Along with the Solaredge inverters, a PV installation comprising 824 panels was installed on the roof, allowing the maximum yield to be utilised. As a whole, the installation is able to supply approximately 220 MWh of power a year, which is approximately two thirds of the company’s overall energy consumption, which means Nijman/Zeetank will be able to reduce CO2 emissions at
the Spijkenisse site by approximately 100,000 kg.
A parallel system was chosen where, using an optimiser, the
panels are connected to the inverter in pairs. A major benefit of this configuration over the string system (up to 30 panels connected to one inverter) is that the yield remains high when
the panels are in the shade or if they are dirty. Using a simple
tool on the computer or smartphone, this enables the PV installation to be monitored at panel level, plus any failures can easily be identified, using a virtual layout of the roof in the monitoring system. (see illustration 1).
The 824 panels are mounted on an ultra-light mounting system. The north-south configuration prevents peak power outputs that are too high. This configuration means that the peak power output is a little lower, but during the day more solar power is generated and therefore reinforcement of the main connection wasn’t necessary. Furthermore, the installation is fitted with a dynamic power control. This increases the capacity of the entire installation by first measuring the installation’s own consumption and then adding this in real-time to the capacity of the connection.
This smart system therefore ensures that electricity generation can continue unhampered when consumption is satisfied.
(see illustration 2).
A PV installation often works at a high voltage and a voltage of
500 V between the panels and the inverters is perfectly normal. The combination of optimisers and inverters ensures that, in the event of a power failure or if the current is interrupted, the
voltage is reduced to a harmless level of around 20 V.
Prior to the system being installed, the strength of the roof was properly calculated, and to be able to guarantee good drainage after installation, the run-off of the roof was increased by 15 mm. The steel beams were pushed up and bolstered and because of
the innovative technology, no changes were needed to the structure of the roof itself. The total installation results in an additional roof load of on average 15 to 20 kg per m2 extra.
This additional roof load has been compensated for by enlarging the existing drain holes in the roof and the bitumen roof covering was also replaced. This has resulted in a ‘green roof’ that can provide Nijman/Zeetank with renewable energy, hassle-free, for the next 25 years.
Not only is Corporate Social Responsibility a hot topic in the sector, but as a logistics service provider which uses vehicles that produce CO2 emissions, Nijman/Zeetank believes it is also its moral duty to operate as sustainably as possible. For years, on-site energy consumption has been a major expense for the Company.
The workplace, office, container crane and the industrial heating system for tank containers in Spijkenisse all use electricity.
In recent years, the company has invested significantly in systems that use electricity more efficiently and over the past ten years this has resulted in a 25 percent decrease in total energy consumption even though the Company has undergone an expansion and seen further growth in its activities. A new roof-mounted solar array will now reduce the use of fossil energy and the production of CO2 emissions further still.
For a long time, we have been playing with the idea of using the 1,750 m2 roof of the warehouse in Spijkenisse to generate renewable energy; however, everyone has been trying to get in on the act of the turbulent solar panel market, and this made us tread carefully. A PV installation (photo-voltaic, or an installation that converts solar power into electricity) is a considerable investment, with a long payback time and for that reason, reliable suppliers who are able to offer good guarantees are also important.
The Sustainable Energy Foundation (Stichting Duurzame Energie) helps businesses in the Netherlands to reduce this payback time; with a subsidy in place, for a 15-year period, a tariff is paid for each kWh generated. This is, however, subject to the condition
that once the subsidy has been awarded, the installation must be completed within a three-year period.
We found a supplier who, based on technology and innovation, is perfectly in keeping with Nijman/Zeetank’s own business philosophy; this supplier offers a German panel, developed and manufactured entirely in-house. During meetings, a good relationship was formed with the supplier and the manufacturer, which resulted in us becoming the first company to take delivery of the latest Bisun glass panel. By using the latest glass technologies, this solar panel also has a very long life expectancy, high mechanical durability and low degradation rate. The installation operates on daylight, meaning solar power is even produced when it is raining or foggy. This is because the solar panel backsheet is made from glass instead of synthetic foil, which does perhaps increase the cost of the panel, but the glass is less vulnerable than plastic to the effects of UV light. This construction guarantees a low degradation rate of the panel.