ETIP Photovoltaics

Roadmap 6

“low-power” energy harvesting PV

PV together with small batteries can power wireless sensors or actuators, including in the home.

Rationale for support

Sensors or actuators in dim places (e.g. indoors, or receiv- ing only artificial or diffuse light) may be powered by a combination of a suitable PV cell and battery.


Mass-market PV technology, tuned to the solar spectrum and bright light, is not adapted to dim conditions. Current- ly, amorphous silicon PV is widely used for indoor and port- able applications with commercial efficiencies of around 10 % on devices fabricated on glass. Although compound semiconductors have achieved higher power efficiencies, their cost limits their commercial rollout for commercial products. New generations of PV technologies have shown great potential in harvesting energy in low light conditions and lab demonstrations up to 30 % efficiency values have been shown for artificial indoor illumination.

Targets, Type of Activity and TRL

Fabrication of large area device for demonstration of new applications powered by PV energy harvest- er such as IoT, remote sensing and home automa- tion applications (TRL6).
Bring the technology from TRL3-4 to 5 or 6 for PV technology on new functional substrates (flexible, paper etc).
Integration between different energy harvesting and with storage systems (TRL 6).
LCA analysis of internet of things or wireless sensor systems with and without indoor PV to understand benefits and limitations.
Encapsulation materials and designs for guarantee- ing product lifetimes (wide range of TRLs, from new concepts to utilizing existing ones for solar PV as well as that of electronics).
Bring together developers of PV technology, with storage, power, sensor, electronics developers, as well as operators of smart cities, smart products, and other stakeholders to develop better lower power electronic systems (TRL 6-8) and totally new concepts (TRL 1-3).


There is no specific standard for performance quantifica- tion under low-light conditions. The efficiency and hence the power density output is strongly dependent on the spectrum, especially since the calibration is usually done in lux. The variability of the light conditions implies the development of efficient electronics that could gather all the energy produced by the light harvesting system. At the same time, integration with a device integrated or system integrated storage element can provide the power conti- nuity needed in some low power applications such in IoT or remote monitor sensor. The pervasiveness of low pow- er PV energy harvesting requires green non-toxic material and an appropriate waste management/recycling. In this context, one can define some specific KPIs:

KPIs that can be utilised for capturing progress in the above identified R&I fields are:

KPITarget Value
Design and Fabrication

Identification of PV materials and PV architecture for the specific low power applications depending on the light intensity, light spectrum and application itself (2025)

Module/cell design and fabrication process that enables easy tailoring of the PV device to products specifications (2027)


Power and energy yield PV performance to meet application specific power and energy requirements (2027)

Reproducibly achieve 25 % efficiency or more over module level in the 200 lx-500 lx under white light illumination (2027)

ManufacturingCost of the PV energy harvester compatible/comparable with the cost of low power electronics (2027)