Part 1 Photovoltaic Installations: It was found that three important factors for how a fire can develop in a facade with photovoltaic installations are:

• the distance between the wall and the photovoltaic modules,
• whether the photovoltaic modules are built with glass on one or both sides, and
• what other combustible materials are in the cavity.

Experiments with modules with monofacial glass (with exposed plastic on the back) and the smallest cavity (6 cm) produced the most intense fires. With increasing distance, the modules tolerated more heat from the initial fire and released less heat when they ignited. The same effect was found when switching from modules with monofacial glass to modules with bifacial glass (glass on both sides). It was found that increasing the cavity distance by 4-5 cm has the same effect as switching from monofacial glass modules to bifacial glass modules.

Part 2 Plants: When establishing green facade systems on the facade, one can choose between different products and solutions. Some of the systems are designed to be mounted on the existing facade, while others can be used as a replacement for the facade and thus function as the building's climate shell. On the market, there are both systems that meet class A1 or A2,s2,d0 according to EN 13501-1 and systems that have no fire classification at all. In addition, the plants and the physical extent of the greenery system can affect fire safety.

Experiments with the combustible green facade system showed both falling burning parts and burning droplets. The fall of entire modules from the plant system helped limit the upward spread of fire in the plant wall. However, the building wall was directly exposed to flames when the modules fell, and if the wall had been combustible and caught fire, this could contribute to further fire spread upwards in the cavity. Both falling burning parts and burning droplets can be a possible mechanism for downward fire spread. Additionally, this could cause problems for firefighting efforts or for evacuation and rescue from the building if burning debris falls near doors or other escape routes. Therefore, the placement of green facade systems should be planned so that potential falling debris does not cause the mentioned problems.

In the conducted experiments with the non-combustible green facade system, the measured temperatures on the wall surface were not high enough to pose a risk of ignition there. Nor would there be a risk of ignition for a neighboring building under the conditions used in this experimental series. However, fire in the plants in a plant wall has been shown to give short bursts of intense fire (high heat release rate), and we cannot therefore rule out fire spread to neighboring buildings under the right conditions.

Testing and classification for both systems: For both photovoltaic installations and green facade systems, it is challenging to conduct the necessary tests for classification according to EN 13501-1 in a relevant manner. Especially for green facade systems, the living plants mean that the fire properties change over time.

This study is funded by the Norwegian Directorate for Civil Protection (DSB) and Norwegian Building Authority (DiBK). Part 1 of the study on photovoltaics was carried out in collaboration with the Fire Research and Innovation Centre (FRIC) and the Danish Institute of Fire and Security Technology (DBI).

You may find the full report (pdf) in Norwegian with English summary here: https://risefr.com/media/rapporter/ebob-fasadar-med-planter-eller-solceller-eksperimentell-studie-av-brannspreiing-i

The study has also been presented in Norwegian in a webinar. The recording can be seen here: https://www.youtube.com/watch?v=38Qw22iqXlo&t=602s