Startup factory Technopark in Winterthur (Switzerland)
Retirement home Eichgut in Winterthur (Switzerland)
Residential building Mattenbach in Winterthur (Switzerland)
Factory yard Werkhof Scheidegg in Winterthur (Switzerland)
Energy green roof realised by business partner Fenaco in Winterthur (Switzerland)
Energy green roof realised by business partner BLDVEG in Hanaton (Israel)
Energy green roof realised on a school building in Sosnovka (Kyrgyzstan)
Energy green roof realised on bus shelters in Zurich (Switzerland)
Energy green roof realised on pump station in Sudogda (Russia)
The microclimate on the roof and the ground close to the building are different. The urban heat effect is much higher on the roof; it directly affects the vegetation growth, evapotranspiration rate of soil and plants, plants resistance to heat and prolonged drought periods, PVs efficiency and productivity in time. We should face all these highly stressful conditions to which plants are exposed; we need to create smart innovative solutions to fight extreme climate events, that getting more and more dangerous in the urban environment.
Werkhof Scheidegg Test Roof (2013-2015)
With the collaboration of the Zurich University of Applied Sciences (ZHAW) the classical installations have been tested for 3 years on the cooling effect of the flat versions of 15 and 20 tilts modules from Germany with subsconstruction from ZinCo. The research was conducted from 2013 to 2015 when millions of data were collected and analysed. The final result has demonstrated that the cooling effect of 3 °C on the roof improves the productivity of classical PV installations by only 0,7 %.
Moreover, we studied the layout of the energy green roof and the reaction of the gravel of the system, applying different types of substrates on different substrate layers.
The cooling effect on classical installations is only 3 °C – it is less than 1 % of the higher productivity of PV modules.
Technopark Test Roof (2016)
The startup factory Technopark in Winterthur is the place where you can bring your innovative ideas to life. Our energy green roof brought to life in 2016 is only a showcase, but it was the first time when the idea for the realisation of vertical PV installations came to life. Moreover, it was the first energy green roof with vertical installations where we continued studying the cooling effect of green roofs on PV modules, additionally to the energy production of different sub-constructions and classical commercial flat installations in typical East-West positions.
Nonetheless, it was just the showcase we could jump on to the next level to start realising this system on a larger scale. It wasn’t possible without the collaboration of our partners – Solarspar and ZinCo.
In addition, to the cooling effect we researched energy production of different sub-constructions of PV installations with classical PERC cells made by Solarspar such as Est-West vertical installations, East-West butterfly installations with an inclination of 15-30 degrees, classical 10 angle degrees flat installations (North-South and East-West).
The Est-West classical flat modules were installed to optimise the use of the roof. They were put directly on the ground, instead butterfly and vertical were installed about 20-40 cm over the ground. For this energy green roof, the classical build-up from ZinCo was implemented and integrated with butterfly and vertical installations.
Eichgut Test Roof (2019)
It was our first big energy green roof project realised on the retirement home Eichgut in the Swiss city of Winterthur, described in the BBC article “Urban oases combine roof gardens and solar panels” in 2019, which came around the globe. ZHAW took part as the research partner in this project. Solarspar is a contractor for the PV installation, but the modules were manufactured by Megasol as well as by Meyer Burger AG. The company Growsolutions by A777 participated in the installation of the energy green roof in combination with vertical PV modules, where the substructure was designed, produced and provided by ZinCo AG.
We used this energy green roof as a research roof to test the reflection effect of the albedo of such materials as gravel, darker-lighter topsoils and surfaces, a variety of soils like recycled soils and classical type, and silver-leaved plants.
Mattenbach Test Roof (2021-2024)
Our biggest project of this green energy roof began in 2021 where the research on cooling effect of PV installations by green roof was conducted for 3 years up to 2024. This residential building located on the Mattenbachstrasse in Winterthur (district N7), has already shown wonderful results on rooftop gardening in combination with different PV installations and substrate types. The total installed capacity of PV installations is 93 kWp. The different amount of Verora AG biochar was added to the substrate like an additional soil amendment. The goals of this experiment varied from the quality of green vegetation coverage to the rooftop gardening which showed amazing results!
On this research roof, different dark- and light-coloured materials have been tested for direct and indirect light reflection (albedo effect) that increases the efficiency and productivity of PV installations. Silver-leaved plants also play a role in the reflection of sunlight. We need them as the necessary piece of the urban mosaic in the whole system.
According to Green Roofs for Healthy Cities, the albedo effect on the green roof varies from 0.25 to 0.3, but the white roof has a higher albedo effect of up to 0.65. In some cases, the weight of green roofs is too heavy for the construction of the building and the roof load capacity of it is limited. However, the white roof can be a solution, especially for retrofitting. It will reduce the UHI effect and the energy consumption of the building.
On the Mattenbach Test Roof, three types of modules from the manufacturer Hevel were used in different configurations:
▪ 34 pieces of 330 Wp with HTJ: 60 cells. Butterfly monofacial portrait (15° tilted).
▪ 113 pieces of 390 Wp bifacial: 72 cells. Vertical and Butterfly (15° tilted).
▪ 148 pieces of 255 Wp bifacial: 48 cells. Vertical bifacial portrait (90° tilted).
The microclimate on the roof is also one of the pieces of the puzzle which should be taken into consideration before designing a project for the green roof. Environmental variables such as radiation, temperature, humidity and wind — provide meaningful indicators for habitat selection and other ecological activities. We measure microclimatic parameters, including solar radiation, surface albedo, temperature, the rate and intensity of rainfall, wind speed and direction. The precipitation tendency of the region, temperature and sun exposure of the roof are the main criteria for the selection of plants.
Mattenbach report “Entwicklung und vergleichender Test eines Gesamtpakets für bifaziale PV-Systeme auf Gründächern” (December 2024).
- The system retained up to 73,890 liters of rainwater. Around 74 l of rainwater can be stored on the entire roof surface of 1000 m2. The increase in accumulation of rainwater on the roof reached 25-30% more (25% – 18,5 l/m2) with the additional supplement like a biochar/charcoal.
- In total 35 beetle species and 85 plant species were recorded, including rare and moisture-loving species. Vulnerable flora: Achillea tomentosa, Hieraricum tomentosum, Dianthus gratianopolitanus.
- Vertical bifacial PV systems achieved 70–95% of the energy yield throughout the year.
Our last report:
Sosnovka’s Test Roof (2022)
The project was realised on the school’s roof for handicapped children in 2022. The system contains vertical and south-oriented PV installations with a capacity of 6,72 kWp. In the same year in December, keepers held an opening ceremony.
Sudogda’s Test Roof (2021)
This project was realised in 2021 on the roof of the pump station for the sludge wastewater treatment. This building, built back in the 70s, has 2 types of PV installations: vertical and 35° tilt angle facing south PV installations with an installed capacity of 6,72 kWp. In the same year, an opening ceremony was held by the Swiss ambassador Krystyna Marty Lang.
BLDVEG’s Test Roof (2023)
This energy green roof was realised on the residential building in 2023 by a business partner BLDVEG in Hanaton (Israel). This pilot project has vertical installations of the installed capacity of 9 kWp (16 modules of 545 Wp bifacial modules) installed in March 2023 already on an existing green roof.
Fenaco’s Test Roof (2023)
This energy green roof of the commercial building in Winterthur is the combination of vertical PV installations and a green roof has installed capacity of 4,5 kWp (18 modules of 260 Wp bifacial HJT modules). Test field by the business partner Fenaco cooperative in Winterthur was used to study the albedo effect of the topsoil and silver/grey-leaved plants. The project is realised by Growsolutions.