. The company was unable to compete with Chinese solar manufacturers despite moving its own production to China in 2010. After closing its Massachusetts plant (eliminating 800 jobs), the cost reductions weren’t enough to restore profitability. The bankruptcy liquidated the company’s assets; no successor company exists for warranty purposes.
What is the Evergreen Solar ES-A-195 specification?
The Evergreen Solar ES-A-195-fa3b is a 195W string ribbon silicon panel using 85 cells: Voc 22.5V, Vmp 18.0V, Isc 11.62A, Imp 10.83A, efficiency 12.3%. Note the unusually high current (~11A Isc) compared to standard 60-cell panels. Dimensions approximately 1559 × 812mm. MC4 connectors on most production runs. This was Evergreen’s most widely sold model in North America.
Where can I find Evergreen Solar panels?
Used Evergreen Solar ES-A series panels appear on eBay and solar salvage markets. Due to their unusual electrical characteristics (high current, low voltage), they are primarily useful for expanding existing Evergreen systems rather than mixing with other brands. Expect to pay $15–40 per panel for used examples in working condition.
