Methods and tools to maximize energy production in PV systems

PhD Poster Day 2015

Alessandro Ciocia, ID 29797, 2nd year of the PhD Official Tutor: Filippo Spertino

Methods and tools to maximize energy

production in PV systems

Attended classes

Characterization and planning of small-scale multigeneration

systems 5

Electrical load management, forecasting and control 5 Generatori e impianti fotovoltaici 5 Metodi di ottimizzazione per problemi ingegneristici 6 Programmazione in labview: parte 1 e parte 2 8 Sistemi elettronici di potenza per la generazione distribuita dell'e 4 Sviluppo e gestione di sistemi di acquisizione dati 5 Valutazione di impatto ambientale di campi magnetici ed elettrici a 4

16th European PhD School: power electronics, electrical machines, energy control and power systems - 2015 Gaeta, Italy

2015 IEEE ITALY SECTION SCHOOL ON FUTURE ENERGY SYSTEMS

Research context and motivation

1. Analysis of the sources of losses in photovoltaics generators (e.g., I-V mismatch in the PV array, partial shadings, mechanical defects,

underperforming inverters)

2. Use of capacitive loads to test the electrical parameters of PV modules and find MPP in working conditions

3. Analysis of electricity consumption profiles and correct sizing of hybrid PV-wind (HPVW) power systems and storage aimed at

Addressed research questions/problems

1. Recently, high feed-in tariffs and low PV module prices have permitted huge amounts of installed power plants. Sometimes, rapid design and installation have generated poor performance in grid-connected PV systems.

• What are the sources of losses?

• How can you recognize and quantify them?

Addressed research questions/problems

2. Directive 27/2012/CE requires that the European Union Countries

implement actions to improve energy efficiency of public administration buildings. By 2019, new and restored public buildings must have a very low energy demand, mainly produced by renewable sources (NZEB).

• How can we identify, within a large database (real estate), the office buildings which present a good/bad electricity performance, using only energy consumption bills?

• What are the sizing criteria of renewable systems (if possible, a

portfolio of different renewable source) and storage for different kinds of users?

• What are the benefits (for the user and for the distribution grid

operator) of a renewable system and storage designed to maximize self-consumption?

Addressed research questions/problems

3. The simplest and cheapest way to trace the I(V) characteristic of a high power PV generator of whatever size is obtained by charging a

capacitor.

• What are the characteristics of a capacitive load in order to achieve good testing on PV arrays of whatever size?

• What are the design criteria?

• Can we use the I-V scan to improve MPPT systems?

• Can we use the 5 parameters model to better understand the

behavior of the PV generator in shading conditions (using data from measurement of the I(V) characteristic)?

Adopted

methodologies

Defects in PV generators:

The study deals with the definition of a test procedures specifically conceived to highlight the degradation of PhotoVoltaic (PV) modules and identify the mechanisms that are mainly

responsible for their degradation.

Mechanical and thermal stress

 Damp-heat tests, i.e.tests at a high constant humidity and variable temperature that are conceived to accelerate the water adsorption and hence decrease the electrical insulation. Thermal cycles are in the range 20—70 °C

 Mechanical stress: cycles of static loads or dynamic loads. The latter condition has been obtained by mounting the sample on the vibrating table of an electrodynamic shaker (vibration cycles in the frequency range of 5 Hz to 150 Hz.

Test techniques

 The measurement of the I -V curve is a valid tool to continuously monitor the operation of an array of PV modules. Among the available methods, the capacitive-load based technique has been adopted, simultaneously detecting voltage, current, irradiance and temperature.

 EL analysis is able to detect different types of defects that may occur during each phase of the life of PV modules (i.e. production stage, transport, installation). Several defects can be highlighted by means of EL, such as: micro cracks, broken cells, impurities, chain pattern and Potential Induced Degradation (PID).

