Introduction
During my master in Engineering of Solar Energy at University of Évora, I had the opportunity to do my Erasmus at Utrecht University, in Netherlands and develop my research project that the goal was to estimate the yearly yield potential (through the use of PVsyst software) using solar panels inside the De Uithof campus located at Utrecht, Netherlands, which contains the De Uithof campus, the campus area of Utrecht University, the vocational University Hogeschool Utrecht and the academic hospital University Medical Center Utrecht (UMCU). Solar parking lots, building attached photovoltaic (for the roofs and facades) and charging electric vehicles (EV) are the chosen uses of solar energy for the present project.
State-of-the-art
The three technologies used for this project are just a part of the several ways to use solar energy, and are solar parking (Section 2.1), building attached photovoltaic (Section 2.2) and charging electric vehicles (Section 2.3)
Solar parking lot
The solar parking lot is one of the ways to use solar panels integrated into the structures of the parking lots. This solution is good to charge electric bikes, motors and cars, and also allows them to charge electronic devices (like computers, cell phones, power banks and so on). Another advantage is that with the use of solar parking lot, protect the cars from meteorological conditions like snow, sun, rain, wind and hail. Basically we have two types of structures, can be rigid (traditional solution, lowest price and fast execution) or flexible (lightweight roof, fewer pillars and steel structure), for this presently project, the rigid system was chosen.
Building attached photovoltaic (BAPV)
As the buildings are already in use, it is cheap to simply attach the solar panels on the roofs and facades, rather than change the structures of the buildings to integrate the solar panels (BIPV), this technology can split into three types: Tile-on roof system (used at tile roofs like hollow, flat roof, standard, double slot, roman, plain, scale, bitumen, slate and spanish tiles, the PV modules are fixed on the roof using hooks and mounted using rails and clamps), metal sheet roofs system (used in metal sheet roof is considerate hardcore for roof system, but with matched clamp and rail is possible to fix the PV panels on the metal sheet roofs) and flat roof system (used in all kind of flat roofs according to the roof support capacity with the weight of the solar plant and waterproof requirements).
EV charging
To charge the electric vehicle (EV) requires plugging into charger equipment that is connected on the electric grid, and the equipment calls electric vehicle supply equipment (EVSE) (Morrow, 2008). There are four models of charging that depend on the amount of power coming from the charger to the battery, furthermore, four connector types.
Method
The work method is divided into five parts:
- Firstly a 2D part that was done on ArcGIS software to create the shapefile with the buildings (using the maximum height) and solar parking, and calculating the total amount of incoming radiation for the entire year in Wh/m2 through the tool Area Solar Radiation.
- Secondly, the 3D works on AutoCAD, Autodesk FBX Converter and PVsyst to create the 3D plant and import the shapefile into the shading scene construction, to install the solar modules on the roofs, facades and solar parking lot that include the input data (module, inverter, design, shadings and losses).
- The third part is Carbon balance calculus that represents the amount of dioxide carbon emission that will be avoided.
- The fourth part is related with the type of charge that is the charging mode 3 (there are four ways to do it based on the IEC-61851-1 standard) combined with connector type 2 (there are four types of connectors based on IEC 62196-2 standard) that fully charge the Tesla Model 3 (which has a battery of 50 kWh) in around five hours (charging 11kW per hour), with this, estimate the number of cars that can be fully charged per day through a rough calculus.
- The firth part details the input data for the economic viability calculus considering the total cost of initial investment and operation/maintenance costs.
Figure 1 displays briefly the step by step that I used to get the results.
For the project, VC0 (Figure 2) and VC1 (Figure 3) (names provided on the software to the different projects) represent the simulation tests:
- VC0 – with the modules facing South – Azimuth of 0°, but some turned because of the facades or roofs of the buildings; 90° tilt for the facades and 34° tilt for the roofs and solar parking;
- VC1 – with the panels facing South + West-East direction – Azimuth of 90° and -90°, the larger number of modules with the West-East side orientation, but some stayed turned to the South, the Tilt angle is 90° for the facades and 34°for the roofs and solar parking.
