Tags from PV Design

Part 1: Commercial PV System Sizing and Design with SMA CORE1 Inverter

PART I

In view of the increasing number of PV commercial installations across the U.S., installers and contractors find themselves under constant pressure to complete more projects in less time. In order to achieve this, they must streamline the installation process while maintaining safety and quality standards.

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The first step of the process starts with design. While most of the time the objective is to maximize roof space in order to fit as many modules as possible, it is essential to plan ahead for service and maintenance, leaving enough space between strings of modules in order to allow easy access. Once the system layout has been determined, the equipment for the project must be selected. When choosing the right inverter for the job, one must consider more than just technical specifications. It is also important to keep he installation process in mind, under what conditions the inverters will be working, and all other major requirements of a commercial PV plant, including; monitoring systems, weather stations, string aggregation, shade mitigation, racking structures, and additional BOS.

When considering all these factors it is often difficult to find an inverter that can meet all of the required metrics for the integration. Fortunately, we have the tools and the solutions to help you design a successful project that can be carried out and completed within a tight deadline.

First, SMA’s free sizing and simulation tool, Sunny Design, allows you to size systems correctly by matching SMA inverters with PV curves, and to compare design alternatives with different inverters in order to be able to make the right decision not only based on energy yield but also on economics and architectures.

As an example, we sized a 67-kWp rooftop commercial system with Sunny Design. We designed two alternatives for this project; one with the Sunny Tripower TL-US and one with the Sunny Tripower CORE1 – the latest addition to our commercial solutions portfolio.  For this project, we designed a roof-mounted array with an East/West configuration and a 15o inclination.

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When used in the automatic design mode, Sunny Design will do all the calculations and can offer options based on profitability or energy yield. For the first alternative we have selected a design with two STP 30000 TL-US inverters. The suggested configuration for the array has three strings in parallel connected to each input of the inverter, meaning that we will need to incorporate DC combiner boxes in order bring the six strings into the two MPPT channels of the STP inverters. The results of the simulation, including current and voltage values, can be seen below:

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It is important to note the 1.1 DC/AC ratio of the design. High DC/AC ratios account for module degradation and potential higher energy yields during a calendar year.

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The higher integration of the CORE1 allows you to connect up to 12 strings to the inverter eliminating the need for additional BOS like DC combiner boxes. Thanks to its higher power rating of 50kW it is possible to reduce the number of inverters and the number of connections, improving the overall installation time.

When considering the specification of the PV plant it is clear that the advanced features of the CORE 1 align better with the requirements of the project.

Multiple communication channels allow for easier monitoring and commissioning. Although best practices for monitoring involve using a physical communications channel like Speedwire (SMA’s Ethernet based protocol) because of its reliability and higher speeds, WLAN is the better option when commissioning the inverter on site. It will allow direct communication between the inverter and any smart device that can connect to a wireless network and access the WebUI through a web browser.

In part two of our series, we will outline the benefits of the CORE1 for weather data integration as well as the advantages of using Sunny Design.

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Join SMA and Aurora Solar for Discussion on Residential PV Optimization

SMA America and Aurora Solar are partnering to bring you a Greentech Media webinar on August 31 at 2:00 p.m. ET. Speakers include SMA America Director of Marketing Brad Dore, SMA America Senior Technical Training Mike Mahon, and Aurora Solar Chief Operating Officer Samuel Adeyemo. 

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Real-World Follow-Up: Sunworks Utilizes Sunny Boy-US for Easy Installation

Our most recent Tech Tip illustrated how quick and easy it is to install the new Sunny Boy-US inverter and here is real-world proof. Check out this video of Sunworks installing a Sunny Boy-US residential system in no time at all, from racking to inverter connection.

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Tech Tip: Sunny Island Battery Commissioning

Commissioning a new lithium-ion battery within a Sunny Island system takes only minutes. In this Tech Tip video, the SMA Solar Academy demonstrates the simple commissioning procedure for a Sunny Island system with a battery that uses an external battery management system, or BMS.

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Anheuser Busch Distributor Raises a Cold One to Distributed Solar

Sunny Tripower Commercial System

When engineering, procurement and construction company Solar Energy Management designed the largest rooftop installation in Florida, two things were especially important: that the components be industry-leading and made in America.

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6.8MW Chilean solar plant expected to operate at grid parity

Sunny Central 760CP XT

Photovoltaics are becoming a reality in Chile, one of South America’s fastest-growing emerging markets with a high potential for solar energy generation. The impending construction of two solar facilities in the Coquimbo Region stands as evidence that the area is ready for large-scale solar technology to offer cost-competitive electricity for the regions inhabitants.

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Properly sizing a PV inverter breaker

PV Inveter Breaker - SMA Inverted

Believe it or not, code references for determining the calculation to adequately size a PV inverter breaker are longer than the calculation itself. Don’t be intimidated into making a costly mistake when designing a customer’s solar system.

The calculation is simply the maximum output current of the inverter multiplied by a 125 percent safety factor, then rounded up to the nearest breaker size.

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Calculating Max PV Voltage is Not Scary

Calculating Max PV Voltage is Not Scary

In 2008, the National Electrical Code (NEC) added a second paragraph to 690.7(A) stating, “When open-circuit voltage temperature coefficients are supplied in the instructions for listed PV modules, they shall be used to calculate the maximum PV system voltage as required by 110.3(B) instead of using Table 690.7.” This addition was made because Table 690.7 is very conservative and the temperature coefficient will provide a more accurate voltage increase.

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Navigating the Changing Requirements of PV Interconnection, Operations and Metering

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The solar industry is changing rapidly; new policies, regulations and requirements are being implemented at all levels of governance. As PV penetration increases, the need for changes in regulation follows the need for grid safety, stability and increased PV expertise within utilities and grid managers. Examining these trends from a global, national, statewide and local perspective will be critical to understanding how to navigate future regulations in an effort to achieve grid stability and the continued growth of PV.

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Optimization of Utility-Scale PV Systems

Project developers, EPCs, utilities, financiers and other PV project stakeholders are relying on utility-scale photovoltaic systems for long-term energy production and profitability. These systems have proven to be viable sources of electricity as their power-producing capacity is realized.

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The Main Event – A look back at SPI 2014

The lights shined bright and the excitement flowed from the center of the ring—Solar Power International 2014 attendees flocked to The Main Event in Las Vegas to see SMA’s line of champion inverters. From October 21–23, the Las Vegas strip embraced solar power to take in the industry’s latest and greatest.

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Get it while it lasts — Free Sunny Boy 240-US Module-Level Monitoring for Life!

SMA Sunny Portal

Module-level monitoring offers users the most granular reporting possible – and now SMA is offering it at no cost for the life of new Sunny Boy 240-US systems purchased throughout the remainder of 2014.  The monitoring package is exclusive to micro inverter and Multigate packages and the system must be purchased by December 31, 2014.

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