Greenbuddies tips – June 2021

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The spa season begins…

The improving weather and the pandemic situation are reflected in the slow return of normal things to “normal”. As a result, hotels and spa complexes are starting to reopen. We’ve decided to take you to one such complex project in a slightly different way than you’re used to – today. And, of course, it’s going to be a “Greenbuddies Charging” style visit.

This time, we’ll be talking about a complex project to install a photovoltaic power plant with an installed capacity of 1.5MW on shelters (or carports if you prefer) in the public car parks in the area of the Sonnentherme Lutzmannsburg spa. EPC stands for Engineering, Procurement & Construction, which is a turnkey construction project including the preparation of the project documentation, the purchase of all technologies, components and services, the actual implementation and construction, and finally the commissioning and handover to the client for use.
The main purpose of the project is to reduce the own-consumption of the entire spa complex and at the same time to expand the charging capacity for parking electric cars or plug-in hybrids when visiting the spa. To the one existing charging station, a total of 10 AC chargers with a unit charging power of 11kW will be added thanks to Greenbuddies Charging.
Let’s take a brief look at the history of the project: after nine months of negotiations, Greenbuddies Charging signed a contract with the general contractor, E-Koenig, based in Bad Vöslau, at the end of 2020. The subject of the contract is the complete supply, assembly and installation of the aforementioned technologies and solutions for the largest reference solar power plant project of its kind located on carports in Austria. With a bit of exaggeration, the parallel can therefore be drawn that Austria’s longest spa slide (202m) will be joined by the largest solar power plant built on a massive carport structure on both car parking areas on the site.
As the project is subject to the Obenpullendorf building authority in terms of location and compliance with all legal conditions, it was necessary to prepare the documentation for the building permit in the first phase of the project so that the project could be implemented. Due to the very specific conditions or natural constraints of the car parks underground (e.g. a maximum water table height of 90cm below the surface and at the same time a clay subsoil at a depth of only “100cm”, which does not allow rainwater drainage from the roofs of the carports and the car park surface itself in a standard way), we had to add an extensive construction part to the actual PV project and charging solution for electric vehicles. This was primarily a drainage system under both car parks in the form of a retention basin and a soakaway layer that can hold all the rainwater or water from melting snow, thus ensuring safe year-round operation of the car park. The system required the Exchange and recycling of a total of 5,000 m2 of grass tiles and their replacement with paving stones in all parking spaces.

In addition to the above drainage system for both car parks, the scope of the project also included the refurbishment of the surface of the bus parking area, again including drainage, the construction of shelters (the method of hammering HEA180 profiles and laying 72 concrete blocks was used for the installation of the foundation structure) with PV on the roofs of the carports. In the construction of the power plant we used 11 pieces of Huawei 110kW inverters, the infrastructure for charging the electric vehicles consists of 10 pieces of AC chargers with 11kW power. This included the supply and installation of a CCTV surveillance system, a lighting system for the interior of the shelter structure and separate control of the entrance barriers, as well as cabling for the UPS backup power supply.

By the time our readers read these lines we will already be preparing to install the horizontal structures and laying the panels on the roof of the carports. The finalization of the entire work and handover to the investor is planned for the beginning of the fourth quarter of this year.

So keep your fingers crossed!

Unconventional sites for the construction of photovoltaic plants – Greenhouses

In recent years, the number of photovoltaic power plant constructions has grown rapidly, meaning that the possibilities on conventional construction sites such as fields and roofs are gradually being exhausted. The industry is becoming increasingly interesting for us due to the requirements of novel locations for placing of solar plants.

