Puzzling with PV panels

To increase sustainability, Magentazorg had more than eight hundred solar panels installed on the roof of Oudtburgh residential care facility in Bergen. The project is unique due to the logistical challenges of the location and the innovative solution to maximize energy yield.

Edwin van der Vlist supervised project Oudtburgh from Generation Green. 'We are a renewable energy project organization. We deal with large solar panel projects, battery systems, and management systems around them. Oudtburgh was a great job for us. This project is unique because of the logistical challenge during construction, but also because of the product choice. The application of SolarEdge Power Optimizers ensures optimal results with these special roofs.'

Sophisticated string design

'The installation of the system took two months,' Van der Vlist continues. 'SolarEdge advised us at the product level and with the preparation of the project. They made an expected yield calculation, including annual energy generation and CO2 savings.'

Humfrey Disco of SolarEdge is manager of commercial technical marketing for the Benelux region. 'SolarEdge is a world leader in smart energy and manufactures products such as PV inverters, power optimizers and battery systems,' he says. 'We also advise and support installers and EPCs on complex projects, such as the Oudtburgh project. Using SolarEdge's Designer software tool, our engineers created a sophisticated string design for this site.'

Layout of the roof surface

Van der Vlist: "The number of PV panels and inverters in the project may not be extraordinary, but the application certainly is. Especially the layout of the roof surface and the engineering work involved is not ordinary. Generation Green and SolarEdge really worked together to achieve an optimal and aesthetically pleasing installation here.

First of all, the roof surface of Oudtburgh is not standard because the site consists of several buildings. And in addition, the roofs of those individual buildings are shaped like diamonds with six and sometimes seven facets/surfaces. Such a plane then has the shape of a triangle, parallelogram or trapezium. That means puzzling to properly distribute the PV panels. Based on supplied drawings, SolarEdge made a 3D layout of the building (or rather, the buildings) and configured it in consultation with Generation Green.

Optimizing yield

The technology that provides efficiency is central to SolarEdge inverters. Humfrey Disco said, "With a string inverter, the panel with the lowest yield leads the yield of the other panels in the entire string. We have placed so-called mpp trackers (maximum power point) in our SolarEdge Power Optimizers. This maximizes the yield of each individual PV panel, independent of orientation and inclination. Via the SolarEdge Monitoring platform, we bring the entire system into view 24/7 in real time. Any issues with the system are immediately detected and communicated to the system operator, without the need for on-site measurements first.'

Constantly shifting

The logistical aspect of the project was also complicated, in part because the site consists of multiple buildings. Van der Vlist explains, "There were various safety procedures and inspections, and multiple construction sites were set up on the grounds of the residential care facility. We made every effort to avoid any inconvenience to the residents. For example, we placed edge protection and lifting equipment per sub-building (unit), and the panels were installed unit by unit so that the work was limited to one spot. Thus, we moved up one building at a time. The difficulty was mainly that we could not limit access for the residents.'

Zero-export clause

A so-called zero-export clause applies to this project. Humfrey Disco explains: "Due to congestion problems, in more and more places in our country it is no longer possible to feed energy back into the grid. So too in Bergen. Therefore, we installed an energy meter on the main connection and set the export limitation to zero. The total of four SolarEdge PV inverters thus produce energy exclusively for our own consumption at the site. On the Monitoring Portal you can see in real time what is happening. You can also look back, of course.' Disco picks up the data from a random day in September. 'Here I see that 946 kilowatt hours were generated from the PV system. That was completely used up and the remaining came from the grid.'

Detecting arc flash threats

'We chose to install one SolarEdge Power Optimizer per two panels,' Disco says. 'The Power Optimizers are equipped with Sense Connect which allows abnormal temperatures at the input and output connections to be detected. As a result, arcs can be proactively prevented. Arcs can result from poor installation, cabling crimping, faulty connectors, incompatible connectors or improperly connected MC4 connectors. Such failures can cause fires, posing a real danger to a PV system and the properties on which they are installed. Anything for safety, and especially in such a healthcare environment.

Why wasn't terracotta-colored pv panels chosen? Yes, that could have been done here. But the thing is, most installers are pretty brand loyal. On top of that, we know that colored solar panels are somewhat less efficient anyway. Full black glass was chosen because it looks nice and because the yield is high; and after all, that's what it's all about.'

The numbers

The installation consists of 756 Trina Solar 435 Wp full-black glass panels and 124 Longi Solar 510 Wp panels and four SolarEdge inverters. In addition, SolarEdge Power Optimizers were used, one for every two panels. That results in 387 pieces of the SolarEdge S1000 Power Optimizer and 64 pieces of SolarEdge S1200 Power Optimizer.
The annual calculated power production is over 350 MWh.