Commercial PV Projects with AEE Solar Glenn Hall AEE Applications Engineer 1/26/2019
Seminar Discussion Topics Considering 60-cell vs 72-cell modules for Commercial PV Projects • Trends and developments for Commercial PV Systems • Sizing arrays with regards to Inverter capacity • Optimal tilt of arrays on Commercial Projects • NEC 2014/2017 Rapid Shutdown for Commercial Projects • ‒ NEC2017 Module Level Requirements – Jan. 1, 2019! Trends and developments for Commercial PV in 2019 • ‒ Inverter Advances Ballasted and Metal Roof Racking Systems • Example of maximizing output of a ballasted commercial PV system • New Aerocompact Metal Roof offerings • ‒ New! SnapNrack Ultrarail for Commercial Roof Projects Benefits of Commercial PV Monitoring • Commercial Ground Racking Solutions • Aerocompact Ballasted Ground Mounts • New! PLP Power Peak Ground Mount System • Benefits of Commercial PV System Monitoring • Tax Credits – ITC and MACRS Depreciation •
60-Cell vs. 72-Cell Modules Considerations with using 72-Cell modules for Commercial Projects Spike in demand for 72-cell modules! Tight supply, due to drop in ITC at end of 2019. o Last year, projects with long timelines benefited from easier sourcing of 60-cell panels o 60-Cell modules often are not much higher cost per watt than equivalent 72-Cell modules o Minimum order quantities often apply for 72-cell panels – full pallets or containers o Module power densities are typically higher using 60-Cell modules o PERC and Split-Cell options increased power densities for both 60 and 72-cell modules o 72-Cell panels may be restricted in areas with heavy snow load, or need Alpine Brackets o Two people often required to handle 72-Cell modules, 60-cell panels are one person o More aesthetic options available for 60-cell modules, if this is a customer requirement o 60-Cell Modules (typical) 72-Cell Modules (typical) Polycrystalline – 270-300 Watts Polycrystalline – 335 to 350 Watts • • Monocrystalline – 300 to 335+ Watts Monocrystalline – 350 to 380 Watts • • High Efficiency Mono – 350+ Watts High Efficiency Mono – Not Typical • •
Commercial PV Design Trends Higher DC to AC inverter load ratio ‒ <120% DC:AC in the past was regarded as the PV industry standard ‒ 130% to 135% is becoming much more common ‒ Inverters such as SMA Core1, Fronius Symo, and SolarEdge inverters, can utilize high DC to AC Ratios PV in designs that can be up to 150%! • A 50kW inverter could be used for up to a 75kW DC Solar Array ‒ Inverters can reach peak output earlier in the day, and minimal clipping during high irradiance is allowed. Inverters are not damaged by the PV Array. ‒ Fewer inverters needed for given site. Results in lower cost to purchase and deliver, and install. Also lower cost to maintain, service, and warranty. ‒ More kWh can be generated at the site with lower overall costs, considering materials, install labor, BOS, and maintenance. ‒ This results in lower cost per generated kWh for the PV system. High tilt angles on commercial projects are not always ideal ‒ Higher tilts angles results in larger inter-row spacing to prevent shading ‒ High percentage of net-metered solar production occurs during summer months ‒ Therefore, lower tilt angles allow larger PV arrays and more net energy production ‒ East/West racking solutions eliminate inter-row shading. ‒ Lower tilts and E/W maximizes module density; lower install cost and ballast weight ‒ Some considering West facing arrays to avoid higher TOU utility rates
Rapid Shutdown Considerations NEC2014 690.12(B)(1), the PV Array Boundary for limiting voltage for • controlled conductors is 10’ Applies to all energized DC conductors on or inside of a building • Conductors outside this boundary must be under 30 volts in 30 seconds • This allows first responders to de-energize the high voltage conductors quickly • Roof Mounted Commercial inverters within the PC Array Boundary met • NEC2014, but now do NOT meet NEC2017 code. Free Standing SMA Core1 commercial inverters easily located next to a PV Array • Other commercial inverters placed on ballast racks • Some 3 rd party String Level RSD devices available • Examples: Midnite Solar LSOB, Birdhouse with Shut Off Boxes, Innovative Solutions • NEC2017 code reduces the PV Array Boundary to 1’, and limits maximum • voltage allowed within the PV Array to 80 VDC. NEC2017 shrinks the boundary for controlled conductors to a 1’ perimeter • Conductors outside this boundary must be under 30 volts in 30 seconds. • Jan.1, 2019 – NEC 2017 690.12(B)(2) becomes effective • Voltage within the array boundary must be under 80 volts in 30 seconds • In essence, this requires Rapid Shutdown at the module level • Two module/one input optimizer solutions may be over this voltage, coldest day! •