In past articles we have described atypical locations for the construction of solar power plants including former landfills, roofs of shopping malls and sports stadiums. Currently, we would like to talk about projects implemented on the roofs of greenhouses. These are atypical buildings that must be designed individually as a result of specific requirements imposed on these projects. One of these interesting requirements is, for example, the required brightness in the greenhouse together with sufficient sunlight fall on the panels located on its roof. In this way, an ideal performance of the panels can be achieved. Another requirement may be, for example, impermeability against rain so that the greenhouse is fully usable.
An interesting solution is a structure that is able to transmit solar radiation through the panels themselves, as they are partially transparent modules. To give you an idea, these modules are shown in Figure on the right. We have not yet had the opportunity to come across this type of solution because it is not yet commonly used in commercial projects. However, it is certain that in the very near future a rapid development of this type of project can be expected due to the high demand alongside strong support for innovation in this field. In a new study in March 2021, researchers at North Carolina State University tested the application of semi-transparent modules in a greenhouse, monitoring the effect on plant health and growth inside after installing panels instead of glass. In red lettuce, it was shown that the use of semi-transparent solar panels did not affect plant growth. The type of solar panels used in this research are semi-transparent organic solar cells (ST-OSCs), not the silicon-based type used in large photovoltaic plants. ST-OSCs promise flexibility and can be modified to absorb different wavelengths of light as needed. These are, wavelengths that plants do not use for photosynthesis. So far, these panels do not have the same performance as conventional photovoltaic cells. However, they are constantly improving and could be used in many different applications, including windows of residential houses.

Our first experience in this field was the Seelow photovoltaic power plant in eastern Germany, where we were in charge of the complete installation of the PV plant. Therefore, the work included the assembly of substructures, modules, electrical installation and inverter assembly. This project has a capacity of 750 kWp – 2,628 modules and 11 inverters were installed during assembly. In this project, the greenhouse glass was left intact and the modules were installed only on the south side of the roofs, so this site continues to function normally as a greenhouse.

Interior view of the construction process (before-after).


The latest greenhouse PV power plant construction we provided is located in the north of the Netherlands and was successfully commissioned a month ago. This power plant has a capacity of 6 MWp and is one of the largest of its kind. During its construction, around 20.000 modules and were installed. Unlike the German project, our customer in this pilot project opted for a mounting system that required the removal of glass from the greenhouse roofs. The first challenge for our customer was to remove the glass. Then the metal profiles were installed (bespoke developement by the customer) and the last step was the assembly, panel connection and DC wiring work. Due to the specifics of the project it was always necessary to have, in addition to standard machinery, special platforms normally used for greenhouse construction. The construction work lasted approximately 2 months and we are very happy to have been part of this great technical challenge and part of its successful start-up. We believe that this interesting use of solar modules will become more frequent as this solution brings only positive aspects.

Aerial view of a completed 6 MWp power plant project in the Netherlands.

New Project Manager Michal Boška

The Board of Greenbuddies is constantly expanding with quality people and we decided to introduce our new project manager Michal Boška in a short interview.

1) Tell me how you first got involved in with Greenbuddies?
I found out about the existence of Greenbuddies by coincidence, specifically through spotting a hiring advertisement on a platform. Therein, Greenbuddies presented itself as a dynamic, flexible and goal driven company. Furthermore, it displayed all the values I was searching for, thus I considered that an application was worth a try. The try worked, and here I am.
2) What do you find most challenging about jour job?
My job position is in its very nature a challenge ? Project development is a complex, complicated and challenging environment- requiring the same from his manager. The most challenging situations are when everything is perfectly prepared, checked and planned but subsequently the action of one individual destroys this all effort within the fraction of time.
3) What’s your personal philosophy on what should be done about Renewables/Solar industry?
Despite the fact that there are certain problematic topics in the solar industry, I believe the work we do today changes our future. For me personally, it is a sector with greater added value alongside social, planetary, and environmental significance. It may seem utopic that PV industry has the ability to change everything, but it will definitely slowly contribute to better and cleaner future, even though the path ahead of us is still long.
4) What would you tell someone who is thinking about building a PV plant?
That the solar energy is definitely worthy of investment, that it has reached great milestones in development over the last decade, it is a step forward to a clean future and one of the core methods of sustainably generating electricity. Daily usage of electricity in our lives is enormous and continuously growing. In order to keep our current way of life without destruction of the environment, everyone needs to turn his interests into green energy production. A solar plant is a power source affordable to almost everyone today.
5) What do you do when you aren’t working?
Spending time in nature with my wife and daughters, lost in woods by myself and surrounded by mountains with my hiking buddies.