Reducing Balance of System Costs Using Smart Modules. How Smart Curve Technology Increases String Length and Speeds Installation Time

Transcription

1 Reducing Balance of System Costs Using Smart Modules How Smart Curve Technology Increases String Length and Speeds Installation Time

2 Reducing Balance of System Costs Using Smart Modules: How Trinasmart Technology Increases String Length and Speeds Installation Time The price of solar continues to drop and the industry continues to grow. This is why solar panel manufacturers and component makers like Trina Solar and Tigo Energy are hard at work looking to squeeze every last penny of efficiency out of the whole system cost. One way to do this is to increase the number of modules that are in a string. Trina Solar and Tigo Energy have found a way to do this using a new technology called Smart Curve. Smart Curve is a patented technology that reduces the maximum operating voltage of a solar module. This increases the number of modules that can be connected in series by 30% while remaining within international safety compliance. This is similar to the benefits of moving from a 600V to 1000V system, since the amount of components per installed Watt is reduced. More kw/string. More kw/inverter. Increasing the number of modules in a string means that installers can install fewer strings per installed Watt of nameplate power. Having fewer strings means fewer combiners, fuses, disconnects, DC feeders etc. per Watt. This reduces installation time and cost, allowing installers to complete projects with fewer components, more quickly, and at around $0.05/W lower cost. Contributors: Jing Tian, Director Product Marketing, Trina Solar & James Bickford, Director Global OEM Channel, Tigo Energy This document is intended for education and redistribution Please feel free to share. Please consider the environment before printing. 2

3 How Smart Curve works to increase the string length The IV curve of a Trinasmart 60-Cell module TSM-245 PA05.25 with Smart Curve is shown in comparison to a standard Trina module TSM-245 PA05. In the IV curve of a standard module, the Voc (or Open Circuit Voltage) is approximately 37.5V at standard testing conditions. National Electric Code requires system designers to use the coldest day of the year to determine the modules maximum voltage. Since the majority of systems in North America have minimum temperatures around -10º C, a system designer must use 42V as the max voltage. I-V CURVES OF PV MODULE TSM-245 PA I-V CURVES OF PV MODULE TSM-245 PA05 Trinasmart has a max voltage at -10C of 32.2 whereas a traditional module has a max voltage of 42. 3

4 When designing a system for North America, installers typically have a 600V maximum safety rating. Dividing the voltage limit by the module s max voltage yields the number of panels that can fit in a single string and still comply with NEC code. For the 245W panel above a system designer can install 14 modules (600/42 = 14). With Smart Curve, the maximum voltage can be programmed in the factory so that the Voc is significantly lower. Trinasmart is programmed to 32.5 V and this does not change with temperature. This means that the Voc of the module is 32.5 V whether at 25º C or -10º C. It also means that for a system of 600V a designer can wire 18 modules in series (600V/32.5V), which is a 36 percent advantage over a traditional configuration. This benefit is also true in a 1000V system, where the Smart Module array would enable 25 modules connected in series versus only 19 modules in series for traditional modules. Since the voltage at max power of the module is 6% percent lower than the new voltage limit, this feature is only active when a system is off or the inverter is not drawing current. Only a few times a year, when the Vmp of the module increases to 32.5V or above (on very cold days), will the feature require the optimizer to limit voltage. Even on these days the module will not lose power, as the Smart Module simply raises the amperage from that module and keeps the voltage at 32.5V. 4

5 The Trinasmart Approach The great thing about this patented technology is that it is fully certified and compliant with existing NEC and IEC safety code. It provides the same benefit for 600V and 1000V system designs. Designers and installers can increase their modules per string by roughly 30 percent over traditional designs in either voltage environment. This reduces the number of balance of systems components per string by around 25 percent and makes install times 25 percent faster. This translates to lowering balance of system costs by around $0.05/W of savings for a typical commercial array in North America. This doesn t even include 3% energy yield boost. Smart Curve technology is now available in Trina Solar s Trinasmart line of panels. For more information, please visit or Contributors: TBD This document is intended for education and redistribution Please feel free to share. Please consider the environment before printing. 5

