Power Dev Power Dev, Nov. issue : 20

NOVEMBER 2011 ISSUE N°3 WHA T’S INSIDE Photovoltaic micro-inverter from Enphase Energy With more than thirty manufacturers of inverters in the world and a market declining, it is increasingly dif fi cult to differentiate its products from those of competition. E nphase Energy is following a different way by offering its third generation of micro-inverters, a technology pioneered by the California-based company. The M215 (215 watts) micro-inverter is used to convert direct current (DC) from individual solar panel to alternating current (AC). It is being touted as the most ef fi cient micro-inverter at 96% ef fi ciency. It consists in costing all the components of the system as well as the added value (assembly, tests,…) in order to obtain the production cost. Considering the quantities to be produced and the manufacturer data allows calculating the objective selling price. The studies begin with a careful dismantling of the system in order to identify and compile all its constitutive elements. Once the bill of material is established, each element is priced using either the component data base or speci fi c (integrated circuits, plastic and metal parts, displays …). This analysis gives the material cost of the system. The added value cost is worked out by modeling the speci fi c assembly fl ow of the system. If the system includes ASICs, the Reverse Costing method for integrated circuits is applied to price them. “The complete bill of material of the micro-inverter includes more than 400 electrical and mechanical components,” explains Wilfried Théron. Technology analysis Enphase M215 Micro-inverter. After the removing of the metallic covers of the (Courtesy of System Plus Consulting) Enphase Energy M215 micro-inverter, we have seen that it was completely fi lled with epoxy resin. The next step was to remove all this resin Bene fi ts of the micro-inverters: • Monitoring is done under each panel and by manually to avoid damaging the components and this way it is more precise and it minimizes the their markings. impact of a potential problems on a panel like The micro-inverter holds one electronic board leaves, shadow, … • Installation costs are cheaper than standard including an Application Speci fi c Integrated Circuit (ASIC), designed by Enphase Energy. The MCU (central or string) inverter for small installations • The current fl ow is low voltage, low and alternative is a member of the 8051 family. The main power semiconductors are MOSFET provided by ST current which provides more security • General maintenance costs seem lower because Microelectronics. it is easier to identify a faulty panel. Disadvantages of the micro-inverters: • The price in euro by watt is higher than the standard inverters • The manufacturability may be a widespread problem, as it involves huge quantities • The ef fi ciency of a micro-inverter is lower than that of a standard inverter. What is a Reverse Costing analysis? The reverse costing analysis is performed on electronic systems to calculate the production cost of an electronic material and/or to compare the technological solutions of similar products. Inside of the Enphase M215 Microinverter. (Courtesy of System Plus Consulting) 20 POWER Dev’

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