PV Converter & Controller: How to improve the performance and

smartness of your solar system

Dr. Walter Marin, PhD Power Electronic

Protronic Group Strategic Business Partner

Foreword

Solar panels offer the opportunity to tap into a limitless energy source and contribute to national energy self-sufficiency. The solar inverter is a critical component of an entire solar energy system. It performs the conversion of the variable dc output of the PV cells into a clean sinusoidal 50-Hz or 60-Hz voltage source suitable for supplying the commercial electrical grid or local electrical network.

Impressive progress has been made to date improving the materials that convert solar energy to electrical power. Equally important, however, are the challenges of maximizing the efficiency and smartness of the overall system.

Walter Marin’s CV

Walter Marin, PhD Power Electronic, is an engineer with 25 years experience in researching, designing, manufacturing and marketing Power Inverter in range from 100 W to 20 kW. He participated in pioneering the high-frequency power inverter in welding application; as results of his valuable job a paper “Electronic Welder with high-frequency resonant inverter” appears in Industry Applications Society Annual Meeting, 1993, Conference Record of the 1993 IEEE where a new generation of electronics welders, incorporating soft-switched inverters driving high-frequency transformers, is presented.

Since then, he has been furthering his design and research in the European and US industry, manufacturing hundred of thousands power inverters light, reliable and flexible offering to the market products with good efficiency, fast response and control robustness at competitive price.Recently he has joined Protronic Far East Ltd, Protronic Group, as Strategic Business Partner driving the design and marketing of the Green Line Products in the company mainly system controllers, true sine wave converter and grid tie converter.

Company Profile

Protronic Group is an HK based electronic company with strong R&D, Engineering, Design and Manufacturing capacity in electronic products including power and energy products, automotive electronics and security products.

ProUser Green Power is a division of Protronic Group providing:

• Stand-Alone Technology in most of the developing countries;

• Grid Connected Technology in the developed countries;• Engineering, Procurement and Construction (EPC)

service and management for the MW-sized solar plant commissioned by our customer.

Solar System Configuration

STAND ALONE SYSTEM GRID CONNECTED SYSTEM

Solar Panel: Non Constant Input

Negative Voc temperature coefficentPositive Jsc temperature coefficent

Stand Alone Configuration

• MPPT System Controller• True Sine Wave Converter

MPPT Solar System Controller

MPPT Solar System Controller is a battery charger and load controller for stand alone PV (photovoltaic) systems. This controller features a smart tracking algorithm that maximizes energy harvest from solar panels. The controller also prevents over charge or deep discharge. It provides automatic load control for the external load connected to the controller.

MPPT Solar System Controller

• MPPT Solar System Controller optimizes battery charging process increases battery life, minimizes battery maintenance, and improves system performance. Moreover a software algoritm manipulates the current to give the perfect State of Charge (SoC) to the battery regardless the ambient condition.

MPPT Solar System Controller

• Maximum Power Point Tracking, referred to as MPPT, is an electronic system that operates the photovoltaic modules to produce maximum power. MPPT varies the electrical operating point of the modules and enables them to deliver maximum available power. The additional power harvested increases the current available for battery charging.

MPPT Solar System Controller

• MPPT solar system controller achieves the target to harvest 40% more power from the solar panel in comparison with the conventional controller

True Sine Wave Converter

• 12/24/48Vdc Automatic Detection Input Voltage

• THD very minimize; less than 3%• Max. Efficiency more than 90%• Easy Connection in Parallel when

the electricity needs increase• Simple Human Interface

Grid Connected Converter

• Solar energy is converted into electricity and fed into the public grid.

• Efficient, reliable, high power inverters are the heart of any PV system.

• The development of PV inverters is driven by new technologies, by innovative solutions, and by completely new answers. The result: highly performance mains-connected inverters, which interact optimally with all solar modules and smartly with all grid.

Grid Connected Configuration

Grid Connected Converter

• High conversion efficiency/boosting system with Smart Maximum Power Point Tracking function;

• DSP based fully digital control to operate sophisticated algorythm;

• High efficiency: 93% to 96%;• Power Factor close to 1;• THD according local regulations;• Voltage and Frequency fed according

local regulations;• Anti-islanding function;• Energy Monitoring via RS232, USB and

Wireless comunication• Long Life usage: MTBF > 100,000 hours

Key Product Issues

• Optimize MPPT algorythms

• High Frequency Transformer Technology offers maximum output in minimum space

• Grid monitoring has to be very accurate

• European approval IEC 61727, IEC 61000-3-2 and IEC 61000-3-3

• UL approval IEE 922

Grid Connected Inverter Topology

Grid Connected Inverter Topology

5kWp Grid Connected System

MW-sized Grid Connected System

Connection to the Grid

Optimization of power flow and transmission efficiency in weak distribution grids and micro-grids by means of cooperative operation of distributed power electronics units is becoming a big issue nowdays.

Connection to the Grid

Distribution grids are increasingly populated by a variety of renewable energy sources, which create new opportunities in terms of efficient use of energy and can also help to improve power quality. In fact, they are connected to the grid by means of Power Switching Interfaces (PSI) which are capable to control power flow and waveform of absorbed currents as well. They can therefore contribute to power flow control and power quality together with other power electronics units, e.g., passive filters, SVC (Static VAR Compensators) and APF (Active Power Filters). Of course, effective use of such distributed control capability requires cooperative operation of power electronics units and proper sharing of power flowcontrol and compensation duties.

Connection to the Grid

Although unbalance, reactive and harmonic compensation has been the subject of many studies and applications the problem is still open and becomes increasingly difficult and intriguing. In fact, reference is usually made to grids fed by power sources of large capacity, which impress sinusoidal and symmetrical voltages at the Point of Common Coupling (PCC). Nowadays, however, this is not generally true, since proliferation of small power sources and distorting loads may cause the grid to appear as a weak power source, characterized by non-negligible impedance, voltage asymmetry and distortion.

Contact us

Protronic Group

Unit 2504, 25/F Nanyang Plaza

57 Hung To Road, Kwun Tong

Kowloon, Hong Kong

Land Phone: +852-23308842

E-mail: walter@precisionhk.com