• UBIK Solutions

From asphalt to PV panels – new today

When you hear about solar energy generation, the first thing that probably comes to your mind is a set of dark blue rectangular grids of smaller squares connected that form a PV panel. And this is correct. If you were asked where the PV panels are used, most probably you will answer – rooftops. And this is a correct answer. But not only. Could you imagine the roadway producing energy? Actually, it is absolutely possible and is already implemented in Tallinn – Solar Road project and UBIK proudly takes part in this innovation act.

The boom of renewable energy production has triggered the installation of PV panels in rooftops, walls and dedicated solar farms. The governmental subsidies have enabled the installation of many solar farms in such extent, that they may put into the risk the usage of valuable agricultural lands, which must be protected and excluded from possible construction locations. It seems that we are running out of the potential places to build the solar power plants. That only seems so...

World is covered with man-made paved roadways and several companies across the globe have developed a solution that allows to harvest energy from Sun that hits the road surface. Main component of solar roadway is a durable block of glass or plastic that incorporates the PV element. These blocks are used to construct the upper layer of the road or at least part of it. The wires placed under the pavement connect the PV elements in series and parallel to form the PV batteries. Power electronic converters are used to direct the harvested energy to the electrical power grid, store it to the batteries or use it locally in road infrastructure like LED lamps, sensors, cameras and signaling equipment.

Now let’s switch to the Solar Road project implemented in Estonia, led by e-Pavement, in close cooperation with Ubik Solutions, Tallinn City, and TalTech. Estonian company e-Pavement has developed a solution for Nordic climate conditions, where PV elements are encapsulated inside the durable block, cast of polymer-glass compound.

Working principle of solar road

This compound is 5 times more durable when compared to the asphalt that covers our roads and it does not have slippery properties even when is wet (slippery coefficient 1). E-Pavement solar blocks can also be deployed to light the dark roadways or draw attention in dangerous passageways as most of them have also white, red and green LEDs integrated. The following image present real installations of these devices across Tallinn. Each PV element produces maximum 4.5 W power at 0.5 V and 9 A. To produce up to 270 W at 30 V, about 60 to 75 elements need to be connected in series. The power of installed single LED e-brick is 2.6 W.

Mektory crosswalk installation - Solar Road - the first installation of the project

To use the solar energy generated by PV panels, we also need the solar roadway dedicated power electronic converters. The most challenging is that compared to ordinary rooftop PV panels, the solar roadways have other type of issues. One of the biggest challenges is a frequent shading condition of these PV panels, provoked by vehicles, pedestrians, leaves, snow, sand etc. To maximize the energy harvest in such difficult conditions, there is a need for a maximum power point tracking (MPPT) algorithm and a wide range of input voltage and current. Since the PV panels are installed on a wet ground which may experience frequent wire isolation faults, it is crucial to have an isolated converter topology to ensure the safe operation of the system.

At UBIK we have developed a microinverter Optiverter S350 that can satisfy all the above-mentioned requirements without sacrificing its versatility, robustness and reliability. This device has input voltage range of 8 to 60 V DC and 1.3 A, 50 Hz, 230 V AC output voltage. Solar road pavement blocks are series connected into solar batteries that can deliver 40 to 60 V. Each Optiverter is dedicated to one battery that is connected to the 230 V AC power grid. First installations with UBIK inverters have been constructed in Tallinn Mustamäe and Pirita districts near Taltech MEKTORY and Tehnopol buildings.

Just think about the advantages this type of projects bring. The road is illuminated according to the pedestrian signals. When you can cross a road, it is illuminated with green light. It provides a pedestrian with additional awareness and creates safer environment on the roads. In addition to that, when you come back from work by your bicycle, the solar road will show you a way. And the most fascinating is that this energy is 100% renewable. Step by step UBIK is helping to build the greener future where energy is no luxury of few wealthy people but rather a public commodity available for all of us.

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