By Delta Energy Systems
Glenn Skutt, an electrical engineer with PowerHub Systems in the Town of Blacksburg, Virginia, the U.S.A., was contemplating solar power for his home and had already signed up for one of the state¡¯s solar incentive programs.
Meanwhile, in the spring of 2011, Delta Energy Systems had begun shipping its fourth-generation SOLIVIA solar inverters to the U.S.A. and was seeking homeowners who would allow the inverters to be installed for gathering test data. As it happens, Skutt was doing some consulting work with Delta at the time and volunteered to have the SOLIVIA inverters installed at his home, which comprises one side of a three-story duplex¦¡each floor with about 760 square feet of living space.
Because Skutt¡¯s is a three-story house, the Photovoltaic (PV) installation would entail both roof- and ground-mounted solar panels¦¡essentially two systems, with one inverter (the SOLIVIA 3.3) in each. The roof would have three strings of panels¦¡two strings with six panels and one string with four panels, the ground system nine panels, and the inverters would be mounted on the outside of the house.
To install the solar power system, Skutt engaged Solar Connexion, a regional renewable-energy contractor, which knew how critical a part the solar (or string) inverter plays in a PV system¦¡being its only active electronic component. The contractor had experience installing virtually every make and model of inverter available in the U.S.A. and was also familiar with the new SOLIVIA 3.3 and its:
-Dynamic MPPT (Maximum Power Point Tracking);
-Three-stage design, enabling a wide range of operating voltages (125V-540V) that makes it suitable for a broad variety of PV installations;
-Durable die-cast aluminum enclosure;
-NEMA 4 electronics protection rating, affirming that the watertight unit is suitable for the outdoor environment; and
-Smaller size, compared to most other high-frequency transformer-based inverters.
According to Skutt, the installation was quick and easy for the contractor. ¡°It was really a combination of features that simplified the job,¡± he says, such as:
-The wire box is cleanly laid and all the terminals easy to find (the AC and DC side terminals are separated, and there are clear labels in the box and in the manual);
-The unit has handles on the heat sink that make it easier to lift;
-The unit has a DC disconnect built in, which avoids unnecessary installation of an external DC disconnect;
-All wiring can be done from the wiring box, so there is no need for the installer to get inside the inverter stage to configure jumpers, unlike with some inverters;
-The installer can select the grounding configuration (either negative or positive) in the software and enable configuration by simply swapping two wires in the wiring box; and
-The mounting plate allows the wiring box to be left on the wall should the inverter ever need to removed for servicing.
¡°Some of these features are often missing in other inverters,¡± says Skutt. ¡°What really made the difference was how much attention to detail Delta puts into making its solar inverters so rugged and easy to connect up.¡±
The installation also included Delta¡¯s SOLIVIA Monitor system, comprising a gateway, a database, and a web application. Custom designed to work with the SOLIVIA solar inverters, it lets Skutt monitor both of his PV systems via the Internet¦¡providing him with real-time and historical data as well as alerting him to potential problems.
So far, Skutt has not experienced any problems with any part of his two PV systems. As for the SOLIVIA inverters, he particularly likes the elegant, compact design of the casing, the intuitive user interface, and the display¡¯s brightness and wide viewing angle.
Speaking as an electrical engineer, he adds, ¡°The inverter¡¯s three-stage design produces a relatively flat efficiency curve over the power range, and that¡¯s very good. I also like its wide input range, which makes the string design flexible and easy.¡±
Happy in his newly solar-powered home, Glenn Skutt reflects on what made it all happen when it did¦¡his consulting at Delta Energy Systems just as it was looking for volunteers to field-test its new SOLIVIA solar inverters. It was perfect timing¦¡and a perfect fit.
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