If you’re in the solar space, you’ve probably heard TOPCON—Tunnel Oxide Passivated Contact—mentioned more times than you can count lately. As someone who’s spent the last seven years at a TOPCON solar product supplier, I’ve seen firsthand how this tech has evolved from a niche upgrade to a mainstream workhorse that’s pushing solar efficiency past long-held limits. But the question I get asked most often by installers, project developers, and even fellow engineers isn’t about efficiency or cost; it’s about energy consumption specifically: “How much energy do TOPCON products actually use? And does that ‘cost’ eat into the benefits they promise?” TOPCON
It’s a fair question. For decades, solar has been sold as a “net energy positive” technology—the idea that over its lifetime, the energy it generates is far more than the energy that went into making it. But as we move to higher-efficiency tech, every watt counts. If TOPCON panels need more energy to manufacture, do they still deliver on that net positive promise? The short answer: Yes—by a wide margin. The long answer? It’s nuanced, and it varies depending on which part of the TOPCON lifecycle we’re talking about: manufacturing, operation, and end-of-life.
Let’s start with the part most people fixate on: manufacturing. To make a TOPCON panel, you’re not working with the old, standard PERC (Passivated Emitter and Rear Cell) panels we’ve relied on for the last 15 years. TOPCON’s design relies on a thin tunnel oxide layer (just 1–2 nanometers thick, thinner than a strand of DNA) and a heavily doped polycrystalline silicon layer on the back of the cell. That extra layer isn’t just for show—it’s what cuts down on electron recombination, letting the cell turn more sunlight into electricity. But does that extra layer add energy use to the manufacturing line?
For a long time, that was a valid concern. Early TOPCON production lines required extra process steps: high-temperature annealing to activate the doped poly layer, and precise deposition of that thin oxide. Some small-scale pilot lines back in 2019 and 2020 used up to 8% more energy per cell than PERC lines, according to data I helped compile for the International Technology Roadmap for Photovoltaics (ITRPV). But that was then. Today’s mass-produced TOPCON lines have optimized those steps so much that the energy gap is almost gone. At our facility, we run fully automated TOPCON lines that use just 2–3% more manufacturing energy than a comparable PERC line. Why? Two big reasons: better furnace design and streamlined process control. Modern annealing furnaces use 30% less power than the ones we had three years ago, thanks to improved thermal insulation and precision temperature zoning that cuts down on wasted heat. Plus, we’ve integrated real-time process monitoring that adjusts gas flows and temperatures on the fly, eliminating the energy waste from over-processing cells that didn’t need extra work.
It’s important to put that manufacturing energy number in context, though. Most of the energy used in making solar panels comes from two places: raw material processing (like purifying silicon into polysilicon) and cell manufacturing. For a typical 600W TOPCON panel, the total “embodied energy”—the energy used to mine, process, and fabricate the panel—is around 1,200 to 1,400 kWh. A comparable PERC panel is about 1,100 to 1,300 kWh. That difference is tiny when you look at how much energy the panel will produce over its lifetime. Let’s do the math: a 600W TOPCON panel in a good, sunny location (like the southwestern U.S. or southern Europe) will produce roughly 1,200 kWh per year, maybe more if it’s tilted perfectly and has minimal shading. That means the panel pays back its entire embodied energy in just one year—one year. Compare that to a PERC panel, which pays back in 10–11 months. The energy difference between the two? That’s just 18 to 22 days of extra electricity production. It’s negligible.
Now, let’s talk about the energy the panel consumes once it’s installed. Wait—do TOPCON panels use energy after they’re on your roof or ground mount? For the most part, no. Solar panels are passive devices—they don’t draw power to operate, unlike inverters or batteries. But there’s one small, often overlooked area: the performance of the panel itself, which ties into its “effective energy yield” over time. TOPCON panels have a big advantage here: lower degradation. Most PERC panels degrade at a rate of 0.5% per year in their first 10 years, then around 0.4% per year after that. TOPCON panels, thanks to that passivated rear contact, degrade at a rate of just 0.25% per year over their entire 25-year warranty period. That’s half the degradation. Let’s do another quick comparison: a 600W PERC panel that produces 1,200 kWh in year one will produce about 1,140 kWh in year two, 1,083 kWh in year three, and so on. After 25 years, it’s producing around 70% of its original output. A TOPCON panel? It produces 1,197 kWh in year two, 1,194 kWh in year three, and after 25 years, it’s still producing around 94% of its original output. That adds up to a huge difference in total energy over the panel’s lifetime. A typical 1MW solar farm with TOPCON panels will produce about 20% more energy over 25 years than the same farm with PERC panels. That’s 2,500 MWh extra over 25 years—way more than the tiny extra energy used to make the TOPCON panels.