NEC2017 Compliant Module Level RSD Options Meeting NEC2017 Module Level RSD requirements after Jan.1, 2019 • Tigo TS4-F MLPE – Shutoff under each module, with Sunspec inverters • SMA Residential inverters with -41 • SMA Commercial Core-1 inverters with -41 • Fronius Symo Advanced Commercial inverters as examples • No signaling Gateway or additional wiring needed, powerline communications • Solar modules with Maxim optimized junction boxes • Rapid Shutdown Functionality built into module junction box • Used with inverter manufacturers with SunSpec powerline communications • Tigo TS4-S or TS4-O optimizers, with Cloud Connect and Gateway • Enhanced range of rooftop Gateway makes deployment easier • Monitoring (TS4-S/TS4-O) and Optimization (TS4-O) added functionality • IMO FireRaptor RSD • Two panels served with each MLPE Device • Separate Emergency Switch, AC Powered • Midnite Little Shut Off Box (LSOB) • Transmitter placed around inverter output conductor • One LSOB receiver under each module for NEC2017 • Only one LSOB receiver needed for states still on earlier code cycles • Separate Bleed Down Unit also available for inverters that do not dissipate • voltage SolarEdge single panel optimizers (P320/P370/P400/P505) or commercial • optimizers that have two inputs (P800P/P860) Enphase IQ/IQ+/IQx microinverters • Traditional string inverters may become limited to being used on carports and • for ground mount PV Arrays NEC2014/NEC2017 Rapid Shutdown requirements are only required for roof • mounted solar arrays
NEC Adoption Map – 1/1/2019
NEC Adoption Map – 1/1/2019
SMA Tripower Core1 – 50kW Inverter • • • • • • • • • • • •
SolarEdge – Commercial Inverters
Enphase IQ for Commercial Projects Enphase IQ microinverters • Enphase Energy’s 7th generation microinverter • IQ7 for 235-350W 60-cell modules • IQ7+ for 300-440W 60 and 72-cell modules • IQ7X for 96-cell modules, (SunPower and • Panasonic) Two wire IQ Trunk Cable system, reduced • components, resulting in lower costs 25-year warranty product in US • Roof top Aggregator – Acts as easy plug and play • roof top combiner Envoy IQ for both 1P-120/240VAC and • 3P-208VAC or 3P-240VAC projects High CEC Efficiency rating of 97.5% • Next Gen - IQ8 to be released later this year! • Commercial Applications • Module level optimization, with high DC to AC ratios • UL1741-SA Compliant for new utility requirements, • and Smart Grid Ready Built in module level NEC2017 • Rapid Shutdown compliance Ideal for smaller commercial projects, as well as • larger ones with broken up arrays that may be difficult to meet Rapid Shutdown compliance. Applicable to 3P-208-WYE or 3P-240-DELTA grids! •
Commercial Rooftop Racking Flat-roof arrays using ballasted racking solutions • • Quick to design & install • Fewer materials needed than rail-based systems • Minimizes or eliminates roof penetrations • Avoids re-sealing • Easier servicing of roof • Less roof warranty issues Limitations of ballasted systems • • Seismic-related building codes may mandate some penetrations • Not suitable for roofs with greater than 5° slope • Not suitable for roofs over 50’ high • Wind exposure drives ballast and module tilt limitations • Be sure that designer and/or supplier uses correct wind loads, exposure categories, and risk factors!
Penetrating vs. Ballasted Penetrating Racking Ballasted Racking Roof penetrations into roof Weight of array plus additional • • structure anchors PV array ballast anchors PV array Roof penetrations must be Few to no roof penetrations • • properly sealed for array life required to anchor array Higher tilt angles are possible Tilt angles typically <10° to • • to increase module efficiency minimize wind effects Can be installed on pitched or Pitch of roof limited depending • • flat roof surfaces on racking solution Lower array weight than Higher roof loading due to • • ballasted, less roof dead load ballast weight, higher dead load Roof maintenance requires Array can be more easily • • removal of array racking and removed and reinstalled for roof re-installation of penetrations maintenance Easier Wire management and Special consideration to wire • • MLPE Attachment Options management and MLPEs
Recommend
More recommend
