Mohammad Eskandari - PV plant (stand-alone)

Stand-alone PV plant design

In this project we designed a Photo Voltaic Plant for a typical house in Milan, Italy.

First, we defined the global project framework such as: Location and main characteristics of the system (Coordinates, Nr. Modules, Tilt, Azimuth, PV Peak Power, yearly PV energy prod.,Tmax/min).

Second, we calculated Electrical Loads (user’s yearly consumption, daily peaks, electrical devices list and scenarios) for having best estimation for the size of plant.

Third, By using PVsyst software we simulate the shading on our plant in different seasons and specific days of the year.

Voltage matching

Then we chose the Inverter and charge controller according to our design. For this step the number of string modules is chosen in order to grant that the operating voltage range of the PV field falls within the voltage range of the MPP tracker, placed within the charge controller.

Our PV field results in 18 parallel-connected strings made of 3 series-connected modules each. In addition, The choice of the battery and sizing of it was made by taking into account the constraints for coupling with the other system components: charge controller and inverter. Finally, we worked on designing of Cable sizing and Strings layout which was Based on the results from the shading simulations, from which it is favorable to divide the plant in three different MPP areas, and from the modules connections required for the voltage matching of components, the following string layout has been adopted. Each line represents a series connection, each color refers to a specific charge controller.

The global electric scheme is reported below, where for each wire section information about current, voltage, length and cross area are provided.

A simulation of the system at operation conditions has been performed both for one week around the 21^st December and one week around the 21^st June. These simulations aim at ensuring that:

The SOC of the battery pack never falls below 20% so as to grant an efficient operation and long-lasting lifespan of the plant (critical especially during winter);
The battery pack is able to absorb and deliver power peaks that may occur during plant operation (critical especially during summer, when the plant witnesses the highest power production as well as the highest power consumption).
The power flowing through the stack during charge and discharge was below the maximum permitted value

The results of the winter simulation:

Economic analysis

In this part of the project the economic impact of the PV installation has been evaluated.

It is important to highlight how, since the plant is off grid, during the years the cost of the plant is recovered considering the avoided cost of electricity that is now produced by panels.

The economic analysis is based on an NPV evaluation over 25 years, which is assumed to be the lifetime of the plant, including all the cost for the plant and an annual revenue to take into account the avoided cost of electricity.

The economic analysis yields the following results, differentiating the scenarios with and without incentives:

PS:

All The results and analysis extracted and done by PVsyst & Excel.
More information are available upon request
click HERE for downloading the report