SPF Institute for Solar Technology
The SPF Institute for Solar Technology was founded in 1981 and is part of the HSR University of Applied Sciences located in Rapperswil at the lake of Zurich.
Currently, 40 employees focus on various topics in the field of renewable energy technology and run an internationally accredited test laboratory.
Thermal insulation for collectors – SPF certification
Thermal insulation is one of the key components for a good collector. In addition to its thermal properties thermal insulation must be able to meet extraordinarily high requirements that go well beyond what is expected of "normal" insulation.
A key issue is out-gassing from binding agents: out-gassing from insulation is often one of the main causes of failure in collector tests.
Insulation generally contains binding agents and other chemicals. Modern collectors can easily reach temperatures of around 200 °C. At such high temperatures, substances decompose causing sediments to be deposited on the cover. In general these are visually disturbing and may also affect collector performances considerably, in particular where anti-reflex covers are used.
Compensators and collector connections – SPF certification
A solar thermal system’s operational safety and life-span depend heavily on the quality of the components employed. From this point of view, compensators and connections have emerged as particularly weak areas. Generally any malfunctions in these areas result in serious damage (system leakage).
Components must be reliable and in addition, easy installation and affordable manufacture are increasingly required.
For this reason SPF has developed a special certification programme intended to evaluate the particular stresses connections are subjected to in solar thermal operations. The programme involves the simulation of both the thermal shocks and mechanical stresses that are to be expected over a minimum life-span of 20 years.
Solar glass – Certification
SPF has developed two certification procedures specially tailored for solar glass. These procedures include special requirements with regard to the optical properties of solar glass for the two specific applications.
Solar Thermal collectors (ST):
Glass as a transparent cover of insulated solar thermal collectors with a selective absorber.
PhotoVoltaic modules (PV):
PV modules composed of cells made of crystallin silicon directly laminated to the solar glass.
For the purposes of a certification adapted one of the above mentioned application, solar glass is graded into different performance categories according to a specially defined glass efficiency value ηGL,ST or ηGL,PV. The following factors are taken into account in the determination of the aforementioned glass efficiency value: optical transmission, incident angle modifier and degradation (transmission reduction due to environmental factors), which are measured and rated according to the specific application. The idea behind it is that when a glass is replaced with another glass in the same performance category no loss of performance should be experienced in the collector or the module.