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UK startup develops high efficiency solar cells for the IoT

Technology News |
By Nick Flaherty


Lightricity is using an inorganic crystalline compound semiconductor on a range of substrates to produce high efficiency solar cells that work with indoor lighting for IoT applications.

It has teamed up with solid state battery developer Ilika and energy harvesting chip maker e-peas on reference designs for its rigid cells.

“What Lightricity offers is a new, very efficient light harvesting technology particularly for ambient lighting,” said co-founder Mattias Kauer. “The advantage of our technology is that it is 3 to 6x more efficient than that currently available to product designers. There are some other advantages with a higher output voltage as you don’t need to boost the voltage and a high dynamic range with the light levels that can work from 10 lux to 1000 lux.”

The efficiency is flat across the light range from 30 to 35% depending on the type of lighting, from white LED or fluorescent with different light temperatures. “This is a consequence of the material and device design that we have developed as our core technology,” he said. “We can use various types of substrates including silicon – we use a semiconductor facility, that’s all we can say.”

“A flexible substrate is on our roadmap and we have R&D samples but there isn’t the production equipment to make it in volume. It’s possible but it will be some time before it’s in production and that’s where the additional investment is required,” he said.

“The material is very stable so we can use various types of packaging depending on application,” said Mathieu Bellanger, CTO of Lightricity. “It is typically encapsulated with epoxy, that’s a typical way of doing it, but we can tailor that depending on the customer requirement.” The company recently worked with sensor maker GSS and Ilika on an energy harvesting wireless CO2 sensor demonstrator for the home. 


The technology was developed at the Sharp R&D lab. “We have discussions with angel investors but we are fortunate that the technology development has been done so we can take the business forward with early prototype sales and development contracts with customers,” said Kauer.

“We have a small pilot production line and are working with customers to design it into their products and that enables us to ramp up our volumes. In time that will lower the cost so ultimately we will have mass production and be a mass market supplier,” he said.

The key focus is on commercialisation. “We can improve the technology in term of performance a little bit further but most of the development has been done and the focus now is on the production ramp up and customisation, for example in reducing the thickness and adapting the shape, as well as reducing the cost of manufacturing,” said Bellanger.

“There’s no restriction on panel size as such, 1cm2 to several cm2, but this is not for large scale power generation for outdoor but for mobile or asset tracking and other IoT applications where the device or package size is a few cm,” he said.

“In all practical systems you will need a storage element for buffering to provide a peak current for a wireless module or buffer for a period of darkness for continuous operation, that’s very typical for energy harvesting use cases and we have designs with all the storage elements from lithium ion coin cells to ultracapacitors,” he said. “We are working closely with complementary technology developers such as Ilika solid state batteries and we also work with several power management providers. One of them, e-peas, has already adapted their design to make it work well with our device with the input voltage and a maximum power point tracking (MPPT).”

“We have a reference design with a commercial off the shelf IC and storage elements that are already available so there’s no barrier to bringing it to market but there are additional gains to be had,” said Kauer.

www.lightricity.co.uk

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