PV and Storage Optimization Tool – Manual



PV and Storage Optimization Tool has been built in the framework of “Promotion of higher penetration of Distributed PV through storage for all - StoRES” project. The objective of StoRES is to boost PV self-consumption in the MED region through an optimal residential storage solution. The approach is to test coupled solutions for the consumer in different pilot sites taking into account local parameters for optimization and using efficiency measures. StoRES is expected to change the current situation concerning grid reliability with higher Renewable Energy Sources deployment in islands/rural areas, giving a cost-effective option to the public on more affordable and sustainable energy supply.

The tool aims at calculating the optimal size of a hybrid PV+storage system in terms of net present value of the investment. The tool requires as inputs: electrical consumption, solar irradiation, PV and battery size, and electricity costs. A financial analysis is undertaken for a period of 20 years, taking into consideration technical and financial parameters and various options of energy policies. The tool can be used by both professionals and non-professionals users.

This document is a short manual, providing the user with simple instructions. The procedure that should be followed to get the desired results is divided into 8 separate steps:

·         Step 1: PV System Data

·         Step 2: Consumption Data

·         Step 3: Electricity Costs

·         Step 4: Storage System

·         Step 5: Policy

·         Step 6: Financial

·         Step 7: Validate Inputs

·         Step 8: Getting the results

These steps are further analyzed in the remaining document.

 

Step 1: PV System Data

 

i.            The “PV production profile” is essential for the tool calculations. The user should select one of the following two options:

a)       If PV power measurements of a specific installation are available, the user can import these data in a .csv file and upload it by clicking “Upload”. The data should be entered using the sample template that can be downloaded from the corresponding button. Next, user should enter the PV capacity (in kWp) of the measured PV installation.

b)      If no PV power measurements are available, the user can indicate the coordinates of the installation position and the orientation of the panels (slope and azimuth). The tool then communicates with the PVGIS platform[1] of the JRC and obtains the necessary climatic data for the specific location in order to estimate the PV power output. The calculation procedure is described in detail in a relevant publication[2].


The next image is an overview of the .csv template file. Power should be imported in kW, considering a 15-min time interval.

 

       ii.            In the same Tab, the “PV System characteristics” – degradation and inverter efficiency have to be introduced.

 

     iii.            The last option of this step refers to the “Type of Analysis”. The option to choose between a single PV size and various PV sizes is given and the user is able to switch accordingly to his proper installation.


[1] http://re.jrc.ec.europa.eu/PVGIS5-release.html (Assessed March 2019)

[2] G. C. Christoforidis, I. P. Panapakidis, T. A. Papadopoulos, G. K. Papagiannis, I. Koumparou, M. Hadjipanayi and G. E. Georghiou, “A Model for the Assessment of Different Net-Metering Policies”, Energies, 2016, 9(4), 262; doi:10.3390/en9040262.


Step 2: Consumption Data

The consumption of the installation should be inserted here. In this case, the user can either use a predefined country-specific consumption profile by introducing his monthly or yearly consumption, or upload a customized profile of the installation.

i.            Monthly Consumption Data: Select the country of the installation under study and insert the energy consumption of each month over a year, in kWh.

 

ii.            Yearly Consumption Data: Select the country of the installation under study and insert the total energy consumption over a year, in kWh.

 

iii.            Customized Profiles: The user has the option to upload own consumption by means of a .csv file using the provided template. The template can be downloaded by clicking the corresponding button.

The next image is an overview of the .csv template file. Power should be imported in kW, considering a 15-min time interval. Consumption should be inserted in the specified columns per month, taking into consideration a classification between working and non-working days.


Step 3: Electricity Costs

This tab consists of two options describing the electricity costs of the installation under study.

User can choose between either a “flat pricing” scheme, i.e. constant electricity charges throughout the period of a day, or a “dynamic pricing” scheme, where more than one time zones are valid.

In the dynamic pricing scheme, user should specify if two or three charge zones exist, by checking accordingly the “Zone C” option. The starting hour of each zone should be declared in an ascending order, beginning from Zone A. The ending hour is automatically filled in. Electricity costs should be inserted accordingly. It should be noticed that a dynamic pricing scheme cannot be selected when a “Partial net-metering” policy is selected in the “Policy” tab.

 

All values should be entered before VAT. Specifically,

·         “Production cost” corresponds to the charges per kWh for the generation of electrical energy. It includes supply costs as well.

·         “Network cost” corresponds to the costs per kWh that are charged to the prosumer for the use of distribution network and transmission system.

·         “Taxes” include all other charges that may be applicable.

·         “Fixed cost” refers to the fixed annual charges.

·         “VAT” is the VAT that applies to the total electricity cost (sum of the above).

 

Step 4: Storage System

The characteristics of the Battery Energy Storage System (BESS) are defined in this tab. The user is able to perform an analysis for different BESS sizes.

The expected “overall number of charge/discharge cycles” should be inserted, as declared by the manufacturer of the BESS. A number of 8000 cycles could be used as a typical value for Li-Ion batteries.

User should also define “maximum charge/discharge rate” of the BESS, as a percentage (%) of the nominal battery capacity. For example, if 50% is selected here, a 10 kWh BESS will have a maximum rate of 5 kW.

Finally, user should define the BESS size range to be analyzed by the tool.

Step 5: Policy

The user is able to choose between 3 policies from the drop-down menu “Select Policy”:

         i.            The first option refers to the “Pure self-consumption” policy, where PV excess energy exported to the grid is not compensated at all.

       ii.            The second option refers to the “Self-consumption” policy, where PV excess energy exported to the grid is compensated at the price specified in the corresponding box further down.

     iii.            The third option is available only under a “Flat Pricing” scheme (this can be chosen in the “Electricity Costs” tab). Specifically, it refers to a “partial net-metering” policy, where prosumer is charged on the net consumed energy by the production cost price, at the end of each billing period. If there is a surplus of produced energy (net consumed energy is zero in this case) over a billing period, this amount of energy is transferred - in the form of renewable energy credits - to the next billing period. At the end of each year, any renewable energy credits are erased. Prosumer is charged on the imported energy by the network costs and taxes declared in the “Electricity costs” tab.

Furthermore, the user can define any added cost or added income that may apply to the prosumers for operating a PV or/and storage system.

Step 6: Financial

User should define the cost of purchasing the equipment, the Operation and Maintenance (O & M) costs of the hybrid PV and storage system, the subsidy as a percentage of the overall system cost, the discount rate, the inflation rate and the electricity inflation rate as shown below.

“PV and inverter cost” includes the cost of PV panels, the hybrid inverter, engineering, administrative and balance of systems costs (per kWp installed), whereas “BESS cost” refers to the battery energy storage system cost (per kWh), and includes only the cost of the battery module.

  Step 7: Validate Inputs

Once all the data have been inserted, user has to validate them by clicking on “Validate Inputs” button. A pop-up window confirms the validity of the inputs. The message indicates where the problem exists, if so, and after solving it, the user has to revalidate the inputs. A soon as the emerged message is the following, the user can close the window.

Step 8: Getting the results

Once the validation of the inputs is successful and the pop-up window is closed by the user, the tab “Results” is activated automatically. No results are depicted yet. The user has to click on “Calculate” button so that the tool starts the analysis.

When the analysis is finished, the results will be visualized on this screen. Analysis has a duration of several seconds to 2 minutes, respecting to the user specified options (PV and BESS size range for analysis).

To export the input data and the results in form of a .pdf file, user can click on the proper buttons that appear on the right-top of the page.