6 Appendix A Key Criteria Worksheet for Photovoltaic System Specification This worksheet will help you evaluate your options, and show you how Trina Solar compares to other offerings. Table 1: PV System Considerations for Your Facility Considerations Trina Solar Solutions Roof load capacity The Trinamount solar system is between 4-6 PSF, making it suitable for most roofs. Shade No PV panel works well in full shade, but Trina panels feature cell wiring that minimizes the effect of partial shade on overall array performance. Additionally, Trina s Trinasmart line of products allows for shade mitigation and efficiency gains through module-level optimization and system monitoring. Roof Area & Orientation Few roofs are completely free of obstructions and structures. The Trinamount III system offers maximum flexibility in panel placement, because the individual panel mounts are adjustable and do not require a minimum block (number) of panels. Energy demand & yield Commercial buildings typically use the most energy during the day. PV panels produce electricity exactly when it s needed. Trina s new Honey panels are among the most efficient commercially-available panels. They offer 15.9% efficiency and a lower NOCT value, which means better performance in hot weather. As a result, the Trina Honey panel has a performance ratio 3% to 4% higher than its nearest competitors. Additionally, many commercial buildings face roof area constraints. The Honey panel s world-record efficiency ensures the highest power density per dollar invested. Feed-in tariffs & tax incentives The additional energy produced by Trina panels means additional net return to you, in the form of feed- in tariff or incentive payments. Please ask a Trina Representative for actual yield studies against competitors in various global installations. Seismic & environmental factor In seismic areas, the TrinaMount system can be more easily secured with additional brackets than competing racking alternatives. PV installation security In general, rooftop systems are more secure than ground mount systems, but Trina takes it a step further by using a unique integrated attachment which rquires a special tool for assembly and dis-assembly. Roof age Ideally, you will install PV panels over a new or nearly-new roof. If this is not possible, Trina s easy-to-use Trinamount III system means fast panel removal and replacement. 6

7 Table 2: PV Panel Criteria Considerations Trina Solar Solutions PV Panel Specifications You should look beyond nameplate wattage ratings, and instead evaluate the NOCT and lowlight performance. Power ratings at NOCT are a closer estimate of real-world performance. Your panel vendor should also be able to provide you with power ratings at reduced illumination levels. Most PV systems operate most of the time well below the nominal 1000W/m2 that is used for the name plate rating. You should also look at the power rating tolerance. Trina rates its panels with a 0% negative tolerance in other words, a panel rated at 240W will produce at least 240W, probably a little more, but not less. PV Panel Certifications Panels are expected to last 25 years or more. Be sure the panel you choose has been tested and certified by a reputable third-party test agency. Every panel Trina offers has been certified by Underwriters Laboratory (also CSA, TUV, and IEC) to UL standard PV Panel Engineering Reports In addition to certifications, you should select a panel for which there are third-party engineering reports. Trina Solar has such a report from Black and Veatch, available upon request. Power Degradation & Warranty A slight loss of power over time is normal. While most vendors use a stair-step model, Trina offers an industry-leading linear power warranty. The module may lose up to 2.5 % power in the first year and thereafter, it may lose up to 0.7% per year, resulting with 80.7% at the end of the 25 year warranty. Panel Engineering Documents Trina supplies complete, CAD-compatible engineering drawings for all aspects of the panel design. Trina also supplies a valid, verified energy model forecast, complete installation training support, and maintenance recommendations. Fire Trina panels do not contain material (e.g. cadmium or other precious metals) that produce highly-toxic byproducts in the event of a fire. Aesthetics Trina offers panels with a smooth black surface across the face, with very thin grid lines. Square cells mean there are no gaps at corners. Furthermore, the Trinamount system holds the panels in neat rows and flows with the roof surface, resulting in a more organized array and attractive appearance. 7

8 Table 3: PV Panel Criteria Considerations Trina Solar Solutions Mounting System vs. Roof Type Trina has three types of Trinamount system. Each is specifically engineering for a particular roof type. So- called universal mount systems often require more work and more roof penetrations. Effect on roof drainage Some mounting systems are designed to sit flat on the roof and be held in place with ballast. These systems usually block the flow of water and create long-term roof drainage and maintenance problems. In severe cases, the excess water can overload the roof. Roof inspectability & Maintainability It s important to select a panel mounting system that lets you gain access to an area of roof, should maintenance be required. The Trinamount III system makes it easy to remove a single row of panels, without disturbing the rest of the array, and with minimal impact on overall energy production. Rooftop obstructions The Trinamount III system makes it easy to design around obstructions. You can omit a panel, or position one row offset from others. This design flexibility is not common among other racking alternatives. Roof material compatibility Trinamount III has been expressly engineered to work on low-slope commercial roofs. It is compatible with all types of membrane roofs and mod-bit roofs. Rooftop integrity Trinamount III systems can be ballasted, with zero penetrations, or attached to simple rails which require a minimum of anchor penetrations. Seismic tolerance The Trinamount III system itself is strong enough to meet seismic requirements. When properly attached to the building structure, the system is seismically safe. You should consult a qualified seismic structural engineer if you plan to install in a seismic area. Wind loading Trinamount III has been wind-tunnel tested to resist winds up to120 MPH, and each design is approved by a structural engineer. Snow & dust Trinamount III systems are fixed at 11 degrees, a tilt that has proven effective in minimizing buildup of dirt and debris and which promotes natural cleaning in a typical rainfall cycle. Repair & reuse; moving Trina PV panels can easily be removed and replaced, if necessary. Should you decide to move your array, all parts of the Trinamount III are re-usable. Use of TrinaSmart modules can save on diagnostics costs as well, as the system operator can more quickly identify system issues and make repairs fast, minimizes production loss. 8

