Heating and cooling account for around 50% of Europe’s final energy consumption, making renewable heating and cooling technologies a significant lever to reduce carbon emissions. One well established renewable heat technology is solar thermal. Solar thermal systems use solar radiation to heat a working fluid directly, providing a low-cost heat source with a significantly better specific yield per unit of collector area than PV. Solar thermal collectors have been used to supplement domestic hot water heating for decades, but more recently the market for large solar thermal arrays to supply bulk heat to district heating systems or industrial customers has begun to grow significantly. At present long-term monitoring of these systems is carried out using a variety of proprietary tools developed by industry stakeholders – with limited agreement on methodology and little transparency on the algorithms being employed – or not at all. To address this, the international standard ISO 24194 was published in 2022, providing an open standard for the assessment of the performance of solar thermal arrays in operation. The SunPeek project is the first open-source implementation of this standard and aims to become the reference implementation by providing an open, trusted, user friendly application with well documented design decisions in cases where the standard is ambiguous. SunPeek is designed with highly automated workflows in mind and includes robust data preprocessing and error checking. It also includes several extensions of the ISO methodology to allow valid assessments to be made under a wider range of operating conditions, and funding has been secured to add fault detection, localization and remediation decision support functionality.

Several use cases are cases envisioned including:

Long term automated regular performance assessment.

performance guarantee verification (a use case which clearly demonstrates the value of being open source, due to verifiability of the codebase)

Research applications

Integration into existing fully featured plant monitoring solutions.

Different interfaces and packaging formats are provided to support these.

The core functionality is written in python, and made available as a package on PyPi (https://pypi.org/project/sunpeek/).

A set of docker images and a compose configuration allow deployment as a web application with Vue.js based user interface and FastAPI based REST API.

The project is hosted on GitLab (https://gitlab.com/sunpeek), documentation is at https://docs.sunpeek.org and a demo is available at https://demo.sunpeek.org.

This work has been supported by the Austrian Research Promotion Agency (project HarvestIT, project number FFG 887648, and IEA SHC Task 68, FO999890460) and the European Commission (project IndHeap, proposal number 101136140).