How To Choose And Care For Your Solar Inverter
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How to Choose and Care For Your Solar Inverter
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Inverters are among the most important components in a solar installation. They are the brains of the system, so it’s equally important to correctly select and care for them. But how do you properly size an inverter, or determine its actual rating? What kind of maintenance and inspection should be included in a proper operations and maintenance plan? And what are some of the signs that your project’s inverters may be malfunctioning? Join us in a special 1-hour webinar where we ask expert installers these questions to find out.
Transcript of How To Choose And Care For Your Solar Inverter
How to Choose and Care For
Your Solar Inverter
Webinar Sponsored By:
Moderator
Kathie ZippSolar Power World
Presenters
J.S. RoyBeacon Power
Services
Daniel IthurburnMartifer Solar
Module Level Power Electronics
• Microinverters (DC to AC)o Examples: Enphase Energy, SMA, Solar Bridge, Enecsys, …
• DC Optimizers (DC to DC)o Examples: SolarEdge, Tigo, …
Why?• Benefits:
o Shade toleranto Fault toleranto More flexibility in designo Granular data & lots of it!
• Costs:o The cost!o Faults are obvious*
Sizing• System Specs:
o 260 W solar panels • 260W @ STC / 232.5 W @ PTC
o 96.5% microinverter efficiency
• Do the Math:o Max power in for max power out:
• STC: 260W x 96.5% = 250.9 W AC
• PTC: 232.5W x 96.5% = 224.4 W AC
• Consider your location!
O&M: At a High Level• Monitoring
• Preventative Maintenanceo Solar panel cleaning
• Unscheduled Maintenance
Monitoring• No more weather
stations!
• Data, Data, & more Data!
Preventative Maintenance
• Little to none (depending on the technology used)o Microinverter has noneo DC optimizer has some for the inverter
• PM should still be performed!o AC interconnectionso Rackingo Solar panelso Etc.
Unscheduled Maintenance
• Issues are immediately obvious!• Fault has little impact on the overall system• Truck roll is scheduled
• Remote troubleshooting is possible in ~90% of caseso Truck will have necessary replacement parts
Take Aways• Benefits & Costs of operating one of these
systemso Is the ease of operation worth the added upfront cost?
• Maintenance of Module Level Power Electronics systemso Use the data to tailor your maintenance strategy
Choosing and Maintaining String and Central Inverters- A Designer’s Perspective
Introduction
• Lead Design Engineer• Array Troubleshoot Consulting
• Project Feasibility Reporting
Inverter Reliability
• Failure Rate• The Bathtub Curve• Infant Mortality Rate• Useful Life• MTBF
Failure Rate -
The frequency with which an a engineered system fails as defined by Reliability Engineering
Bathtub Curve
InfantMortalit
y
MTBF-
Is NOT the average life span of a product, but rather the inverse of the failure rate during the Useful life period.
= .01
Third Party Evaluations-
Ask the Manufacturer for any reports availableUse Test Data from readily available sources (ie: websites, magazines; studies)If unavailable, consider purchasing reliability testing.
Inverter Maintenance
• Commissioning• Preventive Maintenance• Monitoring
Inverter Commissioning
A Proper Commissioning Procedure done by a trained professional will reduce the likelihood of infant mortality of the inverter
Inverter Commissioning
Thermal Imaging
Torque Checks
Performance Verification
Preventive Maintenance
• MTBF Studies include all Preventive Maintenance and consumable parts
• Follow the Maintenance Procedure in the Inverter’s Manual.
Preventive Maintenance
• Recommission the Inverter
• Note any abnormalities in the inverter and Repair as Necessary.
• Keep a log of repairs that feed back into the inverter selection process.
Monitoring
• Setup alarms to your O&M personnel using specific criteria.
• Perform Spot Checks for Array Performance
Picking the Right Inverter
• Environmental Constraints• Choosing a DC/AC Ratio• Inverter Efficiency
• Advanced Utility Features
Environmental Constraints
• Use ASHRAE to determine the design temperature
• Check the spec sheet against the design temperature, note any efficiency derates at higher temperatures
• Communicate with the manufacturer when working on the edges of the inverter capability
Environmental Constraints
• High Humidity Environments will lead to higher corrosion rates. Consider Humidity Controllers
• If an area is susceptible to flooding or high snow fall, Consider increasing the enclosure rating of the Inverter.
Choosing a DC/AC Ratio
PVSYST will quickly calculate the overload losses due to inverter overload in the first year
Choosing a DC/AC Ratio
• Pushing up the DC/AC Ratio often helps the overall financials of the Project in terms of ROI
• Tiered Electricity Rates may reduce the need of overload losses by offsetting the initial costs with increased efficiency during high tiered months
Choosing a DC/AC Ratio
• Inverter Manufacturers have a limit on how much overloading they will allow
• Overloading an inverter in a high temperature environment may result in decreased performance and useful life
Inverter Efficiency
• It is easy to say that given the same price and quality always choose the highest efficiency inverter
• How do you compare when the costs are not the same?
Inverter Efficiency
Using CEC Weighted Efficiency
Inverter Efficiency
Using PVSYST
Inverter Efficiency
Additional Advantage of Increased Returns after ROI has been reached for the useful life of the inverter.
Thank YouReferences:
1) Lewis, E.E. Introduction to Reliability Engineering. Hoboken: John Wiley and Sons, Inc, 1996 Print
2) Quinn, Connor. 61673-fig. 2010. Electronic Design Europe. Graph. 2/19/2014
Questions?Solar Power WorldKathie [email protected] Phone: 440.234.4531Twitter: @SolarKathieZ
Beacon Power ServicesJ.S. [email protected] Phone: 773.354.2100
Martifer Solar Daniel Ithurburn [email protected] Phone: 310.663.2750
Thank You This webinar will be available at
www.solarpowerworldonline.com & email
Tweet with hashtag #SolarWebinar
Connect with Solar Power World
Discuss this on EngineeringExchange.com
