Despite the sharp U-turn in federal energy policy, solar cell innovators in the US just keep on persisting in the search for higher efficiency and lower costs. That includes the startup Solx, which has just teamed up with the California firm Caelux to manufacture new tandem perovskite technology at scale, in Puerto Rico. Puerto Rico Meets California In New Tandem Perovskite Solar Cell Venture For those of you new to the topic, perovskite solar cells have been the focus of much research activity since 2009, when a research team in Japan first demonstrated that synthetic forms of the naturally occurring mineral perovskite can convert solar energy to electricity. The lab-grown crystals have the advantage of relatively low cost, and researchers have also improved their solar conversion efficiency over the years. As a more economical alternative to traditional silicon solar cells, perovskites also lend themselves to high-volume, high-throughput manufacturing systems based on familiar roll-to-roll technology. There being no such thing as a free lunch, perovskite suffers durability issues as a standalone solar material. One emerging workaround is to pair it with silicon in a tandem solar cell. Among other alternatives, perovskite solutions can be applied in a thin film to glass, which can replace the conventional top glass coating typically used in silicon solar modules. While perovskites can reduce the solar conversion efficiency of the silicon layer to some degree, the overall result is a gain (see lots more perovskite background here). “Caelux’s proprietary technologies improve the performance of any new crystalline silicon module, making solar energy more powerful and cost-effective,” the company explained back in August of 2023, when it announced an additional Series A round spearheaded by the Singapore-based global investment firm Temasek, with participation from Khosla Ventures, Mitsui Fudosan, and Fine Structure Ventures among others. On its part, Solx has already laid the groundwork to absorb Caelux One into its business model. In November of 2024 the company announced plans to manufacture solar panels in Puerto Rico. In an email to CleanTechnica earlier today, Solx confirms that its new Caelux-enabled Aurora™ solar modules will be manufactured in Puerto Rico. In a press statement announcing their new partnership earlier today, the two companies also affirmed a new five-year, 3-gigawatt strategic partnership under which Solx will produce its Aurora solar modules with Caelux’s “energy amplifying glass” to achieve a healthy conversion efficiency of 28%. Production has already begun and the first batch has been earmarked for a US developer to be named later, with an eye on ramping up to high volume by next year. Wait, Why Puerto Rico? If you’re wondering why a US solar manufacturer should set up shop in Puerto Rico, well, why not? After all, Puerto Rico is a territory of the US. As such, manufacturers on the island can avoid crippling tariffs and take advantage of new Made-in-the-USA regulations. For that matter, the Jones-Shafroth Act of 2017 established US citizenship for residents of Puerto Rico, a status later clarified as applying to anyone born in Puerto Rico, regardless of where they live after birth. The efforts of current Energy Secretary Chris Wright to the contrary, Puerto Rico has already opened the solar energy bag and the cat has gone out. “Due to constant natural disasters that affect our Island and due to the electrical system’s weak infrastructure, it is important to find alternatives to prevent prolonged periods without electricity and counteract the effects of the constant electrical disruptions,” the Government of Puerto Rico continues to insist. “Power generators represent a temporary solution to the power grid’s unstableness. However, this equipment depends on imported fossil fuels, the supply of which has suffered disruptions in the past. The Energy lifeline’s fragility makes households vulnerable to health and safety risks,” they emphasize. Making Made-in-America Great Again The demand for solar energy in Puerto Rico or anywhere else in the US is not going anywhere anytime soon, despite the best efforts of US President Donald Trump and his Energy Secretary. The sun will keep shining long after both men leave office, and domestic stakeholders will keep on filling the need. Solx is Exhibit A. While the manufacturer launched its plan for Puerto Rico during the renewables-friendly administration of former President Joe Biden, Solx has not let the gloomy frown of the Trump administration slow it down. “We are committed to reshoring critical manufacturing capability while bolstering domestic energy security,” Solx proclaims on its website. “This is a defining moment for American energy manufacturing – U.S.-made hybrid tandem is no longer a theoretical, it’s now in commercialized production…This is how the U.S. leads again – by building the energy future at scale,” Solx co-founder and CEO James Holmes said in a press statement earlier today. “This partnership establishes a fully U.S.-based solar supply chain for Solx’s advanced manufacturing platform to support its Aurora™ module wherein the Caelux glass technology comprises the first power generation layer and Suniva’s U.S. produced solar cells make up the second power layer,” the partners emphasized. Echoing the theme, in the same announcement Caelux CEO Scott Graybeal emphasized that the partnership “revolutionizes the American energy industry to meet growing energy demand.” The third contributor to the Aurora solar module is the US silicon solar cell manufacturer Suniva, which is of particular interest from a Made-in-the-USA perspective. The company previously filed for bankruptcy in the early months of the first Trump administration while protesting illegal trade practices in the global solar industry. When the dust settled, Suniva emerged with a 1-gigawatt factory in motion in Georgia. A second, 4.4-gigawatt factory is currently in the works in South Carolina. “A strong domestic supply chain is essential to America’s energy future,” Suniva CEO Matt Card said in a press statement, reinforcing the theme expressed by Holmes and Graybeal. “This partnership demonstrates what’s possible when U.S. manufacturers and technology leaders align,” Card added. “By supplying domestically produced solar cells into Solx’s Aurora™ platform while also incorporating Caelux’s Active Glass, we are strengthening domestic energy security, creating high-quality American jobs, and enabling the next generation of solar innovation.” Between Suniva, Solx, and Caelux, that’s quite a lot of fire and brimstone to put on record, with the apparent aim of underscoring the weaknesses inherent in President Trump’s fossil-friendly “American Energy Dominance” policy. For that matter, Trump has yet to account for the exclusion of wind and solar energy from federal support. After all, the “American Energy Dominance” banner explicitly supports other forms of renewable energy, including biomass, geothermal, and hydropower, and even the yet-to-be realized area of marine energy. So, what exactly is wrong with wind and solar? If you have any thoughts about that, drop a note in the discussion thread. Image: The US startup Solx will manufacture new tandem perovskite solar modules in Puerto Rico, with solar cells from Suniva and perovskite glass from Caelux (tandem solar cell schematic courtesy of Caelux).