Improving agrivoltaic systems performances with spectrally selective solar cells 

About the project

Sweden has set the highly challenging targets of achieving 100% renewable electricity by 2040 and no net greenhouse gas emissions by 2045. Nevertheless, the current installed PV capacity is far below the planned capacity required for a fully renewable electricity system of about 10-30 GWp by 2050. Despite a clear market trend in installing utility-scale ground-mounted PV systems, the Swedish Government does not have any investment subsidies for solar parks or solar systems.

The installation costs for utility-scale PV systems are significantly lower than those of distributed commercial or residential PV systems, and the system optimization can guarantee higher energy and economic performance. Typically, large-scale ground-mounted PV systems are installed on agricultural land (i.e., arable land or pastureland) for the easiness and cost of installation. Nevertheless, installing PV systems on agricultural land has received several criticisms, mostly related to visual impacts and ethical reasons connected to land use for energy purposes rather than for food production.

There is a conflict between SDG 2 "Zero Hunger", and SDG 7 "Affordable and Clean Energy", and SDG 13 "Climate Action". Agrivoltaic systems represent an answer to this SDGs' "conflict". An agrivoltaic system combines PV production with standard agricultural practices using unique PV supporting structures and cutting-edge technologies such as bifacial PV modules or wavelength/spectrum selective solar PV modules. The concept behind agrivoltaic systems is to minimally interfere with cropping production while guaranteeing electricity production on the same land. In most of the research conducted on open-field Agrivoltaic systems, silicon-based solar cells are used (i.e., in monofacial or bifacial PV modules). To guarantee less shadings and lower impact of shadings on the crop yield, silicon-based PV modules with a lower density of the solar cells can be employed.

A further research and market trend is to implement new solar cell technologies such as wavelength/spectrum selective solar cells that selectively absorb specific wavelengths of the solar spectrum while allowing other wavelengths to be transmitted. The use of this new key technology for combining solar electricity production and crop production has been so far limited to greenhouse applications. This proposal aims to fill this research gap by establishing a small-scale open-field APV based on semi-transparent wavelength/spectrum selective solar cells that will complement the already well-established first APV in Sweden installed at Kärrbo Prästgård.

Purpose

The main purpose of this project is to enhance the knowledge on how semi-transparent spectrally selective PV modules, typically used for building integrated projects or greenhouses, can be used and affect the performance of open-field agrivoltaic systems. This will be accomplished by developing and validating a unique tool for the simulation, optimization, and optimal design of agrivoltaic systems integrated with semi-transparent spectrally selective PV modules.

Project goals

The main purpose and the main research questions of this project will be attained/answered by two specific objectives:

• establishing a small-scale agrivoltaic system based on spectrally selective solar cells at Kärrbo Prästgård
• substantially improve the model developed in our previous studies to perform techno-economic simulations and optimizations of agrivoltaic systems based on spectrally selective solar cells.
  

Activities

The main methods applied in this proposed research project will consist of:

• performing a literature review concerning the use of spectrally selective solar cells for agrivoltaic applications
• interacting with the project supporters to better understand the industrial and agricultural needs
• establishing a small-scale cutting-edge experiment
• developing our cutting-edge model to be able to perform simulation and optimization of agrivoltaic systems based on spectrally selective solar cells.