Last updated: March 2026
Schott Solar — originally known as RWE Schott Solar — was one of Europe’s most technically innovative solar panel manufacturers, pioneering Edge-defined Film-fed Growth (EFG) silicon technology as an alternative to standard wafer cutting. A joint venture between German energy giant RWE and precision glass manufacturer Schott AG, the company had deep roots in European solar manufacturing before being wound down in 2012. This guide covers the full history, EFG technology, panel specifications, and what owners of Schott Solar systems should know today.
Schott Solar Company History
- 2003 — RWE Schott Solar formed as a joint venture between RWE Group (a major German energy utility) and Schott AG (a German specialty glass and materials company). Combines RWE’s solar manufacturing experience (inherited from ASE Americas) with Schott’s glass expertise.
- 2003–2008 — RWE Schott Solar operates as one of Europe’s five largest solar manufacturers, with facilities in Germany, Spain, and the Czech Republic. Also operates a US facility in Billerica, MA inherited from ASE Americas.
- 2009 — As part of a restructuring, RWE sells its stake in the solar joint venture. Schott AG takes full ownership and the company is renamed Schott Solar.
- 2010–2012 — Schott Solar struggles with Chinese competition driving down global panel prices. Despite being a technologically sophisticated manufacturer, cost-competitiveness proves impossible.
- 2012 — Schott Solar announces closure of all crystalline silicon manufacturing operations. The company winds down panel production entirely. The Schott AG parent company still exists (as a specialty glass manufacturer) but is no longer in solar panels.
EFG Technology: Schott Solar’s Technical Innovation
Schott Solar (through its ASE Americas predecessor) developed and commercialized Edge-defined Film-fed Growth (EFG) — a ribbon silicon manufacturing process that, like Evergreen Solar’s string ribbon, aimed to eliminate silicon kerf waste.
How EFG works:
- A shaped graphite die is partially submerged in molten silicon
- Silicon is drawn up through the die by capillary action, forming a thin film at the die’s edges
- As the shaped die is pulled upward, silicon solidifies in the die’s shape — Schott used an octagonal tube geometry
- The octagonal silicon tube is then laser-cut into individual wafers of the required shape
- The octagonal tube geometry allowed 8 wafers to be cut from each tube pull, improving manufacturing efficiency
Like Evergreen’s string ribbon, EFG produced polycrystalline silicon wafers with significantly lower kerf waste than standard ingot-and-saw processes. EFG panels had a characteristic appearance: slightly uneven grain texture with occasional visible artifacts from the die-edge growth process.
Schott Solar Panel Model Specifications
Schott Poly 230/235 Series (Standard Polycrystalline)
| Model | Watts | Voc | Vmp | Isc | Imp | Efficiency |
|---|---|---|---|---|---|---|
| SCHOTT Poly 230 | 230W | 37.2V | 30.0V | 8.34A | 7.67A | 14.1% |
| SCHOTT Poly 235 | 235W | 37.4V | 30.2V | 8.52A | 7.79A | 14.4% |
| SCHOTT Poly 240 | 240W | 37.6V | 30.4V | 8.68A | 7.90A | 14.7% |
Schott EFG Series (Ribbon Silicon)
| Model | Watts | Voc | Vmp | Isc | Imp | Technology |
|---|---|---|---|---|---|---|
| ASE-100-GT-FT | 100W | 23.1V | 18.6V | 5.93A | 5.38A | EFG Ribbon Si |
| ASE-165-GT-FT | 165W | 23.8V | 19.2V | 9.50A | 8.59A | EFG Ribbon Si |
| ASE-200-GT-FT | 200W | 24.0V | 19.4V | 11.40A | 10.31A | EFG Ribbon Si |
Note: ASE (Advanced Silicon Energy) was the predecessor brand used by RWE Schott Solar for EFG panels. Some older EFG panels carry the ASE brand rather than Schott. All specifications at STC.
What Happened to Schott Solar?
Schott Solar shut down all crystalline silicon panel manufacturing in 2012. The decision came after years of Chinese competition making European manufacturing economically unviable. Schott AG (the parent company — a specialty glass manufacturer) still exists and is active in other industries, but no longer produces solar panels. Schott AG does manufacture specialty glass used in solar concentrating systems (CSP), but this is a different business entirely from the crystalline silicon panels the solar subsidiary produced.
For Schott Solar panel owners: No warranty claims are possible against Schott Solar as the entity no longer exists. Schott AG disclaims responsibility for the solar subsidiary’s obligations. Work with your original installer for any warranty or service issues.
Frequently Asked Questions
What happened to RWE Schott Solar?
RWE sold its stake in the solar joint venture in 2009; the company became simply Schott Solar under full Schott AG ownership. Schott Solar then closed all crystalline silicon manufacturing in 2012, unable to compete with Chinese panel pricing. The Schott AG parent company still operates as a specialty glass and materials manufacturer, but the solar panel subsidiary is gone.
What is EFG solar technology?
Edge-defined Film-fed Growth (EFG) is a method of producing silicon solar cell wafers by drawing molten silicon through a shaped die, forming a continuous ribbon that solidifies into an octagonal tube, which is then cut into wafers. Unlike standard ingot-and-saw manufacturing, EFG produces wafers with minimal silicon waste (no kerf). Developed by ASE Americas (predecessor to RWE Schott Solar), EFG is no longer in commercial production.
Are Schott Solar panels good?
Yes — Schott Solar panels were high quality for their era. German manufacturing standards and Schott AG’s materials expertise (especially in glass quality) produced panels with excellent encapsulation and durability. EFG panels had slightly lower efficiency than cast polycrystalline but comparable real-world performance. Installed Schott/ASE panels from the 2000s–2012 era that are still operating are typically performing within expected degradation ranges.
