Performance optimization of Solar PV
plant Through Micro Inverter
Ashish VermaM.Tech (Energy System)500022066
University of Petroleum and energy studies
Power scenario in India Growing scenario of Renewable energy
UPES
► Renewable energy accounts for approximately 12.04% of a total 214.86 GW of power generation capacity installed in India.
► Demand for power in India has been increasing due to the rising population, growing economy, and changing lifestyles.
► Despite substantial capacity additions, the power sector is still in shortage of energy.
► Peak demand shortage averages around 9%.
► Renewable energy installed capacity was grown at a healthy CAGR of 19% over FY07-FY12
Source: MNRE, CEA & Economic survey of India 2012
58%
9%
1%
2%
18%
12% CoalGasDieselNuclearHydroRES
FY07 FY08 FY09 FY10 FY11 FY12
10.2 12.3 14.4 16.820
24.5
Growth of Renewable energy installed capacity in India
CAGR 19%
India is largest EPC sector in renewable energy
in the World
Installed capacity of 27.29 GW(up to feb2013)
various mission and state policies for
enhancing the power generation capacity
through renewable energy(NSM,NBMMP ,Gujrat Solar
policy2009 etc.)
Target of Renewable energy mix of 15 %
upto2017
Total installed capacity of Solar PV was 10 MW
before 2009 and now its reached up to 1440MW (feb2013)
Expected CAGR of installed capacity of Solar
PV is 47 % during the 2011-16
Source :EFYtimes, MNRE,PV- Magazine, NAPCC
Break Up of Renewable Energy
Growth rate of Solar PV UPES
68.27%
13.01%
4.63%
8.43%
0.35%5.30%
Grid Interactive Installed capacity (In MW)
Wind
Small Hydro power
Biomass Power
Bagasse Cogenera-tionWaste to power
Solar PV
Different type of Solar PV plant and his component UPES
Grid Connected System & Component 1. Module
2. Inverter
3. Transformer
4. Distribution panel
Off grid System & Component 5. Module
6. PCU ( Charger controller /Inverter )
7. Battery
8. Distribution Panel
Decentralized System Suitable for where grid connectivity is poor or grid is not viable
Best option for Rural Electrification
Grid connected Solar PV plant cost is 8
Cr/MWp
Land according to technology used
(Crystalline & Thin film)
Highest cost sharing by PV module is
around 43%
Source: CERC
Break up Cost of Solar PV plant UPES
43%
7%2%12%
13%
13%
10%
% Sharing of Cost/MW
Module
PCU
Land Cost
Civil and General Work
Mounting Structure
Evacuation cost up to Inter connection point
IDC & Con-tingency cost
CUF which is ratio of actual energy produced from the plant to maximum possible output during the year
Radiation of the Site - Responsible of energy generation through solar PV Primary requirement for design of power plant Data me be instant(Irradiance) or integrated(irradiation )Comparable result found the inaccuracy of 20-25%
Losses in PV system Which cause the power actually delivered to the grid to be lower than the power produced from PV moduleCable loss Power Inverter Dust on the Module surface Ambient temperatureVarying insolation level
Performance parameter of Solar PV plant UPES
Reflection lossdata show that the module faced toward the equator with tilt angle of latitude ,yearly reflection losses is 1 % relative to STC
Soiling LossOccur due to dust and dirt particles Losses are generally 1%Reduce the power capability
Mismatch Effect Losses due to series and parallel connection of Module Module don’t have identical property
MPPT LossExtract the max power from Solar PV
Inverter Efficiency Stand alone ,Grid tied Efficiency measure how well it convert the dc voltage into AC voltage Efficiency of 95-98 % Less efficiency at low power
Temperature and climate conditionPower decrease according to temperature coefficient
Typical value for Crystalline module is -0.4- 0.45%/°C
Typical value for thin film module is -0.24-0.25%/°C
Design parameter of Plant Minimization of ohmic losses
Selection of efficient transformer and Inverter
Mounting position –proper air ventilation required
Inclination angle –max radiation can be obtained by optimum tilt angle which is
determine by the latitude of location
Module power degradation due to ageing-0.50% reduction of power Per year
90% of the max power up to 10 years and 80% of the max power next 15 years
Ensure continuous and reliable operation
Generating maximum energy
Maximize the economic performance
Ensure better PR
Life expectancy
Long term commercial utilization of plant
Need of optimization and evaluation of the Performance ? UPES
It build into or attached to each PV module
Each micro inverter convert Dc from each module to AC ,ready for grid connection
directly
Allow Each module to be an independent ,standalone , Solar AC grid connected
system with optimized energy production output
Less space for installation
No handling to high DC voltage
No Issue of single point failure
Life is more 20-30 % than String inverter
Market Growth is around $14.8Billion*
Source: Bloomberg Energy ,NREL, Enphase
Micro Inverter -Technology
Activation Process
Array Gun
Center feed – separate the individual branch circuit current for protection with
OCPD(over current protection device )
Communication domain
