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New life for greenhouse of Sundial B.V.

From an interest in investing in renewable energy, Cor Poppe, owner of Zonnewijzer B.V., had the inventive idea of using a greenhouse as a carrier for some 20,000 solar panels. This could generate power for about 1,900 households. An interesting project, also according to ProfiNRG and Energie Expertisecentrum Flevoland (EEF). Together, these parties joined forces and after coordination with the Noordoostpolder municipality and pleasant cooperation with Flevoland province, the project was completed last month: the first solar panel greenhouse is a fact. 

An inventive investor

Whether it would be in solar panels or wind turbines, Cor Poppe was keen to invest in green energy at a young age. "Green energy is important and it's permanent, that's what I love about this investment," Cor Poppe says. "I myself am originally from Creil and I had made remote investments before, but I never liked it. That's why I wanted to make a sustainable investment in the neighbourhood. At that time, there was no policy for this from the municipality, so I had to come up with a plan myself first. A greenhouse has a large roof and after some research I found out that it is theoretically possible to install solar panels on such a roof. A favourable aspect of this is that a roof is permit-free. Of course, I checked this with the municipality, but they confirmed what I already thought myself: it is allowed."

EEF and ProfiNRG join forces

So, in theory, a solar panel roof could be realised, but as this has hardly ever been done before, a party that could do this in practice had yet to be found. For this, Cor Poppe contacted EEF. "We then selected a number of suitable parties, drew up the EPC request and had a site inspection carried out," says Willem Enklaar, director at EEF. "Because a greenhouse is basically not built to have PV systems on it, a smart solution had to be devised. ProfiNRG matched all the requirements best. Together with Cor, ProfiNRG came up with a construction that eventually had to make it possible to place the solar panels on the roof of the greenhouse.


One such existing installation method is to install panels over the existing glazing, which effectively builds two structures on top of each other. "This is far from ideal and relatively expensive, as the substructure is often not designed for the extra weight of the panels," says Cees van de Werken, director of ProfiNRG. "Another common practice is to replace the existing glass. You then mount the new frameless solar panels between the profiles of the greenhouse. The big disadvantage of this approach is that you often run into size problems.

The solution we developed and applied together with Cor for the greenhouse of Zonnewijzer BV is a construction consisting entirely of normal solar panels on the existing rods. Van de Werken: "This has the advantage that we were able to reuse as much of the existing construction as possible. We remove the glass, and apply a profile system to the rods, into which the panels can be slid. This makes for a solid construction. If you work with frameless panels, this is often very vulnerable." It is not only sturdiness that is important, the construction costs of this new construction system are also very favourable. Van der Werken: "Roughly speaking, you can say that the pricing is comparable to the cost of normal ground-mounted PV systems of similar size. We therefore expect this project to attract the interest of new parties."

Next, a financing plan had to be arranged for this construction. Here, too, EEF was able to help. Several financiers were approached by EEF. They then helped in the negotiations and finally one financier was selected.

Double-function solar greenhouse

In the most ideal situation, in addition to generating electricity, the greenhouse can also be used in its entirety as a greenhouse where crops can be grown. Should this prove only partially possible, there are plenty of opportunities left to use remaining space in the greenhouse in multiple useful ways. Cor Poppe: "In solar panel country, people are very much looking for a situation where a dual function can be created. A field arrangement with solar panels on agricultural land can't do anything else. In addition, society generally regards such a field arrangement as ugly. By placing the solar panels on the roof of a greenhouse, we hide them from the view of passers-by. The visibility of the panels on the greenhouse is zero while the cost of such a construction compared to a field arrangement is almost the same. In the coming period, we will investigate whether we can still grow crops in the greenhouse during the hot summer months. There is also the option of using part of the greenhouse as storage, should the greenhouse function (partially) not be possible after all.

In the end, everything was a profit. The greenhouse was ready to be demolished. The construction of the greenhouse was still spotless, but otherwise it was economically written off. The demolition had also created a lot of demolition waste. Now we can generate solar energy for the next 15 to 30 years and give the greenhouse a dual function. In addition, once the economic lifetime of the panels is over, the greenhouse can be converted back into a 'normal' greenhouse. This is actually the ultimate form of sustainability and I think we should be very proud of it. I am very happy that the municipality has agreed to this and I hope we can be an inspiration to others. Everyone looks for a certain double feature with sustainability projects. We have found one with this."

If Cor had wanted, he could have resold his project to various interested parties at home and abroad. Yet he chose to keep it close to home. "We have been approached several times to resell this project to (foreign) investors. We wanted to do this precisely in the polder and that is where we want to keep it. At Zonnewijzer B.V., we think along the lines of: for the polder, by the polder."

About Energy Expertise Centre Flevoland (EEF)

With the Energy Expertise Centre Flevoland (EEF), we help entrepreneurs, non-profit organisations and energy cooperatives in Flevoland to develop, finance and realise their sustainable energy and energy saving projects. Our goal? To accelerate energy transition in Flevoland and thereby strengthen the local economy.

More information: www.eef-flevoland.nl

About ProfiNRG

ProfiNRG is a builder and O&M party for large-scale solar energy installations from 250kWp upwards and supplier of total packages to installers from 100kwp upwards. For more than 10 years, ProfiNRG has been supplying sophisticated solar energy installations to their customers. They work directly on behalf of agricultural and wholesale companies, governments, construction and installation companies, or on behalf of developers.