Results
For the results, we can divide in: Solar potential (for the 2D and 3D part), EV charging that displays the estimative of how many cars can be fully charged per day and economic analysis.
Solar potential
The Solar potential part includes: 2D made on ArcGIS, 3D did on PVsyst and the Carbon balance calculus.
2D part
The output raster represents the global radiation or total amount of incoming solar insolation (direct + diffuse) calculated for each location of the input surface. The values subdivide into five levels that begin at 8,72 Wh/m2 until 1.044.596,06 Wh/m2.
3D part
After the 3D simulation on PVsyst, were able to estimate the yearly yield production, in MWh/year for each project (Table 1).
Table 2 displays how many solar panels were used for each project and focused on facades, solar parking and roofs.
Carbon balance calculus
The carbon balance calculus basically displays how much the system will avoid in terms of CO2 emission. VC0 saves 196.770,867 tons of CO2 and VC1 saves 242.114,490 tons of CO2.
EV Charging
Table 3 shows the Average number of charged cars per day for the entire project and for solar parking.
Economic analysis
Table 4 shows a positive value of NPV (for both ways of calculus), which results that the project is economically viable. TLCC is the total cost, representing the sum of installation costs (CAPEX) and operation (OPEX) of the solar power plant. The payback has a value of 7,69 years, lower than the lifetime that is 25 years. The LCOE has a value of 0,058 €/kWh when the solar plant is working.
Table 5 shows a positive value of NPV (for both ways of calculus), which results that the project is economically workable. TLCC is the total cost during installation (CAPEX) and operation (OPEX) of the solar power plant. The payback has a value of 7,03 years, lower than the lifetime that is 25 years. The LCOE has a value of 0,064 €/kWh when the solar plant is working.
Graphic 1 display the accumulated cash flow for both projects that starts at year 0 (for CAPEX) and from year 1 until 25 we have the OPEX, furthermore, at the year 13 we have the changing of the inverter, that is why we have the “same” value for year 12 and 13.
Conclusion
The De Uithof campus represents an enormous potential for producing energy as we can install the solar panels on the roofs (the major possibility), then followed by the facades, and then the solar parking lot. And we can see that during the autumn and winter the power production is lower because of the weather as we have more clouds, so more shading on the panels.
The technical results show that the production of VC0 and VC1, that is, respectively, 27.229 MWh/year and 35.285 MWh/year are satisfactory results taking into account the size of the solar plant, because it is possible to obtain good value of yearly average performance ratios for both projects, 0,775 and 0,757 (VC0 and VC1, respectively), as the numbers are near to the unitary value, meaning a very reliable performance of the entire system.
Looking at the number of charging station, due to the VC0 production, is possible to charge 473 EV/day in December (the lowest value) and 2.237 EV/day in May (the highest value). Even focusing on solar parking, the number is quite good, being 30 EV/day in December (lowest value) and 140 EV/day in May (the highest value). For the VC1, the numbers are greater since the VC1 production is higher. If the produced energy is used to charge electric bicycles, surely these numbers will be higher.
The economic analysis demonstrates that both projects are economically feasible because the NPV have positive values (€68 million and €83 million), the payback time (7,69 and 7,03 years) are acceptable for such an investment, being much lower than 25 years, the solar cells usual lifetime cycle, plus with the values of LCOE (0,058 €/kWh for VC0 and 0,064 €/kWh for VC1).
This project represents an environmental positive result since avoiding dioxide carbon emissions (196.770 tons for VC0 and 242.114 tons for VC1), avoiding also emissions of other GHG, currently associated with the production of energy with fossil fuels.
Bibliography
Oliveira, T. D. (2020). Facades and solar parking yield estimation at Utrecht University (Master’s thesis, Universidade de Évora). <http://dspace.uevora.pt/rdpc/handle/10174/26741>
