Not long ago, energy harvesting in IoT was more curiosity than capability. A lemon-powered microcontroller as a demo could make a crowd smile, but rarely sparked confidence in product development. And yet, today, we find ourselves in a very different place. Where battery-less devices aren’t just possible, they’re increasingly in demand.

During this year's The Things Conference, a panel titled “Squeezing every drop of juice from your energy source” hosted and moderated by Mark Patrick from Mouser Electronics, brought together key voices from the energy harvesting ecosystem. But it was Edin Golubovic, VP of R&D at Enocean, who reminded the audience just how long and hard-won this journey has been, and why it’s worth it.

“Our first major task was proving that energy harvesting goes beyond lab demos.”

For Enocean, that early milestone came more than a decade ago in the form of a batteryless, kinetic-powered switch. A simple function, zero idle current, no external power. It was clean, clever, and practical. But the customers started demanding self-powered multi-sensors that operates reliably under real-world constrains.

To get there, Enocean had to start from scratch. No Bluetooth Low Energy. No LoRa. No energy-optimized PMICs. They developed their own radio protocol, chips, and firmware stacks. Focused on maximizing every microjoule.
Today, things look different. Protocols and standards boards have come a long way and are taking the next steps in optimizing these protocols to meet the demand.

“It forced us to rethink everything: low-power radio, multi-source harvesting, and storage that could handle total energy droughts. Then we had to make it scale to millions of devices.”

This experience makes one thing clear, successful energy harvesting is never just about a circuit. It’s about system-level design. A device that needs to survive weeks in darkness, or operate in unpredictable conditions, must account for not just average power draw, but extreme cases, like the days where no energy comes in. And that’s not easy. Especially not when security requirements now demand additional processing, storage, and compliance, all under the same tight energy budget.

Designing for the real-world, not the lab

In energy harvesting, conditions are never guaranteed. Whether powered by indoor light, outdoor sun, kinetic energy, or thermal gradients, what matters isn’t the peak power, it’s what happens on days when the expected harvested energy is not there.

Jeff Crystal, COO of Voltaic Systems, reinforced this reality from the power source side: “Energy is a probability,” Jeff said. “You can model solar input by location and time of year, but once you put a panel on a container or a cow, you introduce uncertainty; angle, orientation, weather, dirt. That’s what you have to design for.”

This variability fundamentally shapes every downstream component. Devices must store sufficient energy to survive days or weeks without new input. Storage solutions like lithium-ion capacitors or hybrid batteries need to be both rugged and efficient. Meanwhile, power management ICs (PMICs) must dynamically adapt to these changing conditions.

“Durability and adaptability go hand in hand,” Jeff added. “You need a system that performs the same in year ten as it did on day one.”

Every microjoule counts, in both hardware and firmware

While hardware platforms have evolved, they haven’t always kept pace with the needs of energy harvesting. As Tristan Cool from Silicon Labs put it:

“If semiconductors don’t follow, it’s all in vain. We can’t waste what harvesters fight so hard to provide.”

Tristan walked through how his team had to rethink the entire stack, choosing low-leakage process nodes, adapting DC/DC converters to emerging battery chemistries, and creating dedicated dev kits to support energy-aware firmware from day one.

“It used to be that we boasted about being great for battery-powered devices. Then along came a market that said: ‘We want to go battery-less.’ That’s a whole different challenge.”

These necessary improvements are now aspects that Silicon Labs considers in every new chip in their roadmap. It’s a market they cannot ignore. It is too vital for IoT scaling.

But Silicon Labs learned that empowering developers means more than just power-efficient devices, it means providing tools, reference designs, and firmware examples that reflect real-world harvesting use cases. Otherwise, engineers spend more time figuring out how to develop than actually building.

“If it takes 24 months to develop an energy-harvesting device, the market won’t wait.”

Assumptions kill battery life. Measurement extends it.

Throughout the discussion, one recurring point brought the entire system perspective into focus, none of this matters if you’re not measuring the right things. And that’s where Björn Rosqvist, CPO at Qoitech, brought a important reminder:

“You can’t assume what your PV cell will deliver. You need to test how it behaves when it’s dirty, shaded, scratched, because that’s the real scenario.”

Too often, devices are optimized under lab conditions, using datasheet values and synthetic loads. But real-world harvesting is nonlinear. Light varies. Orientation changes. Storage elements recover differently after stress. If a device isn’t validated under those conditions, its performance in the field will diverge.

Qoitech's tools helps engineering teams visualize real-world energy usage. This includes profiling PV cells under various conditions, evaluating storage charge/discharge performance, and correlating firmware execution with power consumption line by line. Allowing the tests of edge cases before deployment and providing the insights needed to meet power budget goals.

“It’s not just about hardware anymore. Optimization is a shared responsibility across the entire team.”

Boosting a low-power mindset that shifts from treating power as a post-deployment surprise to making it a first-class design variable to enable smarter tradeoffs, better component selection that results in longer-lasting devices.

Energy harvesting is ready to scale

Beyond the technical takeaways, the more profound message centered on how the industry is evolving and how more sustainable solutions are being demanded. What made this discussion particularly timely and encouraging was the sense that we're finally entering an era where all the necessary elements are coming together:

• Developers can build battery-less devices without reinventing the stack.
• Silicon providers are shipping MCUs with energy harvesting in mind.
• Power source vendors are designing for harsh, long-term environments.
• Measurement tools are bringing visibility into every part of the system.

This kind of ecosystem alignment is what allows energy harvesting to go from demo to deployment and scale to millions of devices. It reduces integration friction. It shortens development cycles. And, most importantly, it makes maintenance-free, autonomous devices a reality.

Watch the talks, keynotes and panel discussions from The Things Conference 2025 here.