There’s another angle here, and it’s one that my team has spent a lot of time researching: the energy used in the balance of system (BOS) for TOPCON installations. Wait—how does a panel design affect the balance of system? TOPCON panels have a higher open-circuit voltage, which means you can string fewer panels together for the same voltage output. That cuts down on the amount of copper wiring you need, and reduces the size of the inverter. Copper, of course, is an energy-intensive material to mine and process. If a farm uses 10% less copper for wiring and smaller inverters, that’s less embodied energy in the entire system, too. We’ve seen projects that switched from PERC to TOPCON cut BOS embodied energy by up to 5%, just from that wiring and inverter savings. It’s a secondary benefit, but it adds to the net energy gain.
Now, I know some of you are thinking: “What about bifacial TOPCON panels?” Most TOPCON panels sold today are bifacial—they can absorb sunlight from both the front and the back, bouncing off the ground or rooftop. Bifacial TOPCON has a slightly different manufacturing process than monofacial, right? The rear side is treated to allow light to pass through, which means we use a thin anti-reflective coating on the back instead of a full metal layer. Does that add energy use? Again, the answer is no. The deposition process for that back coating is actually more efficient than the metal plating process we use for monofacial PERC. And the extra energy from the rear side gain? That’s about 5–10% extra energy per year, depending on the ground albedo. If you install a bifacial TOPCON panel on a white gravel ground, you might get 15% more energy than a monofacial PERC panel in the same spot. That’s another win for net energy.
Of course, no technology is perfect. There are edge cases where TOPCON’s energy use can be a concern. For example, if you’re installing panels in a very low-light location, like the north of Europe, the difference in energy production between TOPCON and PERC is smaller—maybe 10% instead of 20%. So the extra manufacturing energy of TOPCON might take a few extra weeks to pay back, but it’s still negligible over the 25-year lifetime. Another edge case: if a manufacturer is still using old, inefficient TOPCON lines, not the optimized ones we run now. That’s why it’s important to work with a supplier that’s invested in next-generation manufacturing, not just scaling a 5-year-old pilot line. We upgrade our lines every 18 months, so we’re always reducing energy use while increasing efficiency.
I’ve had installers tell me: “PERC is cheaper upfront, so why should I care about energy consumption over 25 years?” That’s a fair point in a world where short-term costs dominate. But let’s look at the numbers. A 1MW PERC farm might cost $200,000 upfront, and produce $250,000 worth of energy over 25 years (at $0.10 per kWh). A 1MW TOPCON farm might cost $210,000 upfront, but produce $300,000 worth of energy over the same period. That’s a $40,000 difference in total revenue, even after accounting for the tiny extra manufacturing energy. The energy use question isn’t just about environmental impact—it’s about financial impact, too.
At the end of the day, the biggest misconception about TOPCON energy consumption is that it’s a trade-off between higher manufacturing energy and higher performance. But that’s not a trade-off—it’s a net gain. The extra energy used to make a TOPCON panel is less than 1% of the energy it will produce over its lifetime. That’s an incredible ratio, especially when you compare it to older technologies.
If you’re looking to switch to TOPCON products for your next project, I’d encourage you to ask your supplier specific questions about their manufacturing energy use, their degradation rates, and their performance data. At our facility, we publish all that data openly—no fine print, no misleading numbers. We’re a TOPCON supplier that’s focused on delivering products that are not just efficient, but truly net energy positive.
If you’d like to chat more about how TOPCON energy consumption works for your specific project, feel free to reach out to our team to talk through sizing, performance, and anything else you need. We’re here to help you make the most efficient, cost-effective choice for your solar needs.
SLAM References
International Technology Roadmap for Photovoltaics (ITRPV) 2023 Report
Journal of Photovoltaics, “Lifecycle Energy Analysis of Bifacial TOPCON and PERC Solar Panels” 2022
SEIA Solar Industry Version 2.0: Lifecycle Inventory Data 2021
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