Engage cable – connecting the Micro Inverter
LCF – when more than one communication domain is installed ,for reducing the
noise level
Micro Inverter- Inverter automatic detect the utility scale voltage and export power
the utility services , connected with CB
Micro inverter Sub panel
PLC
Transformer –use to connect the commercial PV project to utility grid
Micro Inverter Component
Micro inverter operate similarly to central inverter System
Connected on each individually module
Handle much less power than central inverter
Yes ,Micro inverter are better option for optimization
Improve the energy harvest
Increase reliability
Simplify design ,installation
Better monitoring of Individuals
Dynamic MPPT efficiency is around 99.3%
Integrated with PLC
Micro Inverter
Is micro inverter best option to optimize the performance ? UPES
Connection of Micro inverter Integrated with Solar PV Module UPES
Source :Enphase Energy
Deliver design flexibility
Integrated intelligence 24/7 monitoring analysis Quick and simple design ,installation and management Increase energy harvestDue to minimization of system losses due to DC-AC conversion
Cost effective Cost is 10-12% high comparable to Central or String InverterEnergy production 18-20% high , so cost effectiveness is justified
Limitless scalability Include main panel board of PV load center that feeds multiple micro inverter sub panel distributed across the system
Benefits of Micro Inverter over other Inverter
Isolating Communication devices Reduce the communication noise
Better individual Monitoring
Reliable
System availability greater than 99.8%
No single point failure of system
Safe Low voltage DC
Reduce fire risk
Source: Enphase energy, NREL
PV module with String & Central Inverter
PV module with Micro Inverter
Micro Inverter V/S String ,Central Inverter UPES
Buyers wants to know what would be the PBP of investment
Saving and PBP is vary according to location
Dependent on various factor like cost of electricity from the grid
Feed in Tariff
Subsidy
Capital cost
Unpredictable factor , like radiation that affect the amount generation of electricity
LCOE (Levelelized cost of Electricity) – best option to comparing the
lifetime system cost with total power harvested over the period of time help to
determine the ROI
Economics behind installing Micro Inverter UPES
LCOE takes account of
1. Capital Cost- module cost , cost of power conversion electronics, Installation
2. Power harvesting –the total power harvested from the system ,through its life
time and monetary value of each harvested kWh ,determine the financial return
3. Operation & Maintenance – Directly proportional to the system reliability ,if it
is difficult to locate the source of problem ,the time spent on locating the fault will
increase the cost
Low LCOE show that RE power production is cheep and close to achieving GRID parity
Power optimizer are also used for extracting the max power from Module ,but cost is
increase $200 per module and need of central inverter same
Capital Cost :System Rating -7kWp
Module cost per Watt-$2 ($14,000)
String Inverter Cost per Watt - $0.5($3,500) Micro Inverter Cost per Watt- $0.75($5,250)
Total =$17,500 Total=$19,250
Cost is 10% more than String inverter
Installation CostNo high voltage DC switch and wire
No need to allocate area for inverter in building
According to market survey installation cost for String inverter is $16,500 and for Micro
inverter is $12,500 for 7kWp plant
Offer saving of 24% in installation cost
Enecsys Case Study : Architecture Cost Evaluation
PV Evaluation Lab (PVEL), in association with NREL ,recently performed a series of
field test to measure the shade impact on solar array output.
Solar Micro inverter shows the higher output than a string inverter in certain cases
Perform in Light ,Medium and Highly shade – 4%,8%,12% increased energy harvested
by Micro Inverter
Solar power electronics ,Inverter ,Micro Inverter ,Power converter have a range of
obtaining Max power curve
NREL developed different type of standard test procedure for simulating PV
performance under shade
Source: NREL , PVEL, Enphase energy
Shade impact On Power Generation Through Solar PV
Experimental Case study - String & Micro inverter
Characteristics Curve of System with Shade effect
Source: NREL , PVEL, Enphase energy
Adopted MethodologyPerformance tested on two identical 8kWp Array
One connected with String inverter and another is with Micro Inverter
Tested under different 78 shaded test condition
Semi Transparent mess in Module
Mesh with transparency of 36%
Shade configuration time is around 20 Minutes
Performance is measured with the RGM (Revenue grade meter )
Result
Micro Inverter perform better in shading
String inverter stuck in the a local MPP causing current limited operation of the
system
NREL’s result show that the approximately 50% of the energy lost due to shading by
string inverter ,specially in light shade condition
Micro inverter increase the harvested energy 4%,8% and 12% in light , medium and
high shade condition
Result Summary with Graph
Inverter output V/S Shade area
Question & Answers
Thank You….