Saturday, November 21, 2015

New Version of Renewables Alternativ Powersystems Simulation (RAPSim) Supports Your Own Model Implementations

We are proud to annouce a new release of our Renewables Alternativ Powersystems Simulation (RAPSim) software. The current version 0.92 is now available on the sourceforge page of RAPsim.

It has been some time since the RAPSim software had been presented at  the IEEE Innovative Smart Grid Technologies Asia and also announced in this blog.

Renewable Alternative Powersystems Simulation
Since then we improved the graphical user interface to allow a smooth interactoin between user and simulation system and improved the software structure to allow for an easy extension of the simulator with your own models. At the 12th Workshop on Intelligent Solutions in Embedded Systems we presented this feature in detail. The main steps are:
  1. Select the correct abstract class and define general attributes. A structure of abstract models is provided to handle all the interaction with the objects and the other simulation parts. The user has to name, describe the model and add an appropriate icon for the model. 
  2. Model parameters must be defined for being available in the GUI. The provided data type deals also with complex numbers. Dependent on the type of implemented model the user can define which variables are editable and visiable. This is also the place to set initial values. 
  3. Define the update procedure. This is the main part of the model implementation, meaning the mathematical part is done here. This includes also the possible allignment of data from an external source, like a file, with the simulation time. 
For details about model implementation please see the paper on this topic which was presented at the WISES 2015:

M. Pöchacker and W. Elmenreich. Model implementation for the extendable open source power system simulator RAPSim. In Proceedings of the 12th International Workshop on Intelligent Solutions in Embedded Systems (WISES'15), pages 103–108, Ancona, Italy, October 2015.

and the RAPSim introduction paper:

M. Pöchacker, T. Khatib, and W. Elmenreich. The microgrid simulation tool RAPSim: Description and case study. In Proceedings of the IEEE Innovative Smart Grid Technologies Asia (ISGT-ASIA'14), Kuala Lumpur, Malaysia, 2014. IEEE.

Sunday, November 15, 2015

Photovoltaics Energy Payback Time

Photovoltaic systems are great in producing clean energy without CO2 emissions. A question that remains however, is the amount of energy invested into production and transport of the materials, cells and panels. To answer this question, we had a look into the annual Photovoltaics Report of the Fraunhofer Society (German: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V.).

To give a short summary: The energy payback time for current modules is around one to two years. Considering a lifetime of 20 years, this means that photovoltaic systems are quite effective in providing clean energy. The energy payback time depends mainly on three parameters: (i) the  material usage for the system, (ii) the effiency of the cells and panel, and (iii) the irradiation striking onto the panel. Regarding the first aspect, the report shows that material usage for silicon cells went down by a factor of 2.5 over the last ten years due to increased
efficiencies and thinner wafers. Efficiency is improving slower, currently the best multicrystalline modules provide an efficiency of 18.5%, panels with monocrystalline cells a 22.9% and upcoming thin film technologies have a range between 10.9% and 17.5%.

The largest influence for the energy payback time currently is the place where you put your module: In regions with an annual irradiation of around 1000 kWh/m2 - this is basically the value for PV panels installed in Germany, they energy payback time is 2 years, while in sunny areas, the annual irradiation can be double or more, leading to an energy payback time of around 1 year.

Energy payback time for typical PV systems in different regions of Europe