Quick Q&A: a new approach for solar-powered windows


pv magazine: Solar-powered glass and windows are not necessarily a new technology, so what makes Physee’s PowerWindows unique?
Ferdinand Grapperhaus:
We sustainably innovate without compromise. Meaning that you do not see anything in plain sight. No wiring, no semi-transparent cells, and no colored dyes.

Are the PowerWindows fully bespoke and scalable?
Yes, at this moment our PowerWindow is fully modular and can be ordered in all sizes and shapes to fit all types of buildings.

Can you shed some light on the type of solar cells used? Are they the typical mono- or multi-crystalline cells found in a typical solar panel?
We are currently using 24% efficiency monocrystalline cells. However, the PowerWindow2+, which we are developing, will have a luminescent coating added, which needs CIGS or other large bandgap cells.

What would be the yield/output of a typical family home or commercial building fitted with these windows?
Physee is currently installing 1,800m2 of PowerWindows in a residential tower in Amsterdam. This is the equivalent of 100m2 solar panels. So this opens up around 150m2 of extra roof surface where the developer can now build a roof terrace to increase property value.

Tell us a little more about the first installation at Rabobank. How large is the installation, how has it been received and how does the bank and bank staff benefit?
The Rabobank project was our pilot and is now fully operational. The staff, however, will begin using the building from November onwards. Our second project is for the Netherlands’ Postcode Lottery for whom we installed 100m2 on the south facade last week. Their employees can charge USB(-C) devices directly on the windows while enjoying the view.

What do future iterations of the technology look like? How does the introduction of thulium improve the efficiency and performance of the PowerWindow?
The introduction of Thulium will triple our product's efficiency. That is why we are putting the larger part of our R&D budget into it. So each project we do now we fully re-invest any margins into our R&D. This means that each customer actively contributes to sustainable innovation of the built environment without compromise.

Have you explored the idea of energy storage or grid feed-in, or are the PowerWindows more effective as a direct self-consumption feature?
This topic is always on our mind and is always part of the conversation with the customer. I would have to tie this into my vision regarding a successful energy transition in general. I strongly believe that de-centralized grids, with smart balancing models and different types of storage and powe rproduction (BIPV) form a large part of the solution. Within this part of the solution I strongly believe in DC-grids because of local consumption.

Right now, we imagine self-consumption on the facade. You have many electricity-hungry products in building facades nowadays. I also see the proliferation of a DC-Grid, to eventually use the electricity somewhere in the building as DC. However, society and the market isn't at this point yet, but will be in the coming years. Lastly, we also offer the solution to deliver back to the grid.

In which countries is Physee hoping to introduce the PowerWindow? Do you foresee interest across Europe, particularly in the residential markets? Or are you focusing solely on commercial applications for now?
Our key markets are China, United Arab Emirates, the U.S., southern parts of Africa and South America, in that order. We are focusing mainly in regions where there are a lot of high rise buildings. If you want to make the built environment energy neutral, high rises do not offer a great deal in terms of roof surface, but they do have very large facades.

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