9 Table 4: PV Panel Criteria Considerations Trina Solar Solutions Mfr s end-to-end product control Many PV panel vendors are merely assemblers of components made by others. This is not necessarily bad, but a company such as Trina Solar, which controls its production from silicon to finished panel, is better able to control quality and obtain the best possible panel performance, Mfr s sustainability & recycling Trina Solar has a panel recycling program with global reach. In addition, Trina operates an extremely green facility for panel production. Trina s accomplishments in this area are described in our Sustainable Development Report. You can obtain a copy from your Trina distributor or from Trina directly. Commitment to renewables targets Trina Solar is actively engaged with governments in setting and reaching targets for renewable energy, such as the UK s Microgeneration Certification Scheme. If your country has such a program, talk to Trina and see how we can help. Mfr s worldwide presence Trina has created a worldwide network of trained and qualified partners to assist you before and after the sale. We also operate a network of design centers so that you can get support 24/7. 9

10 Appendix C Glossary Alternating current (AC) Array Azimuth Balance of System (BOS) Base load Cell Solar Terminology the type of electric current that powers all electric appliances in your home a set of photovoltaic panels. A home solar electric system might include several arrays on different parts of the roof an important measurement (usually in degrees) used to optimize the placement of photovoltaic panels. The azimuth angle is the compass direction from which the sunlight is coming, and therefore where solar panels should optimally face for the most solar power production. A positive azimuth angle generally indicates the sun is east of south, and a negative azimuth angle generally indicates the sun is west of south. all the parts of a solar electric system excluding the solar panels and the inverter. Balance of system usually includes items like racking, wires, conduit, and safety shut-offs. The balance of system might account for 15% of the total cost of a solar electric system the amount of electric power a utility must supply constantly to meet the demand for energy the smallest part of a solar panel that converts light into solar electricity Direct current (DC) Gigawatt one billion watts Grid Grid tied/grid connected Ground mount Interconnection Inverter Kilowatt One thousand watts a type of low voltage electrical current. DC electricity is produced by solar cells and must be converted into AC before it s usable in a house a system of high tension cables in a region that distributes electricity to homes, businesses, and other buildings a solar system that is connected to the power grid and uses the grid as a backup source of power a solar electrical system that is mounted on the ground instead of on a roof the process of hooking up a solar electrical system to the power grid the electrical device that converts direct current (DC) electricity into alternating current (AC) electricity Kilowatt-hour (kwh) 1,000 thousand watts acting over a period of one hour. A kwh is the unit of energy Low-slope Roof typically, a commercial roof with ten degrees or less of roof pitch Megawatt Module Monocrystalline panel Multicrystalline panel Net meter Panel or Solar Panel one million watts a solar panel, or a group of solar cells a solar panel that s made from a large, single silicon crystal and has a patchwork pattern. Monocrystalline panels are more expensive and more efficient than multi- or polycrystalline panels. (also polycrystalline) a solar panel that s made from small silicon crystals oriented in lots of different directions. Multicrystalline panels are less expensive and less efficient than monocrystalline panels. an electricity meter that spins both forward and backwards. It can track how much electricity your solar system puts into the power grid and how much electricity your home pulls out of the grid. a group of solar cells; a module 10

11 Glossary Solar Terminology continued Peak demand (charges) Peak demand is the period of the day when the Utility is experiencing its highest volume of energy demand; in many markets, commercial users are charged higher rates during peak demand periods, and the resulting charge is a higher incremental cost-per-kilowatt-hour. Photon Photovoltaic a packet of light energy. the process of converting light into electricity. Polycrystalline panel (also multicrystalline) a solar panel that s made from small silicon crystals oriented in lots of different directions. Polycrystalline panels are less expensive and less efficient than monocrystalline panels. Power purchase agreement (PPA) = a contract between a power producer and a power consumer, which states that the consumer will purchase a certain amount of power from the producer. Power density Roof coverage ratio Roof pitch the ratio of watts per square foot that a solar power generator provides, often used as a measure of system efficiency or space efficiency. the percentage of unobstructed roof area that can be covered in solar panels as a percentage of the total roof area. the angle (above zero) a roof makes with the horizon, generally to allow for water run-off. Semiconductor a material that has a limited ability to conduct electric current. Semiconductors used in different types of solar panels include copper indium diselenide, cadmium telluride gallium arsenide, and silicon. Silicon Solar constant Solar energy Solar power Solar electricity a dark gray, semi-metallic, chemical element. Silicon is the material most commonly used semiconductor used in solar cells and computer chips. the average amount of solar radiation that reaches the earth s upper atmosphere, equal to 1353 watts per square meter. power that is generated by the sun. Solar noon the time of day when the sun reaches its highest point in the sky. This time divides the daylight hours for that day exactly in half. Solar noon may be quite a bit different from clock noon. Thin film panel a solar panel that is thin and flexible. The term refers to both amorphous photovoltaic solar panels, which use silicon as their semiconductor, and panels that use other semiconductors like cadmium telluride and copper indium gallium diselenide. Tilt the angle a solar panel makes with the horizon. The ideal tilt for a location will mean that the panels absorb as much sunlight as possible. Watt a unit of power equal to amps times volts. 11