Frequently Asked Questions
Corporate
How can indoor solar cells solve future IoT power challenges?
IoT deployment is accelerating, increasing the number of wireless low-power devices across industries. Powering this growing volume with disposable batteries creates significant challenges in cost, maintenance, and sustainability.
Indoor solar cells (indoor photovoltaics) offer a scalable alternative by capturing ambient indoor light and converting it into continuous power.
Why does Epishine focus on indoor solar cells?
Most wireless low-power electronics operate indoors, where light levels are significantly lower than outdoors. Traditional solar cells are designed for direct sunlight and perform poorly in low-light conditions.
Epishine develops indoor solar cells (indoor photovoltaics, IPV) specifically optimized to capture low indoor light efficiently. Our technology delivers reliable performance where most other solar cells generate very little power.
Epishine combines low-light optimized advanced photonic materials with roll-to-roll manufacturing — enabling a new manufacturing paradigm for electronics: scalable, cost-efficient, and sustainable.
Where are Epishine indoor solar cells manufactured?
Epishine’s indoor solar cells are manufactured in our facility in Linköping, Sweden.
What is the difference between indoor and outdoor photovoltaics?
An indoor photovoltaic (IPV) cell works according to the same fundamental physics as an outdoor solar cell. The key difference is the type of light and the intensity of light it is designed to capture.
Indoor lighting contains only visible wavelengths, while sunlight also includes large amounts of infrared. Because of this difference in spectrum, indoor PV uses semiconductor materials with slightly higher bandgaps, which are better at converting visible light, whereas outdoor PV uses materials optimized for the full solar spectrum.
The intensity of light is also different. Indoor light is about 1,000 times weaker than sunlight, meaning an indoor cell generates extremely small currents. Outdoors, large currents make resistive losses a major concern. Indoors, resistive losses matter far less; instead, the tiny photocurrents must compete with equally tiny leakage currents caused by microscopic defects in the PV device. Minimizing this leakage current is therefore one of the most important goals in indoor PV design.
Since the light conditions are so different, the efficiency of indoor and outdoor solar cells cannot be directly compared. Indoor cells may show higher relative efficiency, but always under much lower light levels.
What certifications do Epishine’s indoor solar cells have?
When was Epishine founded?
Where is the Epishine team located?
Epishine’s headquarter and production are in Linköping, Sweden, with R&D located on-site to support continuous innovation. Our team includes seven PhDs and represents 17 nationalities worldwide.
Light Energy Harvesting
What is ambient light?
Ambient light is the general background light present in an environment. Indoors, it includes artificial lighting such as LED or fluorescent lamps, as well as natural daylight entering through windows and light reflected from surrounding surfaces.
Indoors, ambient light typically ranges between 50 and 500 lux, which is significantly lower than direct sunlight, which can reach around 100,000 lux.
What is energy harvesting?
Energy harvesting is the process of capturing small amounts of energy from the surrounding environment and converting it into usable electrical power. Also known as power harvesting, ambient energy harvesting, or energy scavenging. Energy harvesting enables low-power electronic devices to operate without disposable batteries or wired connections.
One common form of energy harvesting is light energy harvesting, where ambient indoor light is converted into electrical power using organic photovoltaic cells.
Read more:
What is the minimum light level required for indoor photovoltaics?
Epishine’s organic solar cells are designed to operate efficiently in extremely low light conditions, starting from just 1 lux, which is comparable to the light from a candle.
However, an indoor solar cell must generate enough power to meet the energy requirements of the device it is intended to power. This depends both on the device’s power consumption and on the available light levels in the environment. Contact us for more details on your specific application.
What is light energy harvesting?
Light energy harvesting is the process of converting light into electrical power using photovoltaic materials. In indoor applications, ambient light from sources such as LEDs and fluorescent lamps can be used to power low-energy electronic devices.
Materials
What does "organic" mean in organic solar cells?
What is the semiconductor in organic photovoltaics?
What materials does the Epishine indoor cell consist of?
Epishine Indoor Solar Cells
What is photovoltaics?
What is indoor photovoltaics (IPV)?
What is the power output of Epishine indoor solar cells?
The power output depends on the light intensity.
At 500 lux, which corresponds to typical office lighting conditions, our indoor solar cells deliver up to 22 μW/cm².
For the latest performance data at different light levels, please refer to our updated datasheet.
What is the difference between Epishine OneCell and Epishine MultiCell?
Epishine's indoor solar cells are available in a selection of sizes and formats, adapted for different applications. To meet different voltage requirements, Epishine offers two product categories: Epishine OneCell and Epishine MultiCell. Both are based on the same basic technology but differ in how the voltage is adapted to the application. Each individual cell provides an output voltage of approximately 0.5 V. Epishine MultiCell uses multiple cells connected in series to achieve a higher voltage, while Epishine OneCell consists of only one coherent cell that provides a more homogeneous surface.
Depending on the application, the solar cell can also be combined with a PMIC (Power Management Integrated Circuit) for better voltage matching and energy management. This enables adaptation based on both the requirements of the electronics and the desired system architecture.
What sizes of indoor solar cells does Epishine offer?
What is the lifetime of the indoor solar cell?
How do you recycle Epishine organic photovoltaic cells?
Consult regional regulations before disposing of any electronic device or component.
If Epishine indoor solar cells are part of an electronic device, the electronic device shall be handled in accordance with applicable regional regulations for handling electronic waste.
Epishine solar cells can be recycled through energy recovery processing. While Epishine cells can in general be regarded as household waste and handled according with applicable regional regulations for handling household waste, consult regional regulations before disposing of any product.
What is the difference between indoor photovoltaics and indoor solar cells?
What are the benefits of powering electronics with ambient light?
What is a bifacial solar cell?
A bifacial indoor solar cell (indoor photovoltaic, IPV) is designed to capture light from both sides. This unique feature boosts performance by up to 80% compared to the specifications in our data sheet when illuminated from both sides.
Bifacial solar cell integration example.