Novel contributions: Defects in PV generators

Pre stress Post stress

EL images of a p-Si PV module with semi-rigid frame before and after

mechanical stress

New cracks and isolated parts

Adopted

methodologies & Novel contribution

Electricity consumption analysis and design of hybrid PV-Wind (HPVW) systems with storage to increase self-consumption

The HPVW system is sized :

• simulating minute by minute PV and wind turbine production in one year (considering the various sources of loss) starting from real data

• simulating storage (Li-ion) using an energetic model

• considering the converter installation and simulating losses (starting from real data of commercial converters)

To find the cost-optimal solution and other cost-effective solutions in order to increase self-consumption and reduce power injection into the grid

AC Production

Load

Wind production

PV production

Adopted

methodologies & Novel contribution

Electricity consumption analysis and design of HPVW systems with storage vs. office loads

The cost-optimal solution does not include storage

AC Production Load PV production Wind production PV plant 3600 kW Wind turbines 1700 kW(2X850) Batteries 0 kWh

Annual load 4.6 GWh/year

Max 2300 kW

Adopted

methodologies & Novel contribution

Installed battery capacity (MWh)

NPV

Absorption from the grid

Grid injection

Self-comsumption

Energy flows and NPV with different storage capacities (vary from optimal solution).

Other cost-effective solutions: HPVW with storage vs. office loads

Published journal papers

• F. Spertino, A. Ciocia, P. Di Leo, R. Tommasini, I. Berardone, M. Corrado, A. Infuso, M. Paggi, A power and energy procedure in operating photovoltaic systems to quantify the losses according to the causes, Solar Energy, Volume 118, August 2015, Pages 313-326

• F. Spertino, J. Ahmad, A. Ciocia, P. Di Leo, A. Murtaza, M. Chiaberge, Capacitor charging method for I–V curve tracer and MPPT in photovoltaic systems, Solar Energy, Volume 119, September 2015, Pages 461-473

Published conference papers

• Spertino, F.; Ciocia, A.; Corona, F.; Di Leo, P.; Papandrea, F., "An

experimental procedure to check the performance degradation on-site in grid-connected photovoltaic systems," in Photovoltaic Specialist Conference

(PVSC), 2014 IEEE 40th , vol., no., pp.2600-2604, 8-13 June 2014

• Spertino, F.; Chicco, G.; Ciocia, A.; Corgnati, S.; Di Leo, P.; Raimondo, D., "Electricity consumption assessment and PV system integration in grid-connected office buildings," in Environment and Electrical Engineering

(EEEIC), 2015 IEEE 15th International Conference on , vol., no.,

pp.255-260, 10-13 June 2015

• Ahmad, J.; Ciocia, A.; Spertino, F., "A Maximum Power Point Tracker of photovoltaic arrays for partial shading conditions," in Industrial Engineering

and Operations Management (IEOM), 2015 International Conference on ,

Published conference papers

• Spertino, F.; Ahmad, J.; Ciocia, A.; Di Leo, P., "A technique for tracking the global maximum power point of photovoltaic arrays under partial shading conditions," in Power Electronics for Distributed Generation Systems

(PEDG), 2015 IEEE 6th International Symposium on , vol., no., pp.1-5,

22-25 June 2015

• Carullo A. , Vallan A., Ciocia A., Spertino F.; " Degradation tests and

characterization procedures of photovoltaic modules exposed to outdoor conditions" , 2015, at XXI IMEKO world congress, Prague

• F. Spertino, J. Ahmad, G. Chicco, A. Ciocia, P. Di Leo, "Matching between Electric Generation and Load: Hybrid PV-Wind System and Tertiary-Sector User – Forthcoming.

Future work

• Advanced analysis of the losses in PV generators

• Analysis of total electricity consumption of utilities in large real estates, subdivision into different loads (disaggregation) and identification of underperforming buildings (with clustering methods).

• Advanced study of the behavior of a PV generator in shading conditions

• Correct sizing of hybrid PV-wind (HPVW) power systems and storage

 Integration of a better battery model to evaluate the SOC and also State of Health (SOH)

 The integration of multiple locations with generation systems and storage

 The integration of other types of renewable sources

 The use of a model to predict load and generation and better manage storage

 Use of an optimization tool to find optimal solution in bigger problems