copyright ©2018 outback power technologies, inc. all rights · 2019-01-29 · with skybox •...

Copyright © 2018 OutBack Power Technologies, Inc. All Rights Reserved.

Retrofitting Grid-Tied PV Systems2019 AEE Dealer Conference

Paul DaileyOutBack Power Technologies

Copyright © 2018 OutBack Power Technologies, Inc. All Rights Reserved.

Agenda

• Why Add Batteries?

• Replacing the GT Inverter

• AC Coupling

Copyright © 2018 Outback Power Technologies, Inc. All Rights Reserved.

Why Add BatteriesThe Business Case for Retrofit

Customer acquisition is a leading cost for PV installation

• Existing customers already understand benefits of solar

• You don’t have to educate them

• You already have a relationship with your past customers

• You already have names and contact info

• They already know what to expect

• Existing PV system owners want backup

• Increasing outage frequency and duration

• Increasing awareness of battery options


Why Add BatteriesWho is a Good Candidate for Battery Retrofit

Good Candidates

• System owners

• Power outage victims

• Increased severity/frequency of storms

• Increased severity/frequency of wildfires

• Increased proactive utility outages

• Backup fits well into a disaster-preparedness theme

• Families with young children

Not-so-Good Candidates

• Lease or PPA customers

• Unless you own the system

• Renters/Landlords

• Landlords have little incentive to invest in backup for their renters

• High-maintenance customers

• Batteries introduce some user requirements, so a good rapport is vital


Why Add BatteriesBusiness Benefits

• Reduced origination costs

• Call on existing customers

• Referrals from installers who don’t do batteries

• Customer referrals for PV jobs will likely refer you for battery jobs

• Backup can be part of a complete-solution brand of energy services

• Keep crews busy

• No additional licensing required for battery systems

• OutBack’s Energy Storage for Solar Professionals training

• 4 days of hands-on learning

• Field-proven instructors and techniques


Move some or all of the existing PV array to a SkyBox or FM100

Move the Array

Retrofit Option 1Replace the grid-tied inverter


Replacing the Grid-Tied InverterWith SkyBox

• Strings of 9 to 13* modules can be moved directly to the SkyBox PV inputs

• Up to 6.5 kW of nameplate PV capacity per SkyBox

• Larger arrays can be divided between the GT inverter and SkyBox

• Rapid shutdown requirements still apply

• String-level shutdown available from OutBack

• Module-level shutdown with Tigo or IMO, etc.

*Subject to module specs and climate


Replacing the Grid-Tied InverterWith FM100

• Strings of 3 to 6* modules can be moved to the FM100

• Up to 6 kW of nameplate PV capacity per FM100

• Larger arrays can be divided between the GT inverter and FM100

• E.g. reconfigure one string for FM100 and leave rest in place

• AFCI and Rapid shutdown requirements still apply

• String-level shutdown available from OutBack

• Module-level shutdown with Tigo or IMO, etc.

*Subject to module specs and climate


Replacing the Grid-Tied InverterAdvantages and Disadvantages

Advantages

• Best battery management

• Most efficient charging

• Best approach for battery longevity

• Can disable charging from grid

• Simpler single-vendor system

• Easiest generator integration

• Built-in generator port

• No external transfer switch needed

Disadvantages

• FM100 may require some array reconfiguration

• May trigger changes to interconnection agreement

• Some AHJs consider a new inverter the same as a new system


Use existing grid-tied inverter to charge batteries and run loads during an outage

AC Coupling

Retrofit Option 2AC Coupling


AC CouplingThe starting point: Typical grid-tied PV system

• Output of GT inverter connected to main panel/load center

• Grid provides voltage waveform

• GT inverter shuts down during grid outage


AC CouplingAC Coupled system with active PV and grid

• Output of GT inverter connected to Radian output

• Protected loads can be served from Radian, GT inverter or grid

• Battery charged from GT inverter or grid

• Surplus PV can be exported only if Radian is in Grid Tied input mode and AC Coupling Frequency Shift is enabled


AC CouplingAC Coupled system without active PV

• Protected loads served by grid via pass-through

• Main panel loads served by grid

• Battery can be charged from grid using Radian charger


AC CouplingAC Coupled system during grid outage

• Radian automatically isolates itself, GT inverter and protected loads from the grid to prevent back feed

• Protected loads served by GT inverter and/or Radian

• Main panel is not served

• Battery can be charged from GT inverter surplus power using Radian charger

Grid

Loss


AC CouplingAC Coupled system on a dark and stormy night

• Radian automatically isolates itself, GT inverter and protected loads from the grid to prevent back feed

