Ruud Ringoir, product manager at Kipp & Zonen is a regular visitor to PES. It’s great to hear that the markets continue to be buoyant. There is continuous research into optimizing their solar radiation measurement tools, which will spill over to the roof top market.
PES: Welcome back to PES Solar/PV magazine, Ruud, it’s great to talk with you again. I’m sure there will be some new readers, so could you begin by explaining a little about the background of Kipp & Zonen and the importance of the solar/PV industry to you?
Ruud Ringoir: Yes, my pleasure. Established in 1830 and manufacturing pyranometers since 1930, Kipp & Zonen has a long history as a leading manufacturer of accurate and reliable solar radiation sensors and systems.
We offer a wide range of radiometers from ultraviolet to far-infrared. Our market has long been meteorology and science, but over the last 20 years solar energy has become our main market. Product improvements and interfaces have optimized our monitoring solutions for this industry.
PES: Are you still finding this is a growing market?
RR: Yes, we have spent years explaining to solar energy customers the benefit of accurate solar monitoring, now we can focus on advising the most optimal solutions for their local situation.
This shows the market has matured and is now focusing on optimizing performance. The price drop in PV panels made it an attractive source of solar energy. The ongoing research, prospecting and performance monitoring is also still a growing market for us.
PES: Bifacial seems to be the new trend in PV, can you explain what it is and whether you are expecting this trend to continue?
RR: Bifacial is simply a PV module that makes use of solar radiation coming in on both sides, therefore the back is also transparent. When sunlight hits the ground or any other object it is reflected back, when the reflected light hits the back of the bifacial module it adds to its energy production. The relation between the incoming and reflected light is the so-called albedo.
Depending on the conditions the energy gain of bifacial modules can be 10% or more. To make optimal use of bifacial modules a high albedo, high DNI, optimal row to row distance and module height are required. This technology has been around for over 10 years but the latest improvements and pricing makes it possible to stand out, given the right conditions, over conventional one-sided PV panels. Tracking mechanisms have been optimized to work with bifacial modules and these technologies are often combined.
PES: Is it possible to monitor bifacial PV with pyranometers?
RR: Yes, to monitor a bifacial PV plant a double pyranometer (albedometer) is used in the plane of array, one facing up for global tilted radiation, the other facing down for the (tilted) reflected light. The albedometer existed long before the bifacial technology, because it is used in meteorology and climate research as well.
