Design the power of a PV system for a single family building in Älvkarleby with the simulation program Winsun PV.
Winsun for PV-Simulations
Input to the simulations in tab “Input and result”
Inputs to the simulations are written in the yellow cells:
Cell C6 Tilt of the modules in degrees
Cell C7 Direction of the modules (east=-90, south=0, west=+90)
Cell C8 Reflectance or albedo of the ground (0,0-0,2)
Cell C9 Horizontal shading in degrees. If the solar altitude is lower than C9, than only diffuse irradiation from the sky will reach the module.
Cell C12 Nominal power of the modules in kW
Cell C13 Area of the modules=Power/Efficiency ~P/0,17
Cell C16 Losses in inverter and wires (0,90-0,95)
Annual results of simulation in tab “Input and result.”
Cell C19 Total AC output from the inverter in kWh/year
Cell C20 Specific output in kWh/(kWp)
Cell C21 Performance Ratio
Cell C22 Efficiency of the modules
Hourly results of simulation in tab “Hourly data”
Column B Irradiation on modules (kWh/h)
Column C AC production from PV-system in (kWh/h).
Column D Hourly demand of the building in (kWh/h)
Column E Net hourly demand=D-C in (kWh/h)
Column F Electricity from the grid in (kWh/h)
Column G Electricity from the PV-system to the grid in (kWh/h)
Column H Saved electricity by the solar cells, i.e. electricity from the solar cells which is used directly in the building.
The annual results are given in raw 8766.
The hourly electric load in kWh/h for the building is in the tab “Hourly data”, column D.
January d6-d749
February d750-d1421
March d1422-d2165
April d2166-d2885
May d2886-d3629
June d3630-d4349
July d4350-d5093
August d5094-d5837
September d5838-d6557
October d6558-d7301
November d7302-d8021
December d8022-d8765
The annual demand of facility electricity of the building is 11267 kWh/year as given by cells D2 and D8766.
Daily PV-production and electrical load.
Daily PV-production and electrical load are given in the tabs “Hourly data”, columns J-P. These are calculated by daily summing of columns C-H. This information can be used to estimate the benefits of daily solar storage.
Climate File
The used climate file is in the tab “Climate Files” columns D-F. It represents Älvkarleby-2017 and comes from the STRÅNG-system at the Swedish Metrological Institute.
Simulations
A PV system in Sweden is connected on the inside of the electric meters. This means that the PV-system will both save electricity and export electricity to the grid.
When the building is using more electricity than the PV-system generates, then the PV-system saves electricity.
When the building is using less electricity than the PV-system generates, then no electricity is bought from the grid and the PV-system will export the over production to the grid.
A saved kWh has a value of 1,4 SEK/kWh.
An exported kWh has a value of 0,5 SEK/kWh.
Example 2,6kWp-system
The tab “Hourly data” gives the annual results in the cells D2 and F2-H2.
It shows the results of simulations of a 2,6 kWp-system:
| Demand | 11267 kWh/year (measured data) |
| Total PV-production | 2043 kWh/year |
| Electricity from the grid | 9855 kWh/year |
| Exported PV-electricity | 631 kWh/year |
| Saved PV-electricity | 1412 kWh/year |
Theory and Calculation
The equations which are used in the program are given in the tab “Theory&Calculations”.
Assignment
Simulate the annual output for a system with module tilts of 27° and direction 36°. Systems with the power between 1 and 15 kWp should be simulated.
- Make a figure, which shows the daily use of electricity over the year.
- Present the results in a figure with month on the x-axis and the electric load and the monthly solar electric production on the y-axis for systems of different power.
- Present the results in a figure with the PV-power on the x-axis and the generated annual energy(C2), bought annual energy(F2), saved energy(H2) and exported energy(G2) on the y axis for systems of different power.
The following questions should be answered:
- Which PV-power will give an annual production which is equal to the annual use of electricity (11 267 kWh)?
- For which PV-power is the PV-production in July equal to the use of electricity in July?
- For which PV-power is exported electricity equal to electricity bought from the grid?
- Which size of the system do you suggest? Discuss why you choose that system size.
- For the suggested system, calculate the own consumption of electricity with both hourly values and daily values, discuss the results.
- For the suggested PV system, find a suitable PV-module and design a system with a suitable inverter. Draw a drawing/sketch of the system with the number of modules in each string (if more than one) and calculate voltage as described in lecture 14. Find fact sheets online, there could be modules from Trina Solar or Jinko Solar but there are many to choose from. Inverter manufacturers are for example Fronius and SMA but there are many other as well.
Daily Storage
Batteries can be installed in the system for storage of electricity from day to night. Daily storage can be modelled by using the daily integrated values in the columns J-P. Use these data for presenting the performance of a system with daily storage.
- Present the results in a figure with the PV-power on the x-axis and the generated annual energy (K2), bought annual energy (N2), saved energy (P2) and exported energy (O2) on the y axis for systems of different power and batteries for daily storage.
- Which size of the system with daily storage do you suggest?
- How many kWh should the batteries be able to store? Investigate how many kWh the building use during the time 18:00-06:00.
Report.
Write a short report, which shows that you have understood the results of the simulations and which answers the above questions. The report should include the figures described above. The figures should have a figure text.
It should be dimensions on the axis.
Don´t use too many decimals!