• Protected loads served by Radian and battery

• Main panel is not served

Grid

Loss

PV

Loss


AC CouplingRadian with frequency shift

• Radian can incrementally step up output frequency as battery reaches full charge

• Special Radian firmware update required to enable

• Target battery voltage, current limit and time increments are programmable

• Radian will increase frequency when:

• Battery voltage exceeds active charging voltage target by 0.4 VDC or more

• Follows Absorb and float voltages just like grid or generator charging

• AC charge current exceeds AC charge current limit setting

• Radian will continue to raise frequency until:

• Battery voltage and current are within set limits

• Rule 21-compliant GT inverters will modulate their output as frequency rises

• Output frequency exceeds 64.5 Hz and GT inverter shuts down

• All IEEE 1547 compliant GT inverters are required to shut down at this frequency


AC CouplingRadian with frequency shift - setup

1. Download Radian AC Coupling firmware files to SD card and install from MATE3s Main menu

• Be sure MATE3s has latest firmware version

2. Select Settings from MATE3s then Main Inverter AC Coupling

3. Change AC Coupling from N to Y, and set Freq Shift Response Time (0.02 to 5.0 seconds) as desired

• This setting adjusts delay in frequency steps between 60.0 and 64.5 Hz.

4. Press the UP key to move back to Inverter Menu

5. Program Absorb and Float charger settings to battery specifications

6. Go to Grid Tied settings in Inverter menu to adjust SellRE setting -default is 52.0 volts

NOTE: SellRE is the voltage target once Absorb and Float timers have run out. Setting SellREequal to Float will keep the batteries fully charged during emergency backup operation. Most lead acid batteries can operate safely at Float voltages for extended periods. Consult battery manufacturer recommendations.


AC CouplingRadian with frequency shift – Technical considerations

• Radian should have at least 25% higher nameplate capacity than grid-tied inverter

• GS8048A can AC couple up to 6 kW GTI

• GS4048A can AC couple up to 3 kW GTI

• A 25-A breaker/disconnect is recommended between the GT inverter and Radian AC output bus

• Enables isolation for troubleshooting and/or overload protection

120V/240V GRID FEED

120V/240V

200 Amp Main Service M

200A Disconnect120V/240V

Critical Load Panel

AC In Bus

50A DPST

DC Disconnect175A SPST (2x)

AC In BUS Gen

50A DPST

GSLC Load Center

AC Out BUS Grid

50A DPST

DC Neg

GS8048 Inverter

6kW PV Array

6kW Grid Tie Inverter

12V12V 12V12V

200A Disconnect

50A 120V/240V

25A DPST

String Combiner


AC CouplingRadian with frequency shift – Generator integration

• Must prevent GT inverter from back feeding generator

• Automated safety relay approach:

• Locks out GTI connections with either manual or auto gen start

• Uses generator live AC to activate 2PDT relay


AC CouplingRadian with frequency shift – Generator integration

• Manual transfer switch approach

• Connect generator to the AC Gen Input terminals in the GSLC load center

• Install 25-A DPST switch on GT inverter output

• Open GT inverter circuit prior to starting generator

GTI disconnect must be opened before starting generator.


AC CouplingAdvantages and Disadvantages

Advantages

• Makes use of existing hardware

• GT inverter, PV array and RSD

• Less disruptive installation

• Little to no time on roof

• More efficient export

• GT inverter efficiency is not impacted during normal operation

Disadvantages

• More difficult to integrate with a generator

• Requires additional hardware and careful design work

• Difficult to ensure non-export when grid is active

• Less efficient battery charging than DC coupled PV charging


AC CouplingCompetitive Advantages

Competitive Advantages

• Multiple Voltage and Current Protections to Safeguard Batteries

• Uses Absorb and Float voltage targets as in normal grid connected charging

• Uses adjustable SellRE as voltage protection target if Absorb and Float timers are zero

• The AC Charger Input Limit is used to protect batteries from overcharging

• Freq/Watt compatibility allows GTI to “feather back” output under closed loop control

• Best generator protection and control

• Optional relay provides automatic protection for generator (as allowed by local jurisdictions)

• Inverter generator input port eliminates need for external transfer switch

Thank you for your time.

www.outbackpower.com

copyright ©2018 outback power technologies, inc. all rights · 2019-01-29 · with skybox •...

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